{"$schema":"nativecad-dfm-pack/1","id":"composites","title":"Composites: plies, carbon fibre, sandwich and how they are really made","sector":"composites","version":"2026-11-04","summary":"Ply properties for compositeLaminate with stated knockdowns, process chains and the CAD they demand, tooling and CTE, layup rules with numbers, bonded and bolted joints, sandwich checks, machining, NDT and coupon tests. Numbers tagged SRC or EST in basis.","aliases":["carbon fibre","cfrp","prepreg","laminate","sandwich","ply","plies","ply drop","layup","lay-up","honeycomb","ply book","drape","out of autoclave"],"crossSector":false,"size":"full","sources":[{"id":"ncamp-im7-8552","title":"NCAMP NCP-RP-2009-028 Rev B: Hexcel 8552 IM7 UD 190 gsm 35% RC statistical analysis (B-basis)","accessed":"2026-11-04","url":"https://wichita.edu/industry_and_defense/NIAR/Documents/NCP-RP-2009-028-Rev-B-HEXCEL-8552-IM7-Uni-SAR-4-16-2019.pdf"},{"id":"hexcel-8552-us","title":"Hexcel HexPly 8552 product data sheet (US, FTA-072-2-MY20)","accessed":"2026-11-04","url":"https://hexcel.com/wp-content/uploads/2026/01/HexPly_8552_us_DataSheet.pdf"},{"id":"hexcel-8552-eu","title":"Hexcel HexPly 8552 product data sheet (EU, 2023)","accessed":"2026-11-04","url":"https://hexcel.com/wp-content/uploads/2025/12/HexPly_8552_eu_DataSheet1.pdf"},{"id":"hexcel-m56","title":"Hexcel HexPly M56 out-of-autoclave data sheet","accessed":"2026-11-04","url":"https://hexcel.com/wp-content/uploads/2026/01/HexPly_M56_global_DataSheet.pdf"},{"id":"hexcel-as4","title":"Hexcel HexTow AS4 fibre data sheet (with 8552 composite properties at 60% Vf)","accessed":"2026-11-04","url":"https://www.rockwestcomposites.com/media/wysiwyg/AS4.pdf"},{"id":"toray-manual","title":"Toray CMA Torayca technical manual, rev 4/2020 (fibre property table)","accessed":"2026-11-04","url":"https://www.toraycma.com/wp-content/uploads/Torayca-Technical-Manual_4-28-2020.pdf"},{"id":"toray-t700s","title":"Toray T700S data sheet (composite properties normalised to 60% Vf)","accessed":"2026-11-04","url":"https://www.toraycma.com/wp-content/uploads/T700S-Data-Sheet.pdf"},{"id":"toray-t800s","title":"Toray T800S data sheet (composite properties normalised to 60% Vf)","accessed":"2026-11-04","url":"https://www.toraycma.com/wp-content/uploads/T800S-Data-Sheet.pdf"},{"id":"toray-m55j","title":"Toray M55J data sheet CFA-017 (250F and 350F epoxy, 60% Vf)","accessed":"2026-11-04","url":"https://sfccdev.rockwestcomposites.com/on/demandware.static/-/Sites-rwc-master-catalog/default/dw9371cfa8/downloads/M55J.pdf"},{"id":"toray-tc1200","title":"Toray Cetex TC1200 PEEK data sheet v4.0, 2024","accessed":"2026-11-04","url":"https://toraytac-staging.azurewebsites.net/media/7765d981-1f9f-472d-bf24-69a647412e38/oMCfAQ/TAC/Documents/Data_sheets/Thermoplastic/UD%20tapes,%20prepregs%20and%20laminates/Toray-Cetex-TC1200_PEEK_PDS.pdf"},{"id":"cw-paek","title":"CompositesWorld: PEEK vs PEKK vs PAEK and continuous compression molding","accessed":"2026-11-04","url":"https://www.compositesworld.com/blog/post/peek-vs-pekk-vs-paek-and-continuous-compression-molding"},{"id":"hexcel-hsd","title":"Hexcel HexWeb Honeycomb Sandwich Design Technology, AGU 075b (2000)","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/Honeycomb_Sandwich_Design_Technology.pdf"},{"id":"hexcel-prepreg","title":"Hexcel HexPly Prepreg Technology manual","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/Prepreg_Technology-1.pdf"},{"id":"hexcel-lcm","title":"Hexcel Liquid Composite Moulding Technology manual","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/LiquidCompositeMouldingT.pdf"},{"id":"hexcel-rtm6","title":"Hexcel HexFlow RTM6/RTM6-2 safety and processing guidelines","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/HexFlowRTM6RTM62Guidelines.pdf"},{"id":"hexcel-hextool","title":"Hexcel HexTool user guide (M61, M81 machinable tooling)","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/HexTool_UserGuide.pdf"},{"id":"hexcel-toolfab","title":"Hexcel HexTOOL tooling fabrics user guide","accessed":"2026-11-04","url":"https://hexcel.com/wp-content/uploads/2026/01/HexTOOL_Fabrics_UserGuide.pdf"},{"id":"hexcel-hexmc","title":"Hexcel HexMC user guide (compression moulding compound)","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/HexMCUserGuide.pdf"},{"id":"hexcel-repair","title":"Hexcel Composite Repair guide, UTC 102 (1999)","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/Composite_Repair.pdf"},{"id":"hexcel-bonding","title":"Hexcel HexBond Adhesive Bonding Technology manual","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/Adhesive_Bonding_Technology.pdf"},{"id":"hexcel-sandwich-test","title":"Hexcel Mechanical Testing of Sandwich Panels technical notes","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/SandwichPanels_global.pdf"},{"id":"hexcel-hrh10","title":"Hexcel HexWeb HRH-10 aramid honeycomb data sheet","accessed":"2026-11-04","url":"https://hexcel.com/wp-content/uploads/2026/01/HexWeb_HRH10_DataSheet_us.pdf"},{"id":"hexcel-attrib","title":"Hexcel HexWeb Honeycomb Attributes and Properties","accessed":"2026-11-04","url":"https://www.hexcel.com/wp-content/uploads/2026/01/HexWebHoneycombAttributesandProperties.pdf"},{"id":"evonik-rist","title":"Evonik ROHACELL RIST/RIST-HT product information (2026)","accessed":"2026-11-04","url":"https://products.evonik.com/assets/33/86/ROHACELL_RIST_HT_2026_03_16_EN_243386.pdf"},{"id":"diab-h","title":"Diab Divinycell H technical data, rev 19 (2020)","accessed":"2026-11-04","url":"https://www.boatbuildercentral.com/MSDS/Diab-Divinycell-H-June-2020-rev19-SI.pdf"},{"id":"nasa-pd-ed-1217","title":"NASA Preferred Reliability Practice PD-ED-1217: structural laminate composites for space","accessed":"2026-11-04","url":"https://extapps.ksc.nasa.gov/Reliability/Documents/Preferred_Practices/1217.pdf"},{"id":"cw-tooling","title":"CompositesWorld: Tooling (2015 survey)","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/tooling-2015","note":"supplier claims in part"},{"id":"cw-cai","title":"CompositesWorld (Adams): damage tolerance testing of composites","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/damage-tolerance-testing-of-composites%282%29"},{"id":"cw-tension","title":"CompositesWorld (Adams): tensile testing composites","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/tensile-testing-of-composites-simple-in-concept-difficult-in-practice"},{"id":"cw-textile","title":"CompositesWorld (Adams): mechanical testing of textile composites","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/mechanical-testing-of-textile-composites"},{"id":"cw-compression","title":"CompositesWorld (Adams): optimum UD compression testing","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/optimum-unidirectional-compression-testing-of-composites"},{"id":"cw-shear","title":"CompositesWorld (Adams): standardized composites shear test methods","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/from-laminas-to-laminates-standardized-test-methods-for-composites-shear-testing"},{"id":"cw-bolted","title":"CompositesWorld (Adams): testing to support composite bolted joint analysis","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/testing-to-support-composite-bolted-joint-analysis"},{"id":"cw-fracture","title":"CompositesWorld (Adams): mixed-mode fracture toughness of composites","accessed":"2026-11-04","url":"https://www.compositesworld.com/articles/mixed-mode-fracture-toughness-of-composites"},{"id":"abbott-inserts","title":"Abbott Aerospace AA-SB-001 12.2.6: potted inserts (from ECSS-E-HB-32-22A)","accessed":"2026-11-04","url":"https://www.abbottaerospace.com/?p=55945"},{"id":"dlr-laminate","title":"DLR IB-2025-144 master thesis (Ramesh): laminate design guidelines review","accessed":"2026-11-04","url":"https://elib.dlr.de/216954/1/IB_2025_144_MA_Ramesh_Geschw%C3%A4rzt.pdf"},{"id":"obata-2021","title":"Obata et al., Composite Structures: tapered FRP laminate with ply drop-off","accessed":"2026-11-04","url":"https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/86564/1/Compos%20Struct_Obata_final.pdf"},{"id":"osmeda-2012","title":"Osmeda, Institute of Aviation (READ 2012): process-induced distortion in a composite spar","accessed":"2026-11-04","url":"https://read.meil.pw.edu.pl/wp-content/uploads/Program/2012/Papers/Students/Paper_READ2012_Osmeda_Anna.pdf"},{"id":"afp-limits","title":"Huddersfield/White Rose: limitations of processing CFRP using automated fibre placement","accessed":"2026-11-04","url":"https://eprints.whiterose.ac.uk/104178/7/Limitations.pdf"},{"id":"strongwell-tol","title":"Strongwell design manual section 5: pultruded tolerances after ASTM D3917","accessed":"2026-11-04","url":"https://www.strongwell.com/wp-content/uploads/2024/11/Section05m-1124.pdf"},{"id":"wiki-invar","title":"Wikipedia: Invar","accessed":"2026-11-04","url":"https://en.wikipedia.org/wiki/Invar"},{"id":"wiki-cte","title":"Wikipedia: Thermal expansion (table of CTE at 20 C)","accessed":"2026-11-04","url":"https://en.wikipedia.org/wiki/Thermal_expansion"},{"id":"xc110","title":"Easy Composites XPREG XC110 processing guide (OOA prepreg, shop level)","accessed":"2026-11-04","url":"https://media.easycomposites.eu/datasheets/XPREG%20XC110%20Complete%20Processing%20Guide.pdf"},{"id":"eng-tips-bolted","title":"Eng-Tips forum thread: fasteners in composite materials (search excerpt, not opened)","accessed":"2026-11-04","url":"https://www.eng-tips.com/threads/fasteners-in-composite-materials.443563/post-8382736","note":"practitioner figures; the page refused a direct fetch"},{"id":"nas1-19347","title":"Bailie, Ley, Pasricha: Composite Laminate Design Guidelines, NASA contract NAS1-19347 Task 22, 1997","accessed":"2026-11-04","note":"guideline text seen only in a search excerpt; full report not opened"},{"id":"hart-smith-cr112237","title":"Hart-Smith, NASA CR-112237: adhesive-bonded scarf and stepped-lap joints (1973)","accessed":"2026-11-04","url":"https://ntrs.nasa.gov/api/citations/19740005084/downloads/19740005084.pdf"},{"id":"astm-composites","title":"ASTM committee D30 composite test methods (paywalled; names and scope only)","accessed":"2026-11-04","url":"https://www.astm.org/Standards/composite-standards.html"}],"entries":[{"id":"allowable-knockdowns","kind":"rule","tier":1,"title":"What each strain allowable in this pack assumes","summary":"Rows name their condition. RTD mean: no knockdown, never a design value. ETW B: 250 F wet, B-basis. design-OH: 0.0053 tension, 0.0043 compression, from open-hole QI B-basis (tension CTD, compression ETW), which covers holes and hot/wet but is not a CAI check.","applies":[],"value":{"table":[{"condition":"RTD-mean","covers":"room temperature dry, mean","use":"comparison, sanity only"},{"condition":"ETW-B","covers":"250 F wet, lamina B-basis","use":"matrix-mode hot/wet check"},{"condition":"design-OH","covers":"open hole, hot/wet, QI B-basis","use":"first-pass laminate sizing"},{"condition":"EST-*","covers":"transferred, see row and entry basis","use":"until a test or a supplier value replaces it"}]},"basis":"SRC: NCAMP QI OHT CTD B 44.35 ksi / 8.35 Msi = 0.0053; OHC ETW mod-CV B 30.86 ksi / 7.13 Msi = 0.0043. Tension value is the B-value; compression is modified-CV B. The strains are EST divisions of those two published values.","sources":["ncamp-im7-8552"],"tags":["hot-wet","damage-tolerance"]},{"id":"first-pass-allowable-choice","kind":"rule","tier":1,"title":"Which allowable to use for a first-pass laminate","summary":"Size a first pass on open-hole fibre strain: 0.0053 tension (CTD), 0.0043 compression (ETW), QI IM7/8552, at 1.5 factor of safety and 2.0 around fasteners. Use RTD mean only to compare materials. Then run matrix, buckling and CAI checks separately.","applies":[],"value":{"table":[{"mode":"tension","strain":0.0053},{"mode":"compression","strain":0.0043},{"factor":"general","value":1.5},{"factor":"around fasteners","value":2}]},"basis":"SRC: NCAMP QI open-hole B-basis strength / QI modulus (OHT CTD, OHC ETW); factors 1.5 and 2.0 from NASA PD-ED-1217. EST: other carbon/epoxy systems.","sources":["ncamp-im7-8552","nasa-pd-ed-1217"],"tags":["margin"],"see":["composites/first-vs-last-ply"]},{"id":"mat-im7-8552-ud","kind":"material","tier":1,"title":"IM7/8552 UD tape: intermediate-modulus ply (NCAMP)","summary":"IM7/8552 190 gsm 35% RC: E1 158.5 GPa, E2 9.0, G12 4.7, nu12 0.316, 0.183 mm ply. Strain to failure RTD mean 0.0158 t, 0.0124 c; ETW B 0.0110 t, 0.0071 c. Tg 406 F dry, 321 F wet (DMA).","applies":["primary structure","wing skin","monocoque"],"value":{"table":[{"id":"im7-8552-rtd-mean","kind":"ud","condition":"RTD-mean","E1":158511,"E2":8963,"G12":4688,"nu12":0.316,"tMm":0.183,"rho":1.57,"e1t":0.0158,"e1c":0.0124,"e2t":0.00715,"e2c":0.0294,"g12":0.0194},{"id":"im7-8552-etw-b","kind":"ud","condition":"ETW-B","E1":165474,"E2":5585,"G12":2137,"nu12":0.393,"tMm":0.183,"rho":1.57,"e1t":0.011,"e1c":0.00709,"e2t":0.0037,"e2c":0.0141,"g12":0.0145},{"id":"im7-8552-design-oh","kind":"ud","condition":"design-OH","E1":158511,"E2":8963,"G12":4688,"nu12":0.316,"tMm":0.183,"rho":1.57,"e1t":0.0053,"e1c":0.0043,"e2t":0.0037,"e2c":0.0141,"g12":0.0145}]},"basis":"SRC: NCAMP Table 3-3, normalised to 0.0072 in ply; ksi and Msi converted. Strains are strength / modulus (EST arithmetic). rho from Hexcel 8552/35%/IM7 at 134 gsm: EST same at 190 gsm.","sources":["ncamp-im7-8552","hexcel-8552-eu"],"tags":["b-basis"]},{"id":"mat-as4-8552-ud","kind":"material","tier":2,"title":"AS4/8552 UD tape: standard-modulus ply","summary":"AS4/8552 134 gsm at 60% Vf: E1 141 GPa, nu12 0.302, 0.130 mm ply, 1.58 g/cm3. RTD tension 2205 MPa, 1.55% strain; compression 1530 MPa. On the hot/wet row 0 deg compression falls to 184 ksi (row labelled 195 F; footnote markers reach 250 F).","applies":[],"value":{"table":[{"id":"as4-8552-rtd-mean","kind":"ud","condition":"RTD-mean","E1":141000,"E2":9584,"G12":4688,"nu12":0.302,"tMm":0.13,"rho":1.58,"e1t":0.0155,"e1c":0.012,"e2t":0.00845,"e2c":0.0272,"g12":0.0244},{"id":"as4-8552-hot-wet","kind":"ud","condition":"EST-hot-wet","E1":141000,"E2":5972,"G12":2137,"nu12":0.302,"tMm":0.13,"rho":1.58,"e1t":0.0155,"e1c":0.0102,"e2t":0.0037,"e2c":0.0169,"g12":0.0121},{"id":"as4-8552-design-oh","kind":"ud","condition":"EST-design-OH","E1":141000,"E2":9584,"G12":4688,"nu12":0.302,"tMm":0.13,"rho":1.58,"e1t":0.0053,"e1c":0.0043,"e2t":0.0037,"e2c":0.0141,"g12":0.0145}]},"basis":"SRC: HexTow AS4 and HexPly 8552 tables. EST: G12 taken from NCAMP IM7/8552 (same resin), so g12 is estimated; design row transfers NCAMP QI strains; wet row E2-side terms scale by IM7 ratio.","sources":["hexcel-as4","hexcel-8552-us","hexcel-8552-eu"],"tags":["ud","standard-modulus","as4","8552"]},{"id":"mat-twill-2x2-sm","kind":"material","tier":1,"title":"Standard-modulus 2x2 twill prepreg, AS4C 6K / M56 OOA","summary":"2x2 twill AS4C-6K 285 gsm, M56 oven cure, 50.3% Vf as cured: E 67 GPa, G12 3.7, 0.316 mm ply, 1.50 g/cm3. RTD tension 787, compression 807 MPa (normalised to 56% Vf), shear 99 MPa. Strain 0.0117 t, 0.0139 c mean.","applies":["skin","cosmetic ply","bodywork","outer ply"],"value":{"table":[{"id":"twill-2x2-rtd-mean","kind":"fabric","condition":"RTD-mean","E1":67000,"E2":67000,"G12":3700,"nu12":0.05,"tMm":0.316,"rho":1.5,"e1t":0.0117,"e1c":0.0139,"e2t":0.0117,"e2c":0.0139,"g12":0.0268},{"id":"twill-2x2-design-oh","kind":"fabric","condition":"EST-design-OH","E1":67000,"E2":67000,"G12":3700,"nu12":0.05,"tMm":0.316,"rho":1.5,"e1t":0.0053,"e1c":0.0043,"e2t":0.0053,"e2c":0.0043,"g12":0.0145}]},"basis":"SRC: HexPly M56 sheet, EN test methods. EST: E2 = E1 (balanced fabric); nu12 0.05 from the Hexcel woven carbon row; design row transfers NCAMP QI strains from a tape system.","sources":["hexcel-m56","hexcel-hsd","ncamp-im7-8552"],"tags":["fabric"]},{"id":"mat-as4-8552-pw","kind":"material","tier":3,"title":"AS4 3K plain weave AGP193-PW / 8552","summary":"AGP193-PW 8552, 37% RC: E 67.6 GPa warp, 65.5 fill, 0.195 mm ply, 1.57 g/cm3, 55% Vf. 120 ksi tension, 128 ksi compression at 77 F dry; 85 ksi compression on the hot/wet row (195 F label).","applies":[],"value":{"table":[{"id":"as4-pw-rtd-mean","kind":"fabric","condition":"RTD-mean","E1":67569,"E2":65500,"G12":3500,"nu12":0.05,"tMm":0.195,"rho":1.57,"e1t":0.0122,"e1c":0.0147,"e2t":0.0121,"e2c":0.0141,"g12":0.0366},{"id":"as4-pw-hot-wet","kind":"fabric","condition":"EST-hot-wet","E1":67569,"E2":65500,"G12":2500,"nu12":0.05,"tMm":0.195,"rho":1.57,"e1t":0.0122,"e1c":0.00977,"e2t":0.0121,"e2c":0.00978,"g12":0.0145}]},"basis":"SRC: HexPly 8552 sheets (US table in ksi and Msi). EST: nu12 from Hexcel woven row; G12 3.5 GPa and shear strength 128 MPa from M56 on the same fabric; wet row keeps dry moduli.","sources":["hexcel-8552-us","hexcel-8552-eu","hexcel-m56","hexcel-hsd"],"tags":["fabric","plain-weave","as4"]},{"id":"mat-t700s-ud","kind":"material","tier":3,"title":"T700S UD on epoxy, Toray composite values","summary":"T700S 60% Vf: E1 134 GPa, 2860 MPa tension, 1450 MPa compression, 81 MPa at 90 deg. Fibre 4900 MPa, 230 GPa, 1.80 g/cm3. Toray gives no E2, G12 or ply thickness here, so those are estimates.","applies":[],"value":{"table":[{"id":"t700s-est-rtd","kind":"ud","condition":"EST-RTD-typical","E1":134000,"E2":8963,"G12":4688,"nu12":0.3,"tMm":0.125,"rho":1.58,"e1t":0.0213,"e1c":0.0124,"e2t":0.00904,"e2c":0.0294,"g12":0.0194},{"id":"t700s-est-design-oh","kind":"ud","condition":"EST-design-OH","E1":134000,"E2":8963,"G12":4688,"nu12":0.3,"tMm":0.125,"rho":1.58,"e1t":0.0053,"e1c":0.0043,"e2t":0.0037,"e2c":0.0141,"g12":0.0145}]},"basis":"SRC: Toray T700S strength and E1. EST: E2, G12, e2c, g12 from NCAMP IM7/8552; nu12 0.3; tMm 0.125 from Hexcel UD row; rho by rule of mixtures; compression modulus 0.87 E1 from the IM7 ratio.","sources":["toray-t700s","toray-manual","ncamp-im7-8552","hexcel-hsd"],"tags":["ud","standard-modulus","t700","industrial"]},{"id":"mat-t800s-ud","kind":"material","tier":2,"title":"T800S UD on epoxy: intermediate modulus","summary":"T800S 60% Vf: E1 163 GPa, 3290 MPa tension, 1490 MPa compression, 135 MPa in-plane shear, 79 MPa at 90 deg, ILSS 87.9 MPa. Fibre 5880 MPa, 294 GPa, CTE -0.4 x 10^-6/C.","applies":[],"value":{"table":[{"id":"t800s-est-rtd","kind":"ud","condition":"EST-RTD-typical","E1":163000,"E2":8963,"G12":4688,"nu12":0.3,"tMm":0.125,"rho":1.58,"e1t":0.0202,"e1c":0.0105,"e2t":0.00881,"e2c":0.0294,"g12":0.0194},{"id":"t800s-est-design-oh","kind":"ud","condition":"EST-design-OH","E1":163000,"E2":8963,"G12":4688,"nu12":0.3,"tMm":0.125,"rho":1.58,"e1t":0.0053,"e1c":0.0043,"e2t":0.0037,"e2c":0.0141,"g12":0.0145}]},"basis":"SRC: Toray T800S sheet. EST: E2, G12, e2c from NCAMP IM7/8552; nu12 0.3; tMm 0.125; rho by rule of mixtures; compression modulus 0.87 E1; g12 capped at the NCAMP RTD value.","sources":["toray-t800s","ncamp-im7-8552","hexcel-hsd"],"tags":["ud","intermediate-modulus","t800"]},{"id":"mat-m55j-ud","kind":"material","tier":2,"title":"M55J UD on epoxy: high-modulus, low-strain ply","summary":"M55J on 350 F epoxy, 60% Vf: E1 300 GPa, 1860 MPa tension, 0.6% strain, 835 MPa compression, 285 GPa compressive, 35 MPa at 90 deg. Compression strain is only 0.0029: a stiffness ply, not a strength ply.","applies":["stiffness-critical","optical bench","wing"],"value":{"table":[{"id":"m55j-est-rtd","kind":"ud","condition":"EST-RTD-typical","E1":300000,"E2":6000,"G12":4000,"nu12":0.3,"tMm":0.1,"rho":1.65,"e1t":0.006,"e1c":0.00293,"e2t":0.00583,"e2c":0.02,"g12":0.011}]},"basis":"SRC: Toray M55J sheet strengths and E1. EST: E2 6 GPa, G12 4 GPa, nu12 0.3, tMm 0.10, e2c 0.02 by judgement with no opened source; rho by rule of mixtures. Replace before relying on matrix-mode margins.","sources":["toray-m55j"],"tags":["ud","high-modulus","m55j"]},{"id":"fibre-grades","kind":"material","tier":2,"title":"Carbon fibre grades: strand strength and modulus","summary":"Strand values: T300 3530 MPa/230 GPa; AS4 4433/231; T700S 4900/230; T800S 5880/294; T1100 7000/324; M40J 4400/377; M55J 4020/540; M60J 3820/588. Laminate E1 at 60% Vf is about 0.6 of fibre modulus. FIA F1 C15.2 limits: motorsport lane.","applies":[],"value":{"table":[{"fibre":"T300","MPa":3530,"GPa":230,"strainPct":1.5,"gcc":1.76},{"fibre":"AS4","MPa":4433,"GPa":231,"strainPct":1.8,"gcc":1.79},{"fibre":"T700S","MPa":4900,"GPa":230,"strainPct":2.1,"gcc":1.8},{"fibre":"T800H","MPa":5490,"GPa":294,"strainPct":1.9,"gcc":1.81},{"fibre":"T800S","MPa":5880,"GPa":294,"strainPct":2,"gcc":1.8},{"fibre":"T1100S","MPa":7000,"GPa":324,"strainPct":2,"gcc":1.79},{"fibre":"M40J","MPa":4400,"GPa":377,"strainPct":1.2,"gcc":1.77},{"fibre":"M46J","MPa":4200,"GPa":436,"strainPct":1,"gcc":1.84},{"fibre":"M55J","MPa":4020,"GPa":540,"strainPct":0.8,"gcc":1.91},{"fibre":"M60J","MPa":3820,"GPa":588,"strainPct":0.7,"gcc":1.93}]},"basis":"SRC: Toray manual rev 4/2020 and HexTow AS4 sheet, impregnated-strand tests for selection only. EST: the 0.6 factor (T800S 163/294 = 0.55; AS4 141/231 = 0.61).","sources":["toray-manual","hexcel-as4"],"tags":["fibre","grade","selection","f1"],"see":["materials/composite-cf-epoxy"]},{"id":"mat-peek-carbon-ud","kind":"material","tier":2,"title":"Carbon/PEEK UD tape TC1200: thermoplastic ply","summary":"TC1200 standard-modulus UD, 145 gsm, 34% RC: E1 135 GPa, E2 10, G12 5.2, 0.14 mm ply, 1.59 g/cm3. Tension 2410 MPa, compression 1300 MPa, 1210 MPa ETW. Tg 143 C, Tm 343 C. Indefinite ambient shelf life.","applies":[],"value":{"table":[{"id":"peek-carbon-rtd","kind":"ud","condition":"RTD-typical","E1":135000,"E2":10000,"G12":5200,"nu12":0.3,"tMm":0.14,"rho":1.59,"e1t":0.0179,"e1c":0.0105,"e2t":0.0086,"e2c":0.02,"g12":0.0292},{"id":"peek-carbon-etw","kind":"ud","condition":"EST-ETW-compression-only","E1":135000,"E2":10000,"G12":5200,"nu12":0.3,"tMm":0.14,"rho":1.59,"e1t":0.0179,"e1c":0.01,"e2t":0.0086,"e2c":0.02,"g12":0.0292}]},"basis":"SRC: Toray TC1200 data sheet v4.0, strains from strength / modulus. EST: nu12 0.3, e2c 0.02; e1t by strength over tensile modulus without a published failure strain.","sources":["toray-tc1200"],"tags":["thermoplastic","peek","ud","tape"]},{"id":"mat-glass-aramid-woven","kind":"material","tier":2,"title":"Woven glass and aramid facing plies on epoxy","summary":"7781-8HS glass: E 20/17 GPa t/c, 600/550 MPa, 0.25 mm, 0.47 kg/m2. 285K-4HS aramid: E 30/31 GPa, 500/150 MPa, 0.20 mm, 0.27 kg/m2. Aramid compression strain is only 0.0048: never a compression face.","applies":[],"value":{"table":[{"id":"glass-7781-rtd","kind":"fabric","condition":"RTD-typical","E1":20000,"E2":20000,"G12":3500,"nu12":0.13,"tMm":0.25,"rho":1.88,"e1t":0.03,"e1c":0.0324,"e2t":0.03,"e2c":0.0324,"g12":0.03},{"id":"aramid-285k-rtd","kind":"fabric","condition":"RTD-typical","E1":30000,"E2":30000,"G12":2000,"nu12":0.2,"tMm":0.2,"rho":1.35,"e1t":0.0167,"e1c":0.00484,"e2t":0.0167,"e2c":0.00484,"g12":0.02}]},"basis":"SRC: Hexcel AGU 075b Appendix II typical values. EST: G12 (3.5 GPa glass, 2 GPa aramid), g12 and rho (mass / thickness); the table gives one modulus per weave, so E2 = E1.","sources":["hexcel-hsd"],"tags":["fabric","glass","aramid","facing"],"see":["marine/material-grp-vinylester"]},{"id":"mat-film-adhesive","kind":"material","tier":2,"title":"Film adhesive as a thickness-and-mass ply","summary":"Structural film adhesive: 150-400 g/m2 for skin-to-core, 60-150 g/m2 where weight is critical. A 300 g/m2 film adds about 0.25 mm before flow. Models as a core-kind ply: mass and thickness only, no stiffness.","applies":[],"value":{"table":[{"id":"film-adhesive-300gsm","kind":"core","condition":"EST-uncured-thickness","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":0.25,"rho":1.2,"arealGm2":300}]},"basis":"SRC: areal mass ranges from Hexcel bonding manual. EST: rho 1.2 g/cm3 and the resulting 0.25 mm are typical epoxy-film arithmetic; no opened sheet states them.","sources":["hexcel-bonding"],"tags":["adhesive","film","bondline"]},{"id":"mat-honeycomb-aramid","kind":"material","tier":2,"title":"Aramid honeycomb HRH-10 1/8-3.0 (Nomex)","summary":"HRH-10 1/8 in 48 kg/m3: stabilised compression 2.4 MPa, Ec 138 MPa; L shear 1.25 MPa, GL 40; W shear 0.73 MPa, GW 25. Thickness tolerance 0.006 in up to 2 in. Density +/-10%. CTE 19.4 x 10^-6 in/in/F.","applies":["sandwich","floor panel","fairing","radome"],"value":{"table":[{"id":"hrh10-48","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.048,"Ec":138,"Fc":2.4,"GL":40,"FsL":1.25,"GW":25,"FsW":0.73,"cellMm":3.2},{"id":"hrh10-29","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.029,"Ec":60,"Fc":0.9,"GL":25,"FsL":0.5,"GW":17,"FsW":0.35,"cellMm":3.2},{"id":"hrh10-96","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.096,"Ec":400,"Fc":7.7,"GL":85,"FsL":2.6,"GW":50,"FsW":1.5,"cellMm":3.2}]},"basis":"SRC: Hexcel AGU 075b Appendix I typical RT values; tolerance from HRH-10 sheet; CTE from Attributes and Properties. Tested at 0.5 in core. tMm 10 is a placeholder: set your own core thickness.","sources":["hexcel-hsd","hexcel-hrh10","hexcel-attrib"],"tags":["core","honeycomb","aramid","nomex"]},{"id":"mat-honeycomb-aluminium","kind":"material","tier":2,"title":"Aluminium honeycomb 5052: stiffer, galvanically active","summary":"5052 3/16 in 50 kg/m3: compression 2.3 MPa, Ec 517; L 1.45 MPa, GL 310; W 0.9 MPa, GW 152. 72 kg/m3 1/8 in: 4.2 MPa, L 2.3. Isolate from carbon faces. Crushes uniformly, so it also serves as an energy absorber.","applies":[],"value":{"table":[{"id":"al5052-50","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.05,"Ec":517,"Fc":2.3,"GL":310,"FsL":1.45,"GW":152,"FsW":0.9,"cellMm":4.8},{"id":"al5052-72","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.072,"Ec":1034,"Fc":4.2,"GL":483,"FsL":2.3,"GW":214,"FsW":1.5,"cellMm":3.2}]},"basis":"SRC: Hexcel AGU 075b Appendix I typical RT values. EST: isolation from carbon is general galvanic practice (the opened Hexcel text covers corrosion coatings, not this pairing).","sources":["hexcel-hsd","hexcel-attrib"],"tags":["core","honeycomb","aluminium","crush"]},{"id":"mat-foam-pmi","kind":"material","tier":2,"title":"PMI foam ROHACELL RIST: heat-formable, cures with the skins","summary":"ROHACELL 71 RIST 75 kg/m3: compression 1.7 (min 1.1) MPa, shear 1.3 (1.0), G 42 (24). 110 RIST: 3.6 MPa, 2.4, G 70. RIST-HT runs infusion or RTM up to 180 C and 0.7 MPa. Thermoformable or CNC to shape.","applies":["rtm core","infusion core","wing rib"],"value":{"table":[{"id":"pmi-51","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.052,"Fc":0.8,"Et":75,"G":24,"Fs":0.8},{"id":"pmi-71","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.075,"Fc":1.7,"Et":105,"G":42,"Fs":1.3},{"id":"pmi-110","kind":"core","condition":"RT-typical","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.11,"Fc":3.6,"Et":180,"G":70,"Fs":2.4}]},"basis":"SRC: Evonik RIST/RIST-HT sheet (typical, minimum in brackets). tMm 10 is a placeholder. EST: Ec is not on this sheet, so the row carries the tensile modulus as Et rather than inventing an Ec.","sources":["evonik-rist"],"tags":["core","foam","pmi","rohacell"]},{"id":"mat-foam-pvc","kind":"material","tier":2,"title":"PVC foam Divinycell H: low-temperature cores","summary":"H100 100 kg/m3: compression 2.0 (min 1.65) MPa, Ec 135 (115); shear 1.6 (1.4), G 35 (28), shear strain 40%. H80: 1.4 MPa, 1.15, G 27. Continuous service to +70 C: not for a 180 C cure. Design from the minimum column.","applies":["marine","low-temperature cure","infusion"],"value":{"table":[{"id":"pvc-h80","kind":"core","condition":"RT-nominal","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.08,"Ec":90,"Fc":1.4,"G":27,"Fs":1.15},{"id":"pvc-h100","kind":"core","condition":"RT-nominal","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.1,"Ec":135,"Fc":2,"G":35,"Fs":1.6},{"id":"pvc-h100-min","kind":"core","condition":"RT-minimum","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.1,"Ec":115,"Fc":1.65,"G":28,"Fs":1.4},{"id":"pvc-h130","kind":"core","condition":"RT-nominal","E1":0,"E2":0,"G12":0,"nu12":0,"tMm":10,"rho":0.13,"Ec":170,"Fc":3,"G":40,"Fs":2.2}]},"basis":"SRC: Diab Divinycell H rev 19, at +23 C, perpendicular to plane. EST: reading the 180 C exclusion from the process-temperature row. tMm 10 is a placeholder.","sources":["diab-h"],"tags":["core","foam","pvc","divinycell"],"see":["marine/material-grp-vinylester"]},{"id":"process-autoclave-prepreg","kind":"process","tier":1,"title":"Hand layup prepreg plus autoclave: the reference chain","summary":"Cut, kit, lay up on the tool, debulk, bag, cure, trim, NDT. Autoclave runs 1-10 bar: one tool face gives a controlled surface and the bag face does not, so hold datums and tolerances on the tool side. Holds thick sections and complex shapes.","applies":["monocoque","wing","primary structure"],"value":{"table":[{"pressureBar":"1-10"}]},"basis":"SRC: Hexcel Prepreg Technology, pressure range and process. EST: the datum consequence is standard practice inferred from a one-sided tool.","sources":["hexcel-prepreg"],"tags":["autoclave"]},{"id":"autoclave-cad-consequences","kind":"note","tier":3,"title":"Autoclave part: what the CAD must carry","summary":"Model the tool surface as the OML, add net trim plus a stock band all round for bag sealing and test tags, avoid inside corners a bag bridges, and treat the bag-side thickness tolerance as much looser than the tool side. Tag ends double as acceptance coupons.","applies":[],"basis":"SRC: bag stack and tag-end coupons, Hexcel prepreg manual and NASA PD-ED-1217. EST: the CAD translation of them.","sources":["hexcel-prepreg","nasa-pd-ed-1217"],"tags":["autoclave","trim","bag","tag-end"]},{"id":"cure-cycle-8552","kind":"process","tier":1,"title":"Autoclave cure envelope, HexPly 8552 (typical 180 C system)","summary":"8552: full vacuum plus 15 psig; 3-5 F/min to 225 F; hold 30-60 min; raise to 85-100 psig, venting vacuum at 30 psig; 350 F for 120 +/-10 min; cool at 2-5 F/min to 150 F. Thick sections heat slower and need more dwell.","applies":["autoclave","cure"],"value":{"table":[{"step":"ramp","rate":"3-5 F/min","to":"225 F"},{"step":"dwell","time":"30-60 min","at":"225 F"},{"step":"pressure","value":"85-100 psig","ventVacuumAt":"30 psig"},{"step":"cure","time":"120 +/-10 min","at":"350 F"},{"step":"cool","rate":"2-5 F/min","to":"150 F"}]},"basis":"SRC: HexPly 8552 US data sheet cure procedure; the prepreg manual gives the slow-heat advice for large or thick parts. Printed in F and psig, so kept that way.","sources":["hexcel-8552-us","hexcel-prepreg"],"tags":["ramp","dwell","pressure"]},{"id":"prepreg-storage-life","kind":"rule","tier":2,"title":"Prepreg out-life, tack life and freezer life set the kit size","summary":"HexPly 8552: tack 10 days and out-life 30 days at 23 C, 12 months at -18 C sealed. Out-life accumulates from every freezer removal. Warm the sealed bag to room temperature before opening. A part longer to lay up than this must be split.","applies":[],"value":{"table":[{"life":"tack","days":10,"atC":23},{"life":"out","days":30,"atC":23},{"life":"shelf","months":12,"atC":-18}]},"basis":"SRC: HexPly 8552 sheet and Prepreg Technology storage section. NASA PD-ED-1217 gives the wider range of 10 days to 1 month at room temperature, 6 months to 2 years cold.","sources":["hexcel-8552-us","hexcel-prepreg","nasa-pd-ed-1217"],"tags":["out-life","freezer","tack","kitting"]},{"id":"debulk-cadence","kind":"rule","tier":2,"title":"Debulk cadence during layup","summary":"Vacuum debulk the first ply, then every 3 to 5 layers for 10-15 min at room temperature; every 3 plies on OOA M56; every ply for 5-10 min in sandwich. Tool stays clear for the debulk bag: a part that bridges on debulk bridges on cure.","applies":[],"value":{"min":1,"max":5,"typical":3,"unit":"count"},"basis":"SRC: Hexcel Prepreg Technology; HexPly M56 sheet for OOA and sandwich cadence. EST: the bridging remark is shop reasoning.","sources":["hexcel-prepreg","hexcel-m56","xc110"],"tags":["debulk","layup","ooa"],"see":["composites/process-ooa-vbo"]},{"id":"process-ooa-vbo","kind":"process","tier":2,"title":"Out-of-autoclave and vacuum bag only prepreg","summary":"M56 OOA: full vacuum (-0.95 bar), 1-3 C/min to 110 C, hold 60 min, reduce to -0.5 bar, 1-3 C/min to 180 C, hold 120 min; 1 bar at most consolidates. XC110 asks for 10 mbar or better and about 1000 gsm or less in the stack for a pinhole-free surface.","applies":[],"value":{"table":[{"maxConsolidationBar":1}]},"basis":"SRC: HexPly M56 monolithic cycle; Prepreg Technology for the 1 bar limit; XC110 guide (shop-grade OOA) for vacuum and stack limits. Only rated OOA resins give near-autoclave quality.","sources":["hexcel-m56","hexcel-prepreg","xc110"],"tags":["ooa","vbo","oven"],"detail":"CAD consequences: air must escape in plane, so a long unbroken laminate over 1 m needs edge breathing, and a sealed-off pocket voids. Keep corners open, avoid sharp female radii and thick drop-offs, and expect a thicker cured ply than autoclave: AS4C 285 gsm twill cures at 0.316 mm against Vf 50%, not 55-60%."},{"id":"process-rtm","kind":"process","tier":2,"title":"Resin transfer moulding: closed metal tool, both faces controlled","summary":"RTM: matched metal tool, full vacuum, then inject, usually under 7 bar; RTM6 pot systems to 7 bar, piston units to 30 bar. Void under 1%, 60% fibre volume aim, 2x2 twill and NCF preforms. Both faces are tool faces, so thickness is set by the cavity.","applies":["bracket","suspension","complex small part"],"value":{"table":[{"usualInjectionBar":"< 7","pistonInjectionBar":"to 30","fibreVolumePct":60,"voidPct":"< 1"}]},"basis":"SRC: Hexcel Liquid Composite Moulding manual; RTM6 guidelines for pot and piston limits. EST: the thickness consequence follows from a matched tool.","sources":["hexcel-lcm","hexcel-rtm6"],"tags":["rtm","lcm","preform"],"detail":"CAD consequences: model both faces; add gate and vent positions with a resin path no longer than the gel time allows; resin-rich inlet canals are exotherm risks that Hexcel asks you to size carefully; pre-form with binder. Mould stiffness has to carry injection pressure, so tool walls are heavy. The cavity sets Vf, so the ply count must match the gap or Vf drifts."},{"id":"process-infusion","kind":"process","tier":2,"title":"Resin infusion: one tool face, bag on the other","summary":"Infusion: one tool face and a bag, so atmospheric pressure is the most it can apply (about 1 bar). Flow media spreads resin across the surface, then through thickness. Foam core must suit it: ROHACELL RIST-HT to 180 C and 0.7 MPa.","applies":["large part","boat hull","wind blade"],"value":{"table":[{"maxConsolidationBar":1}]},"basis":"SRC: Hexcel LCM manual for the pressure limit and flow path; Evonik RIST sheet. EST: core-resin-uptake remark from the RIST page, which reports about 50% less uptake than WF.","sources":["hexcel-lcm","evonik-rist"],"tags":["infusion","lri","vari"],"see":["composites/mat-foam-pmi"]},{"id":"process-afp-atl","kind":"process","tier":2,"title":"AFP and ATL: tape widths and curvature set the plybook","summary":"ATL tape 150 or 300 mm for large low-curvature skins; AFP tows 3.175, 6.35, 12.7 mm for complex curvature. Defect-free steering of 1/4 in tow needed a radius of 1350 mm on a woven base ply; narrower tow steers tighter.","applies":["wing skin","fuselage barrel"],"value":{"table":[{"form":"ATL","widthMm":[150,300]},{"form":"AFP","widthMm":[3.175,6.35,12.7]},{"steering":"1/4 in tow","RminMm":1350}]},"basis":"SRC: Hexcel Prepreg Technology widths; Huddersfield study for R 1350 mm (tool and base-ply specific). EST: use that R as a first-pass limit for any 1/4 in tow; machine cut-length limit must come from the machine.","sources":["hexcel-prepreg","afp-limits"],"tags":["afp","atl","steering","automation"]},{"id":"process-filament-winding","kind":"process","tier":3,"title":"Filament winding: fibre paths must be stable on the mandrel","summary":"Winding suits surfaces of revolution. EST: geodesic paths need no friction; off-geodesic paths need slippage below about 0.3-0.4 friction. Mandrel must extract: taper or collapsible. Near-0 deg fibres cannot be wound: use a helical angle or add longitudinal plies.","applies":["pressure vessel","drive shaft","tube"],"value":{"min":0.3,"max":0.4,"unit":"ratio"},"basis":"EST: general winding mechanics, seen in search excerpts only, not an opened page. Hexcel notes single-tow towpreg suits pressure vessels and drive shafts, and that much is SRC.","sources":["hexcel-prepreg"],"tags":["winding","mandrel","geodesic"]},{"id":"process-pultrusion","kind":"process","tier":3,"title":"Pultrusion: constant section, tolerances per ASTM D3917","summary":"Pultrusion gives constant cross-section only. Tolerances: thickness +/-10% with a +/-0.25 mm minimum on angles and channels; flange width and depth +/-4%, up to +/-2.39 mm. A taper, a joggle or a local thick spot means a different process.","applies":["spar cap","rod","tube","stringer"],"value":{"table":[{"dim":"wall t","pct":10,"minMm":0.25},{"dim":"flange b, depth d","pct":4,"maxMm":2.39}]},"basis":"SRC: Strongwell manual section 5 after ASTM D3917, for structural shapes; aerospace rods may hold tighter. EST: that high-performance CAD should follow these numbers until the pultruder states otherwise.","sources":["strongwell-tol"],"tags":["pultrusion","tolerance"]},{"id":"process-compression-smc","kind":"process","tier":2,"title":"Compression moulding: chopped prepreg HexMC","summary":"HexMC 8 x 50 mm chips: 70-100 bar in metal moulds, 150 C for 3 min, 100 C for 40 min, demould hot. Tensile 300 MPa, E 38 GPa, Tg 120 C. Flows into ribs and bosses a laminate cannot make, at a fraction of the strength of tape.","applies":["bracket","housing","rib","boss"],"value":{"table":[{"pressureBar":"70-100","chipMm":"8 x 50","cure":"150 C 3 min"}]},"basis":"SRC: Hexcel HexMC user guide. EST: rib and boss remark is the design consequence of flow moulding, not a rule stated in the guide.","sources":["hexcel-hexmc"],"tags":["compression","smc","chopped"]},{"id":"process-thermoplastic","kind":"process","tier":2,"title":"Thermoplastic composites: stamp, weld, no freezer","summary":"PEEK tape Tp 370-400 C, Tm 343 C, Tg 143 C; LMPAEK Tm 305 C, PEKK 340 C. Indefinite ambient shelf life, so no out-life limit. Continuous compression moulding makes 8-10 mm constant sections. In-situ AFP runs 60-100 mm/s, against 600-700 mm/s plus consolidation.","applies":["clip","bracket","rib","welded stiffener"],"value":{"min":370,"max":400,"unit":"C"},"basis":"SRC: Toray TC1200 sheet; CompositesWorld on PAEK and CCM. EST: stamp-tool and welding CAD consequences (see detail) from general practice.","sources":["toray-tc1200","cw-paek"],"tags":["thermoplastic","peek","paek","stamping","welding"],"detail":"CAD consequences, EST: stamp forming draws a preheated blank into a matched tool, so give generous radii, keep flanges short and avoid double curvature beyond what the fabric can shear. Tool stays below Tc (290 C for PEEK) so the part sets fast and cycle time is minutes. Welding (induction, resistance, ultrasonic) needs a flat faying flange and a clamp path, and replaces bolts or film, so model the weld flange instead of a fastener row. Crystallinity depends on cooling rate, so section-thickness changes affect properties."},{"id":"process-trapped-rubber","kind":"process","tier":3,"title":"Trapped rubber and bladder moulding for closed sections","summary":"EST: trapped rubber makes pressure by silicone expansion in a closed mould, roughly 250 x 10^-6/C against steel at 11-13, so pressure depends on rubber volume, temperature and void space. Inflated bladders apply 1-10 bar autoclave-level pressure and need an open end to extract.","applies":["tube","box section","wishbone","hollow lug"],"value":{"table":[{"rubberCteE6PerC":250,"basis":"EST"}]},"basis":"EST: forum-grade CTE, seen in a search excerpt; Chalmers study confirms the principle without numbers. Steel CTE from a table. Bladder range mirrors the autoclave band as an assumption.","sources":["wiki-cte","hexcel-prepreg"],"tags":["trapped-rubber","bladder","closed-section"],"detail":"CAD consequences: the outer tool is a clamshell with a parting line that crosses the laminate, so plan the seam and its overlap. The inner surface has no tool: tolerance it loosely and inspect by ultrasonic. Design the section so the bladder or mandrel comes out: no re-entrant waist, and an opening at one end at least. Do not model an inside fillet tighter than the bladder can reach."},{"id":"process-cut-kit-project","kind":"process","tier":3,"title":"Ply cutting, kitting and laser projection","summary":"Nest and cut plies by CNC, label by ply number and sequence, kit per part so the 30-day out-life is spent on layup. EST: projectors place ply edges to about 0.5 mm, so a CAD ply boundary within 1 mm of a neighbour is not repeatably achievable by hand.","applies":[],"value":{"typical":0.5,"unit":"mm"},"basis":"EST: projector accuracy and the 1 mm remark are practice with no opened source; check your projector. SRC: 30-day out-life; sharp-tool cutting from Hexcel.","sources":["hexcel-prepreg","hexcel-8552-us"],"tags":["cutting","kitting","laser-projection","plybook"]},{"id":"tool-material-cte","kind":"material","tier":1,"title":"Tool materials and CTE mismatch","summary":"CTE in 10^-6/C: Invar 1.2, HexTool BMI 4 in plane (47 through thickness), steel 11-13, aluminium 23.1. Part fibre direction near 0 to 2. Over 157 K cure rise, an aluminium metre grows about 3 mm more than carbon. Use Invar or CFRP for long, close parts.","applies":["tool","mould","mandrel"],"value":{"table":[{"tool":"Invar 36","cte":1.2,"gcc":8.05,"use":"long, close-tolerance, high cycles"},{"tool":"CFRP / BMI (HexTool M61)","cte":4,"zCte":47,"use":"low mass, up to 500 cycles reported"},{"tool":"carbon steel","cte":10.8,"use":"short parts, RTM, press"},{"tool":"aluminium","cte":23.1,"use":"small parts, prototypes, fast heat-up"}]},"basis":"SRC: Wikipedia CTE tables; HexTool M61 guide; CompositesWorld for suitability and the 500-cycle HexTool claim (a supplier claim). EST: mismatch arithmetic (23.1 - 2) x 157 K x 1 m, and fibre-direction 0-2 from the sign of Toray fibre CTE plus resin.","sources":["wiki-cte","wiki-invar","hexcel-hextool","cw-tooling"],"tags":["tooling","invar","cfrp-tool","steel","aluminium"]},{"id":"tool-compensation","kind":"rule","tier":2,"title":"Scale the tool for its CTE mismatch with the part","summary":"A tool surface at cure temperature is what the part freezes to. Scale a tool length by 1 - (a_tool - a_part) x dT: about 3.3 mm per metre for aluminium at 157 K rise. Invar under 0.2 mm per metre. Prototype metal tools need this; do not model part size on the tool.","applies":[],"value":{"typical":3.3,"unit":"mm"},"basis":"EST: first-order thermal arithmetic with SRC CTE values, ignoring the resin gel point (taking the cure temperature as the set point is the conservative assumption). DLR warns low-cost tools shift final shape; that excerpt was not opened.","sources":["wiki-cte","wiki-invar"],"tags":["tooling","scale","cte"]},{"id":"spring-in","kind":"rule","tier":1,"title":"Spring-in on curved sections: compensate the tool angle","summary":"Curved laminates close up on cooling: d_theta = theta x (a_in - a_thru) x dT. FE on 12 ply cross-ply OoA carbon gave 0.2 deg; the measured spar gave 0.5-0.8 deg; a 90 deg corner with 38 x 10^-6 CTE gap and 157 K gives about 0.5 deg. Open the tool angle; iterate.","applies":[],"value":{"min":0.2,"max":0.5,"unit":"deg"},"basis":"SRC: Radford-form equation and 0.18-0.26 deg results, Osmeda 2012. EST: the 0.5 deg arithmetic using resin-dominated through-thickness CTE from that paper. EST: steel or Invar choice has a smaller effect than layup. The paper measured 0.5-0.8 deg against 0.18-0.26 deg predicted.","sources":["osmeda-2012"],"tags":["distortion","compensation"],"see":["composites/tool-material-cte"]},{"id":"tool-draft-release","kind":"rule","tier":2,"title":"Tool draft and release on a one-sided mould","summary":"EST: give female tools 3 deg draft and allow 1 deg on male tools where the part shrinks away from it; a male Invar tool grips the part as it cools. Reseal the tool after 25-50 cure cycles for easy release. Heat-cycle every new tool before first use.","applies":[],"value":{"min":1,"typical":3,"unit":"deg"},"basis":"EST: draft figures are shop practice; no opened source gives one. SRC: reseal cadence (HexTool guide) and heat-cycling (Hexcel prepreg manual).","sources":["hexcel-hextool","hexcel-prepreg"],"tags":["draft","release","tooling"]},{"id":"tool-surface-allowance","kind":"dimension","tier":3,"title":"Machined tool stock and laminated tool allowances","summary":"HexTool M61: rough machine to +2.54 mm then finish; 2000 g/m2 ply cures 1.25 mm, machines to 0.97 mm per ply. IML masters give about 1.27 mm per ply; OML masters 0.89 mm. Typical finished tool 9.5 mm thick. Splice overlap at least 12 mm, shifted 50 mm per layer.","applies":[],"value":{"typical":2.54,"unit":"mm"},"basis":"SRC: Hexcel HexTool user guide values. EST: applying the same offset logic to board and metal tools, where the machinist sets the stock.","sources":["hexcel-hextool"],"tags":["tool-allowance","machining","master"],"see":["composites/master-pattern"]},{"id":"master-pattern","kind":"note","tier":3,"title":"Master pattern and tooling board route","summary":"Machine a master in tooling board or foam, seal it, lay up the BMI or epoxy tool on it, cure (M61: 190 C), post-cure out of autoclave (220 C), then finish-machine. CAD: model the part, offset to the tool face, then add stock and a flange for the bag seal.","applies":[],"basis":"SRC: Hexcel HexTool guide route (foam, metal or composite masters; M61 cure and post-cure temperatures); tooling board is not named there; board temperature rating is the supplier sheet and is not stated here. EST: the CAD sequence.","sources":["hexcel-hextool"],"tags":["master","tooling-board","tool"]},{"id":"tool-vacuum-integrity","kind":"tolerance","tier":3,"title":"Vacuum integrity limits for a cure bag","summary":"Hexcel tooling-fabric cure: at least 22 inHg (0.7 bar) and leak no more than 2 inHg in 10 min, heat at most 5 F/min to 300 F. Reduce applied vacuum after pressurising as a live leak check. Design seal land and port room into the tool.","applies":[],"value":{"table":[{"minVacuumInHg":22,"maxLeakInHg":2,"overMin":10,"maxHeatFPerMin":5}]},"basis":"SRC: Hexcel tooling fabrics guide (tool layup, not part cure); Prepreg Technology for the reduced-vacuum leak check. EST: extending these to part bags.","sources":["hexcel-toolfab","hexcel-prepreg"],"tags":["vacuum","leak","bag"]},{"id":"layup-symmetric-balanced","kind":"rule","tier":1,"title":"Symmetric and balanced stacking","summary":"Stack symmetric about the mid-plane so B = 0 and the part does not warp on cool-down; pair +theta with -theta so A16 = A26 = 0. The laminate calculator warns B_NOT_ZERO, A16_A26_NOT_ZERO, D16_D26_NOT_ZERO. A +/-theta pair in a symmetric stack takes at least 4 plies.","applies":[],"value":{"options":["B_NOT_ZERO","A16_A26_NOT_ZERO","D16_D26_NOT_ZERO"]},"basis":"SRC: DLR guideline review, symmetric and balance definitions; warning names from the tool help topic in this repo. EST: the 4-ply count is arithmetic (+theta, -theta, mirrored), not stated by DLR.","sources":["dlr-laminate","nas1-19347"],"tags":["warpage"]},{"id":"layup-ten-percent","kind":"rule","tier":1,"title":"The 10% rule","summary":"At least 10% of the fibres in each of 0, +45, -45 and 90, so a secondary load does not meet a matrix-dominated direction. For optimised laminates, a stiffness-based generalised form exists. A pure 0/90 or all-UD skin fails this.","applies":[],"value":{"min":10,"unit":"%"},"basis":"SRC: DLR thesis review of laminate guidelines, citing Abdalla 2009 for the generalised form.","sources":["dlr-laminate","nas1-19347"],"tags":["stacking"],"see":["aerospace/cf-layup-basics"]},{"id":"layup-contiguity-disorientation","kind":"rule","tier":2,"title":"Blocked plies, disorientation and outer plies","summary":"Keep contiguous same-angle plies under 0.6 mm: 4 or 5 standard plies. Step at most 45 deg between adjacent plies. Put +/-45 on the outer faces for impact and free-edge behaviour, with a 0 or 90 separating them if disorientation requires.","applies":[],"value":{"max":0.6,"unit":"mm"},"basis":"SRC: DLR thesis review; states the 0.6 mm practice and that free-edge stress grows with contiguous thickness.","sources":["dlr-laminate"],"tags":["contiguity","disorientation","outer-ply"]},{"id":"layup-min-gauge","kind":"dimension","tier":2,"title":"Minimum gauge for a balanced laminate","summary":"EST: smallest balanced symmetric carbon skin is [+/-45]s, 4 plies: about 0.5 mm of 0.125 mm tape, 0.73 mm of 0.183 mm tape, or 2 fabric plies 0.4-0.6 mm. Below about 1 mm it loses impact tolerance and cannot take a countersink; hold 1.5 mm at fasteners.","applies":[],"value":{"min":0.5,"typical":1,"unit":"mm"},"basis":"EST: derived from ply thicknesses SRC here. The 1 mm and 1.5 mm impact and fastener floors are practice, not from an opened source; damage-tolerance test should set them.","sources":["ncamp-im7-8552","hexcel-hsd"],"tags":["min-gauge","thickness"]},{"id":"ply-drop-stagger","kind":"rule","tier":1,"title":"Ply drop spacing and stagger","summary":"Space dropped plies at least 3 ply thicknesses apart (0.55 mm of IM7/8552); that is the floor. Fewest drops per station, cut inner plies first, 0 before 90, keep symmetry, and never drop adjacent 0 and 90.","applies":[],"value":{"min":3,"unit":"ratio"},"basis":"SRC: Obata 2021 list of published guidelines for the 3t, order and symmetry rules.","sources":["obata-2021","nas1-19347"],"tags":["taper"],"see":["composites/ply-drop-taper"]},{"id":"ply-drop-taper","kind":"rule","tier":1,"title":"Thickness taper ratio","summary":"Taper at 20:1 along primary load paths and 10:1 for secondary paths and for stiffener or flange run-outs. Each dropped 0.183 mm ply takes at least 3.66 mm of run at 20:1. 20:1 is the safe first model.","applies":[],"value":{"min":10,"typical":20,"unit":"ratio"},"basis":"EST: 20:1 and 10:1 from NASA contract NAS1-19347 guideline text seen in a search excerpt; the report itself was not opened. Arithmetic with SRC ply thickness.","sources":["nas1-19347","ncamp-im7-8552"],"tags":["ramp"]},{"id":"inside-radius","kind":"rule","tier":1,"title":"Minimum inside radius","summary":"EST: inside radius at least 2 x laminate thickness and never under 3 mm for prepreg on a female tool; tighter corners bridge, resin-pool and open under curved-beam tension. Corner thickness also rises on a female tool and thins on a male.","applies":[],"value":{"min":3,"unit":"mm"},"basis":"EST: shop and guideline practice; no opened source gives a minimum radius. Female-tool thickening and male-tool thinning match search excerpts, not opened. Check with a coupon on your system.","sources":["hexcel-prepreg"],"tags":["corner","bridging"]},{"id":"drape-shear-limit","kind":"rule","tier":1,"title":"Drape: shear angle limit and fabric choice","summary":"EST: woven plies shear before they wrinkle, up to a locking angle near 35-50 deg by weave and temperature. Design to under 30 deg at first pass. Satin drapes best, twill next, plain worst. UD tape has essentially no drape: split it or use a fabric on double curvature.","applies":[],"value":{"max":30,"unit":"deg"},"basis":"EST: all degree figures. Search excerpts confirm a locking angle exists and varies, but no opened paper tabulated it; use cad_flatten_surface or a picture-frame test. SRC: weave ranking, Hexcel Prepreg Technology.","sources":["hexcel-prepreg"],"tags":["wrinkle","locking-angle"]},{"id":"darts-splices","kind":"rule","tier":2,"title":"Darts, splices and overlaps","summary":"EST: butt splice UD with 0 gap and no overlap; overlap fabric 12-25 mm. Stagger splices through the stack by at least 50 mm, never above one another, and keep them off radii. Place a dart where the shear map exceeds the drape limit, and stay out of the primary load path.","applies":[],"value":{"min":12,"max":25,"unit":"mm"},"basis":"SRC: 12 mm minimum overlap, 50 mm shift and not on a radius, from Hexcel HexTool guide (tooling plies). EST: transferring to part plies; the 25 mm upper figure and UD butt practice.","sources":["hexcel-hextool"],"tags":["dart","splice","overlap","plybook"]},{"id":"void-content","kind":"tolerance","tier":2,"title":"Void content a process delivers","summary":"Hexcel quotes under 1% voids for RTM. EST: autoclave under 1%, VBO about 1-2%, wet-bag or infusion higher. EST: ILSS falls about 2-8% per 1% void, so state a void limit on the drawing and verify by C-scan or acid digestion.","applies":[],"value":{"max":1,"typical":1,"unit":"%"},"basis":"SRC: RTM under 1% only. EST: other classes and ILSS slopes from search excerpts of studies not opened; slopes vary by material, so treat as an order of magnitude.","sources":["hexcel-lcm","hexcel-prepreg"],"tags":["void","porosity","quality"]},{"id":"thermal-residual-note","kind":"note","tier":3,"title":"Why unsymmetric layups warp and how to live with one","summary":"An unsymmetric layup bows on cool-down because the CTE mismatch between plies acts through B. Where a one-sided feature forces it (an outer cosmetic ply), balance with a matching ply on the far face or accept and stiffen.","applies":[],"basis":"EST: classical laminate theory consequence, no specific number.","sources":[],"tags":["warp","unsymmetric"]},{"id":"bolted-joint-geometry","kind":"fastener","tier":2,"title":"Bolted joints: edge distance, pitch, thickness","summary":"EST: e/D at least 3 and side distance at least 2.5D to avoid shear-out and cleavage; pitch at least 5D. Coupons test w/D 6, so w/D under 6 gives lower-than-table strength. Use quasi-isotropic with +/-45 near holes, and 2.0 factor around fasteners.","applies":["lug","bolted flange","skin splice"],"value":{"table":[{"ratio":"e/D","min":3},{"ratio":"side/D","min":2.5},{"ratio":"pitch/D","min":5},{"ratio":"w/D (coupon)","value":6}]},"basis":"EST: e/D and pitch, from a practitioner thread and a study abstract in search excerpts, not opened; CMH-17 not read. SRC: w/D 6 baseline, CompositesWorld; 2.0 factor, NASA.","sources":["cw-bolted","nasa-pd-ed-1217","eng-tips-bolted"],"tags":["bolted","edge-distance","e/d","w/d","pitch","bearing"],"see":["hardware/edge-distance-holes"]},{"id":"countersink-depth","kind":"rule","tier":3,"title":"Countersink limit in laminate","summary":"EST: keep countersink depth at or under 2/3 of laminate thickness; a knife-edge hole loses bearing and fatigue. Use a 100 deg tension-head only where the skin carries it, and a metal doubler if the skin is thinner than the head plus a margin.","applies":[],"value":{"max":0.67,"unit":"ratio"},"basis":"EST: 2/3 figure from a practitioner thread in a search excerpt; the page refused a direct fetch. 100 deg is the common aerospace head angle, not from an opened source.","sources":["eng-tips-bolted"],"tags":["countersink","fastener"],"see":["hardware/countersink-iso-10642"]},{"id":"potted-insert","kind":"fastener","tier":2,"title":"Potted and bonded inserts in sandwich","summary":"Potted insert: core depth over face thickness above 10 for the standard method, 1.15 fitting factor, outer flange without chamfer on a thin CFRP skin, and flange parallel to skin. Bracket foot must overhang the potting. Use insert pairs to carry torsion.","applies":["sandwich panel","satellite panel","floor"],"value":{"min":10,"unit":"ratio"},"basis":"SRC: Abbott AA-SB-001 12.2.6 summary of ECSS-E-HB-32-22A and ESA-PSS-03-1202; that source warns of errors in the ECSS numerics. Non-metal torsion strength is by test.","sources":["abbott-inserts"],"tags":["insert","potted","sandwich","core-excavation"],"detail":"Process: drill one or both skins, excavate core beyond the hole, inject potting. Effective radius has separate forms for perforated and non-perforated core. Excavation changes mass: the potting pill is often the heaviest local detail, so model it for mass. For foam, the same method applies but estimate excavation conservatively. Edge support at the skin hole matters because in-plane loads pass by bearing between outer flange and skin. Spreadsheets AA-SM-140 cover the calculation; the equation images were not reproduced here."},{"id":"bonded-lap-joint","kind":"rule","tier":2,"title":"Lap and joggled bonded joints","summary":"EST: overlap at least 30 t for a structural double lap; adherend ends tapered and the resin fillet kept. Hexcel says leave the squeeze-out and taper the overlap ends. Standard lap-shear coupon is 1.63 mm alloy with 12.5 mm overlap: not a design overlap. Joggle at 10:1 slope.","applies":[],"value":{"typical":30,"unit":"ratio"},"basis":"EST: 30 t and the joggle slope are practice; this figure was not located in the Hart-Smith report I opened. SRC: fillet and taper advice, coupon size, Hexcel bonding manual.","sources":["hexcel-bonding"],"tags":["lap","joggle","bond"]},{"id":"scarf-joint","kind":"rule","tier":2,"title":"Scarf and step joints","summary":"Repair scarf tapers usually 30-60:1; step-sanded repair 25-50 mm per layer. Scarf bond strength keeps rising with overlap, unlike a lap, so a shallow scarf can carry full laminate strength at the cost of area. EST: 20:1 is the steepest for a new-build joint.","applies":[],"value":{"min":30,"max":60,"unit":"ratio"},"basis":"SRC: taper and step, Hexcel Composite Repair; overlap behaviour, Hart-Smith NASA CR-112237. EST: 20:1 from a 1:20 scarfed study seen in search excerpts.","sources":["hexcel-repair","hart-smith-cr112237"],"tags":["scarf","stepped","bond","repair"]},{"id":"surface-prep-bond","kind":"rule","tier":2,"title":"Surface preparation before bonding","summary":"Laminate: peel ply removed just before bonding, or grit blast at 125-315 um. Degrease first, abrade, remove loose particles, bond while active. Water-break test: a continuous film for at least the drain means clean. NASA adds FTIR, NVR, XRF and ellipsometry checks.","applies":[],"value":{"min":125,"max":315,"unit":"um"},"basis":"SRC: Hexcel bonding manual; NASA PD-ED-1217 verification methods. Peel-ply surface limits (reduced strength in some cases) are noted by Hexcel; no number stated.","sources":["hexcel-bonding","nasa-pd-ed-1217"],"tags":["surface","peel-ply","grit-blast","water-break"]},{"id":"bondline-control","kind":"dimension","tier":3,"title":"Bondline thickness control","summary":"Use carrier or microsphere film adhesive so the bond stays at a set minimum under pressure. EST: target 0.1-0.25 mm in CAD: tool the gap, do not rely on squeeze-out. Test tabs tolerate 1-2 mm because they want to reduce peak stress, not carry a joint.","applies":[],"value":{"min":0.1,"max":0.25,"unit":"mm"},"basis":"EST: 0.1-0.25 mm, typical film adhesive practice; no opened sheet states it. SRC: carrier and microsphere control, Hexcel bonding manual; 1-2 mm tab bondline, CompositesWorld.","sources":["hexcel-bonding","cw-tension"],"tags":["bondline","adhesive","gap"]},{"id":"sandwich-wrinkling","kind":"rule","tier":1,"title":"Face wrinkling check","summary":"Wrinkling stress = 0.5 x (Gc Ec Ef)^(1/3). For a 60 GPa face on HRH-10 48 (GW 25, Ec 138 MPa): 296 MPa. Compare with compressive face stress = M / (h tf b). Needs high Ec and flatwise bond strength. Hexcel calls classical forms order-of-magnitude.","applies":[],"value":{"table":[{"formula":"0.5*(Gc*Ec*Ef)^(1/3)","units":"MPa"}]},"basis":"SRC: Hexcel AGU 075b Appendix III formula, for symmetric thin facings on a core much softer than skins. EST: worked number. Study excerpts report classical forms conservative on CFRP.","sources":["hexcel-hsd"],"tags":["skin"]},{"id":"sandwich-dimpling","kind":"rule","tier":2,"title":"Intra-cell buckling (face dimpling)","summary":"Intra-cell stress = 2 Ef (tf/s)^2. A 60 GPa, 0.25 mm face on a 3.2 mm cell: 730 MPa; on 6.4 mm: 183 MPa. Large cells with thin skins also telegraph on the outer surface, so cell size is a surface-finish choice too.","applies":[],"value":{"table":[{"formula":"2*Ef*(tf/s)^2","units":"MPa, mm"}]},"basis":"SRC: Hexcel AGU 075b Appendix III and cell-size remarks. EST: worked numbers.","sources":["hexcel-hsd"],"tags":["sandwich","dimpling","intracell","cell-size"]},{"id":"sandwich-core-shear","kind":"rule","tier":2,"title":"Core shear, shear crimping and local crush","summary":"Core shear = F / (h b), h = tf + tc. Check against FsW on hexagonal core: W is about 0.6 of L. Crimping load per width = tc Gc. Local compression = P / A against Fc: HRH-10 48 gives 2.4 MPa, so a 1 kN point load needs at least 417 mm2 of pad.","applies":[],"value":{"typical":0.6,"unit":"ratio"},"basis":"SRC: Hexcel AGU 075b Appendix III; shear deflection cannot be neglected with low core modulus. EST: 0.6 ratio read from HRH-10 and 5052 rows; pad arithmetic.","sources":["hexcel-hsd"],"tags":["sandwich","core-shear","crimping","crush","local-load"]},{"id":"sandwich-stiffness-benefit","kind":"rule","tier":3,"title":"What a core buys: stiffness per weight","summary":"Against a solid panel, Hexcel shows cored panels at 7 times stiffness and 3.5 strength for 1.03 weight, and 37 times stiffness, 9.2 strength for 1.06 weight. Deflection must add a shear term, F l / S, with S = b h Gc: do not use bending alone.","applies":[],"value":{"table":[{"stiffness":7,"strength":3.5,"weight":1.03},{"stiffness":37,"strength":9.2,"weight":1.06}]},"basis":"SRC: Hexcel AGU 075b Figure 2 and Appendix III. The figure gives ratios; the panel thicknesses it draws were not in the extracted text, so none are stated here.","sources":["hexcel-hsd"],"tags":["sandwich","stiffness","weight"]},{"id":"core-edge-ramp","kind":"rule","tier":2,"title":"Core edge ramp angle and close-outs","summary":"EST: ramp honeycomb at 20-30 deg and foam up to 45 deg, so autoclave side pressure does not crush it. Hold a ramped core with film or foaming adhesive. Square edges: close with filler, box extrusion, Z or U section. Exposed edges are damage and moisture routes.","applies":[],"value":{"min":20,"max":45,"typical":30,"unit":"deg"},"basis":"EST: all ramp angles are practice; no opened source gave them. HexWeb Attributes covers crush but not a ramp angle. SRC: closure types and why, Hexcel AGU 075b p23.","sources":["hexcel-hsd","hexcel-attrib"],"tags":["core","ramp","chamfer","close-out","crush"]},{"id":"core-forming","kind":"rule","tier":3,"title":"Forming honeycomb: anticlastic curvature and OX","summary":"Hexagonal core bends with reversed curvature at 90 deg (anticlastic); OX core, overexpanded to about 2:1 W:L, curves far better, and Flex-Core better still. Standard sheet 48 x 96 in, 0.125 in minimum slice. Machine a thick slice rather than bending at tight radius.","applies":[],"value":{"typical":2,"unit":"ratio"},"basis":"SRC: Hexcel Attributes, AGU 075b and HRH-10 sheet. EST: the advice to machine rather than form at a tight radius.","sources":["hexcel-attrib","hexcel-hsd","hexcel-hrh10"],"tags":["core","honeycomb","ox-core","anticlastic"]},{"id":"sandwich-production-route","kind":"process","tier":3,"title":"Sandwich production: co-cure, press or secondary bond","summary":"Three routes: heated press for flat, vacuum bag for curved, matched mould for tolerance. Honeycomb autoclave pressure must avoid core crush; a 1 atm oven suffices for rated OOA. Compact after every ply on OOA sandwich for 5-10 min. Precured skins bond with film adhesive.","applies":[],"value":{"table":[{"compactMin":"5-10","perPly":1}]},"basis":"SRC: Hexcel AGU 075b p21-22, Prepreg Technology, M56 sheet. Skin dimpling into cells on co-cure is why thin faces often precure: EST inference.","sources":["hexcel-hsd","hexcel-prepreg","hexcel-m56"],"tags":["sandwich","co-cure","press"]},{"id":"first-vs-last-ply","kind":"rule","tier":2,"title":"First-ply failure and last-ply: what to report","summary":"cad_design_knowledge laminate runs max-strain first-ply at both ply faces; ratio under 1 passes. Treat first-fibre failure as ultimate on a fibre-dominated, 10% rule laminate. Matrix first-ply cracking can come well below that; includeMatrix:true adds it to the check.","applies":[],"value":{"max":1,"unit":"ratio"},"basis":"SRC: tool behaviour from repo help topic. EST: the fibre-dominated first-ply convention is practice; laminate-level last-ply needs degrading ply stiffness, which the tool does not do.","sources":["ncamp-im7-8552"],"tags":["first-ply","last-ply","failure","max-strain"],"see":["composites/first-pass-allowable-choice"]},{"id":"edge-trim","kind":"tolerance","tier":2,"title":"Edge trim and machining of cured laminate","summary":"Cut with diamond abrasive or PCD, not HSS. HexTool: rough 40/60 diamond cutter leaving +2.54 mm, finish 80/120 grit, 2.03-2.54 m/min feed, 0.38-0.64 mm per pass, 457-548 m/min surface speed. EST: seal trimmed edges; router holds +/-0.25 mm, waterjet slightly worse with taper.","applies":[],"value":{"typical":0.25,"unit":"mm"},"basis":"EST: the 0.25 mm tolerance and edge sealing are practice. SRC: HexTool machining values, for a thick BMI tool and not a thin skin.","sources":["hexcel-hextool"],"tags":["trim","router","machining","edge"]},{"id":"drilling-exit-delamination","kind":"rule","tier":2,"title":"Drilling: exit delamination","summary":"Push-out at the exit is the main hole defect. EST: back up the exit with a sacrificial plate, run carbide or PCD at low feed (0.05 mm/rev), peck thick stacks. Finish a tight hole by reamer. Keep hole 3D from free edge; ply peel at entry is also a limit. Inspect 100% at first.","applies":[],"value":{"typical":0.05,"unit":"mm"},"basis":"EST: feed and method from drilling review excerpts, not opened; check with a trial stack. SRC: 100% inspection early, NASA. Hole edge rule from bolted-joint-geometry.","sources":["nasa-pd-ed-1217"],"tags":["drilling","delamination","exit","backup","hole"],"see":["composites/bolted-joint-geometry","aerospace/cf-epoxy-plate"]},{"id":"test-ultrasonic-cscan","kind":"test","tier":2,"title":"Ultrasonic C-scan and A-scan","summary":"Ultrasound maps internal porosity, inclusions and delaminations; Start at 100% in-process NDT, reducing to problem areas (NASA). Geometry: needs a smooth, parallel, reachable surface and 2-sided access for through-transmission. Tight radii and ramps need a tailored probe.","applies":[],"value":{"typical":100,"unit":"%"},"basis":"SRC: Hexcel prepreg manual; NASA PD-ED-1217 for inspection reduction. EST: 2-sided access and curved-part remarks from general NDT practice.","sources":["hexcel-prepreg","nasa-pd-ed-1217"],"tags":["ndt","ultrasonic","c-scan","porosity"]},{"id":"test-thermography-tap","kind":"test","tier":3,"title":"Thermography, radiography and tap test","summary":"Thermography finds near-surface porosity and disbonds with 1-side access, suiting a sandwich skin. NASA also lists radiography, eddy current and acoustic emission. Tap test: a dull note maps damage. Sandwich disbonds need a pull-off at 1 sample per batch or a tag.","applies":[],"value":{"typical":1,"unit":"count"},"basis":"EST: the per-batch tag frequency and 1-side remark. SRC: methods from NASA PD-ED-1217 and Hexcel Composite Repair.","sources":["nasa-pd-ed-1217","hexcel-repair","hexcel-prepreg"],"tags":["ndt","thermography","tap-test"]},{"id":"repair-options","kind":"process","tier":2,"title":"Repair: patch, scarf, step, and core plug","summary":"Remove damage plus typically 12.5 mm into sound skin, dry the part, replace core with splice adhesive. Patch thickens; scarf 30-60:1 is flush; step 25-50 mm per layer. Add an extra ply. Design access, and leave edge margin so a scarf at 30:1 fits: 1 mm of skin needs 30 mm.","applies":[],"value":{"typical":12.5,"unit":"mm"},"basis":"SRC: Hexcel Composite Repair UTC 102; aircraft must follow the SRM. EST: the margin arithmetic and that CAD should plan for it.","sources":["hexcel-repair"],"tags":["repair","scarf","patch","core-plug"]},{"id":"test-tension-d3039","kind":"test","tier":2,"title":"ASTM D3039 tension coupon","summary":"Width 10-15 mm for 0 deg UD, 25 mm for 90 deg UD and balanced laminates. Tabs: 7-10 deg taper, untapered length at least 40 mm, tab bondline 1-2 mm reduces peak stress. Textile width at least 2 unit cells (ASTM D6856).","applies":[],"value":{"min":10,"max":25,"unit":"mm"},"basis":"SRC: CompositesWorld Adams columns stating D3039 figures. Standard itself paywalled: length not confirmed here.","sources":["cw-tension","cw-textile","astm-composites"],"tags":["d3039","tension","coupon"]},{"id":"test-compression-d6641","kind":"test","tier":2,"title":"ASTM D6641 combined-loading compression coupon","summary":"D6641: 140 mm long, 13 mm gauge, up to 30 mm wide, unlike D3410 at 13 mm UD width. Thickness by buckling equation plus 10-20%. So a compression test panel must be thick enough: too thin a UD panel buckles rather than fails.","applies":[],"value":{"typical":140,"unit":"mm"},"basis":"SRC: CompositesWorld Adams column for both standards; standard paywalled.","sources":["cw-compression","astm-composites"],"tags":["d6641","d3410","compression","coupon"]},{"id":"test-shear-d3518","kind":"test","tier":2,"title":"In-plane shear: D3518, D5379, D7078","summary":"D3518 tests a +/-45 laminate in tension (combined stress, simplest). D5379 V-notch 76 x 19 mm; D7078 rail shear 76 x 56 mm. Plan the coupon sheet from those sizes; +/-45 needs a balanced panel, and the G12 values here are from this kind of test.","applies":[],"value":{"table":[{"method":"D5379","mm":"76 x 19"},{"method":"D7078","mm":"76 x 56"}]},"basis":"SRC: CompositesWorld Adams columns; standard paywalled.","sources":["cw-shear","cw-textile","astm-composites"],"tags":["d3518","d5379","d7078","shear"]},{"id":"test-impact-cai","kind":"test","tier":2,"title":"D7136 impact and D7137 compression after impact","summary":"CAI plate 100 x 150 mm, 4-6 mm thick, balanced symmetric, [45/90/-45/0]ns for comparison, 8 mm end supports. So a CAI panel at 0.183 mm ply needs about 24-32 plies, regardless of the part gauge. Energy is often picked for barely visible damage. Not a direct allowable.","applies":[],"value":{"min":4,"max":6,"unit":"mm"},"basis":"SRC: CompositesWorld Adams on D7137. EST: ply count arithmetic. Typical energy values not stated in opened source.","sources":["cw-cai","astm-composites","hexcel-8552-us"],"tags":["d7136","d7137","cai","impact","damage-tolerance"],"detail":"HexPly 8552 CAI reference: QI 25/50/25, AS4 34.6 ksi, IM7 31 ksi at 77 F dry; AS4 at 1500 in-lb/in impact 32 ksi. If design strain is checked against a CAI strength, a QI at about 31 ksi over 8.35 Msi gives about 0.0037 strain, lower than the open-hole compression 0.0043: on an exposed part CAI can govern, so do not skip it. NCAMP removed its IM7 CAI data as a test anomaly, so this comparison uses the Hexcel sheet value with the NCAMP modulus."},{"id":"test-mode1-d5528","kind":"test","tier":2,"title":"ASTM D5528 mode I DCB coupon","summary":"DCB needs a unidirectional panel with a mid-plane film insert no thicker than 13 um, placed during layup. PTFE suits epoxy cured at 177 C or below. So order the insert before layup; it cannot be retrofitted.","applies":[],"value":{"max":13,"unit":"um"},"basis":"SRC: CompositesWorld Adams citing D5528. Specimen length not confirmed in opened source, so not stated.","sources":["cw-fracture","astm-composites"],"tags":["d5528","dcb","mode-i","fracture"]},{"id":"test-open-hole-d5766","kind":"test","tier":2,"title":"D5766 open-hole tension and D6484 open-hole compression","summary":"Baseline 36 mm wide with a 6 mm hole, w/D 6. D5766 failure must pass through the hole. D6742 filled-hole notched strength is usually higher, so joint analysis uses open-hole. IM7/8552 QI: OHT 57.75 ksi CTD mean, OHC 35.52 ksi ETW mean.","applies":[],"value":{"table":[{"widthMm":36,"holeMm":6,"wOverD":6}]},"basis":"SRC: CompositesWorld Adams; values NCAMP. Failure location rule from an Instron summary in a search excerpt, the page refused direct fetch.","sources":["cw-bolted","ncamp-im7-8552","astm-composites"],"tags":["d5766","d6484","open-hole","oht","ohc"],"see":["composites/recipe-open-hole-coupon"]},{"id":"test-bearing-d5961","kind":"test","tier":3,"title":"D5961 bearing and D7248 bearing-bypass","summary":"D5961: 4 procedures; A and D double shear, B and C single or double fastener single shear. D7248 high bearing, low bypass, about 50:50 load per bolt. IM7/8552 QI single-shear 2% offset: RTD 98.08 ksi B, ETW 65.05.","applies":[],"value":{"table":[{"condition":"RTD","ksi2pctB":98.08},{"condition":"ETW","ksi2pctB":65.05}]},"basis":"SRC: CompositesWorld Adams; NCAMP Table 3-4 SSB row; the PDF text layout is scrambled, so verify on the NCAMP page before quoting.","sources":["cw-bolted","ncamp-im7-8552","astm-composites"],"tags":["d5961","d7248","bearing"]},{"id":"test-sandwich-coupons","kind":"test","tier":3,"title":"Sandwich tests: flexure, shear, peel","summary":"Long beam flexure typical span 20 in; short beam 4 in for core shear; edgewise compression; climbing drum peel. Plate shear per AMS-STD-401 at 0.5 in core: thicker core gives lower shear strength than a datasheet, so correct for thickness above 0.5 in.","applies":[],"value":{"table":[{"test":"long beam","spanIn":20},{"test":"short beam","spanIn":4}]},"basis":"SRC: Hexcel Mechanical Testing of Sandwich Panels; HRH-10 sheet. EST: the thickness-trend wording; the sheet states only that the test is at 0.5 in.","sources":["hexcel-sandwich-test","hexcel-hrh10"],"tags":["sandwich","flexure","peel","core-shear-test"]},{"id":"test-ilss-sbs","kind":"test","tier":3,"title":"Short-beam shear D2344 as process control","summary":"SBS on IM7/8552: 17.13 ksi RTD mean, 8.25 ksi ETW. Tag ends cured with a part make SBS and Tg coupons cheap, so leave a 25 mm tag band outside the net trim. It is a QC number, not a design allowable.","applies":[],"value":{"typical":25,"unit":"mm"},"basis":"EST: 25 mm band and the QC framing. SRC: NCAMP Table 3-3 and tag-end practice, NASA PD-ED-1217.","sources":["ncamp-im7-8552","nasa-pd-ed-1217"],"tags":["d2344","sbs","qc","tag"]},{"id":"hot-wet-tg","kind":"rule","tier":3,"title":"Hot/wet: moisture and Tg margin","summary":"Epoxy can absorb up to 5% water by weight. 8552: Tg 392 F dry, 309 F wet (RDS), service up to 250 F; NCAMP wet Tg 321 F. EST: keep at least 28 C (50 F) between wet Tg and maximum service. Matrix E2 falls to 62% and G12 to 46% at 250 F wet.","applies":[],"value":{"min":28,"unit":"C"},"basis":"EST: the 28 C margin is common practice with no opened source. SRC: NASA PD-ED-1217, HexPly 8552, NCAMP. Ratios are NCAMP E2 0.81/1.30, G12 0.31/0.68.","sources":["nasa-pd-ed-1217","hexcel-8552-us","ncamp-im7-8552"],"tags":["hot-wet","tg","moisture"]},{"id":"matrix-service-table","kind":"material","tier":3,"title":"Matrix choice by service temperature","summary":"Service limits: phenolic 80-100 C (fire); 120 C-cure epoxy 100 C; 180 C-cure epoxy 130-155 C; BMI and polyimide to 260 C. Higher cure rating means a tool surviving that cure: an epoxy tool does not survive repeated 177 C cycling.","applies":[],"value":{"table":[{"matrix":"phenolic","maxC":"80-100"},{"matrix":"120 C epoxy","maxC":"100"},{"matrix":"180 C epoxy","maxC":"130-155"},{"matrix":"BMI / polyimide","maxC":"260"}]},"basis":"SRC: Hexcel Prepreg Technology table; CompositesWorld for the epoxy tool limit.","sources":["hexcel-prepreg","cw-tooling"],"tags":["matrix","service-temperature","bmi","phenolic"]},{"id":"ply-thickness-formula","kind":"rule","tier":2,"title":"Cured ply thickness and model thickness","summary":"Cured ply t = FAW / (Vf x rho_fibre). 134 gsm at 57.7% on 1.77 g/cm3 fibre gives 0.131 mm; 285 gsm at 50.3% on 1.79 gives 0.316 mm. Model a stack as ply count x this t, not nominal, or bag-side position drifts: 40 plies at 0.13 versus 0.14 mm is 0.4 mm.","applies":[],"value":{"typical":0.131,"unit":"mm"},"basis":"SRC: both results match Hexcel 8552 EU and M56 sheets. Formula from Prepreg Technology Appendix I section B. EST: the 40 ply arithmetic.","sources":["hexcel-8552-eu","hexcel-m56","hexcel-prepreg"],"tags":["ply-thickness","cpt","vf","stack"]},{"id":"process-choice-note","kind":"note","tier":3,"title":"Choosing a process by geometry","summary":"Constant section: pultrude. Revolved: wind. Closed hollow: trapped rubber or RTM. Both faces controlled, small and many: RTM or compression. Long low-curvature skins: ATL. Complex, low count: hand layup. Clips and brackets at rate: thermoplastic stamping.","applies":[],"basis":"EST: synthesis of the process entries in this pack; not from a single source.","sources":[],"tags":["selection","process"]},{"id":"recipe-open-hole-coupon","kind":"recipe","tier":2,"title":"Recipe: D5766 open-hole tension coupon","summary":"A 250 x 36 x 2.5 mm QI coupon with a 6 mm centre hole at the baseline w/D of 6, which fixes the panel and the test fixture for an open-hole allowable.","applies":["coupon"],"basis":"SRC: width and hole from cw-bolted. EST: 250 mm length and 2.5 mm thickness follow D3039 practice and are not confirmed in an opened source.","sources":["cw-bolted","astm-composites"],"tags":["recipe","d5766","coupon"],"recipe":{"prompt":"Model an open-hole tension coupon 36 mm wide with a 6 mm hole","steps":[{"tool":"cad_extrude_profile","args":{"depth":2.5,"outer":[[-125,-18],[125,-18],[125,18],[-125,18]],"holes":[{"circle":{"cx":0,"cy":0,"r":3}}]},"note":"250 x 36 mm x 2.5 mm, w/D 6"}],"expect":{"volume":22429.31,"faceCount":8,"watertight":true,"note":"measured 2026-11-04: first pin"}}},{"id":"recipe-ply-drop-taper","kind":"recipe","tier":2,"title":"Recipe: tapered laminate from 16 to 8 plies at 20:1","summary":"Laminate envelope going from 16 plies to 8 of 0.183 mm tape, 3.66 mm of run per ply on each face, so the model carries the real ramp length from the ply-drop-taper rule. Symmetric about the mid-plane.","applies":["skin","spar cap"],"basis":"EST: worked example of ply-drop-taper and ply-drop-stagger with NCAMP ply thickness. One ply per face per station.","sources":["ncamp-im7-8552","obata-2021"],"tags":["recipe","ply-drop","taper"],"recipe":{"prompt":"Model a laminate strip tapering from 16 to 8 plies of 0.183 mm tape at a 20:1 ramp, 30 mm wide","steps":[{"tool":"cad_extrude_profile","args":{"depth":30,"outer":[[0,-1.464],[20,-1.464],[34.64,-0.732],[54.64,-0.732],[54.64,0.732],[34.64,0.732],[20,1.464],[0,1.464]]},"note":"16 plies 2.928 mm to 8 plies 1.464 mm; 4 plies leave each face over 14.64 mm, 1:20 per face"}],"expect":{"volume":3599.68,"faceCount":10,"watertight":true,"note":"measured 2026-11-04: first pin"}}},{"id":"recipe-core-ramp-blank","kind":"recipe","tier":2,"title":"Recipe: machined core blank with 30 degree edge ramps","summary":"A 300 x 150 mm foam or honeycomb core 10 mm thick with 30 deg ramps along both long edges, each running 17.32 mm, so skins can come together onto a monolithic edge band for fastening.","applies":["sandwich panel","core"],"basis":"EST: worked example of core-edge-ramp (EST angle); 10 mm / tan 30 deg = 17.32 mm.","sources":["hexcel-hsd"],"tags":["recipe","core","ramp"],"recipe":{"prompt":"Model a 300 x 150 x 10 mm core blank with 30 degree ramps on both long edges","steps":[{"tool":"cad_extrude_profile","args":{"depth":300,"outer":[[0,0],[150,0],[132.68,10],[17.32,10]]},"note":"ramps on the 150 mm width, base on the lower skin"}],"expect":{"volume":398040,"faceCount":6,"watertight":true,"note":"measured 2026-11-04: first pin"}}},{"id":"recipe-bolted-lug","kind":"recipe","tier":2,"title":"Recipe: laminate lug at e/D 3, w/D 6","summary":"A 4 mm QI laminate lug for an 8 mm bolt: 48 mm wide, 24 mm hole-to-end and a 40 mm tail, sized by bolted-joint-geometry so it can be compared to a coupon baseline without a width correction.","applies":["lug","bolted flange"],"basis":"EST: e/D 3 per bolted-joint-geometry; w/D 6 SRC coupon baseline. Bolt size and thickness are illustrative.","sources":["cw-bolted"],"tags":["recipe","lug","bolted"],"recipe":{"prompt":"Model a 4 mm laminate lug for an 8 mm bolt at e/D 3 and w/D 6","steps":[{"tool":"cad_extrude_profile","args":{"depth":4,"outer":[[-24,-40],[24,-40],[24,24],[-24,24]],"holes":[{"circle":{"cx":0,"cy":0,"r":4}}]},"note":"w = 48 (6D), hole centre 24 mm from the loaded end (3D)"}],"expect":{"volume":12086.94,"faceCount":8,"watertight":true,"note":"measured 2026-11-04: first pin"}}}]}