An overview of Carbon Fiber modeling in LS-DYNA John Zhao zhao@lstc.com October 23 th 2017
Outline Manufacturing of Carbon Fiber Compression molding *MAT_277 & 278 *MAT_293 *MAT_249 Resin transform molding Short chopped fiber Crash application of Carbon Fiber Continuous fiber *MAT_054 & 058 *MAT_261 & 262 Short chopped fiber *MAT_157 Continuous fiber reinforced polymers (glass/carbon/pa/pp/ep) Short-/long fiber reinforced polymers (glass/pp)
Collaboration *MAT_ADHESIVE_CURING_VISCOELASTIC (277) DOW chemical FORD *MAT_COMPRF (293) FORD Northwestern university *MAT_REINFORCED_THERMOPLASTIC (249) BMW *MAT_LAMINATED_FRACRURE_DAIMER_PINHO (261) *MAT_LAMINATED_FRACTURE_DAIMER_CAMANHO (262) Mercedes *MAT_ANISOTROPIC_ELASTIC_PLASTIC with IHIS for short fiber OPEL
Compression molding of thermoplastic pre-preg heating positioning forming cooling final part Epoxy resin curing is modeled by *MAT_277 (Dow chemical) Woven fabric part can be modeled by *MAT_234 & 235
*MAT_ADHESIVE_CURING_VISCOELASTIC (277) Curing Kinetics dα dt = (K 1 + K 2 α m )(1 α) n K 1 = k 1 exp c 1 RT, K 2 = k 2 exp c 2 RT Thermal Expansion Chemical Shrinkage Stress Relaxation T ε th ij = β(α, T)δ ij dt T 0 β α, T = 1 α β 0 T + αβ 1 T α ε ch ij = γ(α, T)δ ij dα 0 γ α = Aα 2 + Bα + C G t = G + G i exp ( β G i t) i=1 log α H = C 1 (T T ref ) (C 2 + T T ref ) N
*MAT_ADHESIVE_CURING_VISCOELASTIC Single element test case Initial curing degree set to be 0 Applied temperature boundary condition Applied displacement boundary condition Simulate complete compression molding process
*MAT_ADHESIVE_CURING_VISCOELASTIC
*MAT_ADHESIVE_CURING_VISCOELASTIC
*MAT_ADHESIVE_CURING_VISCOELASTIC σ xx history plot
*MAT_MICROMECHANICS for continuous woven pre-preg Consists both loose fabric and epoxy resin Models fiber reorientation due to mechanical deformation and resin curing Viscoelastic properties of epoxy resin are functions of curing degree 3 2 z 1 y x Representative Volume Cell z sub-celiv warp yarn y sub-celi filyarn sub-celi sub-celi x
*MAT_278 single dome preforming simulation Fiber original orientation 0 /90 vs 45 /-45 Testing Fiber Orientation
*MAT_278 single dome preforming simulation Fiber original orientation 0 /90
*MAT_278 single dome preforming simulation Fiber original orientation 45 /-45
*MAT_293 (Northwestern University, Ford) Stress caused by stretch in fiber directions: Stress caused by fiber-fiber angle change: Combine the two stress: Experiment: uniaxial tension Or RVE: tension stiffness data Experiment: bias-extension Or RVE: shear stiffness data Implement the stresses as functions of fiber stretch and rotation into the user defined material.
*MAT_293 Deformation gradient tensor F Fiber directions and angle Fiber angle < Shear locking angle β lock Yes No Before locking After locking Stress caused by fiber rotation Stress caused by fiber stretch Stiffened shear stress caused by fiber contact Total stress before locking Total stress after locking β lock Bias-extension test specimen. Shear stress evaluation: dσ m XY = dσ m YX = E dε XY E: transverse compression modulus. Non-orthogonal stress calculation is included in the flowchart. After shear locking, the stress calculation algorithm is converted.
*MAT_293 Uniaxial tension tests demonstration 1. Strain (fiber stretch)-stress curve from uniaxial tension tests.
*MAT_293 Bias-extension tests demonstration 1. Shear angle-stress curve from bias-extension tests.
*MAT_293 Bending tests demonstration. Bending shape comparison at 70 ºC for bending stiffness reverse calculation. MAT_COMPRF (MAT_293) input deck.
*MAT_293 Simulation was performed on LS-DYNA with corresponding fiber orientations and boundary conditions. Punch, rigid, Belytschko-Tsay shell, disp=89 mm Binder, rigid, Belytschko-Tsay shell, disp=0.06 mm Composite, MAT_293, 3.8mm X 3.8mm fully integrated shell elements (Material unitcell side length is 9.2 mm) Double-dome simulation setup. Die, rigid, Belytschko-Tsay shell Prepreg-prepreg interaction: static/dynamic friction factor=1.9. Prepreg-tool interaction: static/dynamic friction factor=0.2.
*MAT_293 The prediction capability of the material model is validated on the basis of onedirection draw-in distance and fiber angle distribution. Draw-in validation and comparison experiment Non-ortho Ortho Draw-in / mm 49 42 (85.7%) 73 (149.0%) Angle validation and comparison Location experiment Non-ortho Ortho A 80º 81º (101.3%) 70º (87.5%) B 88º 88º (100.0%) 85º (96.6%) C 71º 73º (102.8%) 86º (121.1%) D 49º 46º (93.9%) 47º (95.9%) Single layer double dome simulation and experiment results comparison for draw-in distance and yarn angle validation. E 56º 60º (107.1%) 59º (105.4%) F 66º 70º (106.1%) 77º (116.7%)
*MAT_293 Inter-layer sliding and wrinkling pattern are compared qualitatively for the double layers double dome preforming case. 0/90 o ±45 o Double layers double dome experiment results. Double layers double dome simulation results. Overall geometry and inter-layer sliding are well captured. The discrepancy in the geometry, sliding, and wrinkle location might be caused by the inaccurate temperature and interaction factor.
*MAT_249 for pre-preg
*MAT_249_UDFIBER Option for dry continuous non crimped fabric User material developed by BMW *MAT_249_CRASH Failure/damage of thermoplastics reinforced with WOVEN fabric Based on simplified *MAT_249 A phenomenological model implemented Damage defined by load curves Experiments done by A German university and Brose Material calibration with LS-OPT
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) EA, EB, PRBA, PRCA, PRCB, GAB XC, XT, YC, YT, SC SLIMT1, SLIMC1, SLIMT2, SLIMC2 are stress limits in softening part. SLIMTx starts with 0.3, and SLIMCx starts with 1.0 AOPT is used, if coordinate system is defined for material direction
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: UD
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: woven 0-90
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: Quasi Isotropic
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058)
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058)
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: NCAP
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: offset
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: rigid center pole
Crash Application of Carbon Fiber *MAT_LAMINTATED_COMPOSITE_FABRIC (*MAT_058) Load vs displacement: low speed quarter
Crash Application of Carbon Fiber *MAT_LAMINATED_FRACTURE_DAIMER_PINHO (*MAT_261) Coupled failure criterion based on 3d stress state Complex 3d fiber kinking model Matrix failure invokes search for controlling facture plane Linear softening law based on facture toughness 1d plasticity model for in plane shear behavior defined by load curve * MAT_LAMINATED_FRACTURE_DAIMER_CAMANHO (*MAT_262) Coupled failure criterion based on 2d stress state Constant fiber misalignment angle based on shear and longitudinal compressive strength Matrix failure fixed planes Bi-Linear softening law based on facture toughness 1d plasticity model for in plane shear behavior defined by load curve
Crash Application of Carbon Fiber *MAT_LAMINATED_FRACTURE_DAIMER_PINHO (*MAT_261)
Crash Application of Carbon Fiber *MAT_LAMINATED_FRACTURE_DAIMER_CAMANHO (*MAT_262)
Short fiber *MAT_157 with *INITIAL_STRESS *MAT_147 is anisotropic elastic platic material with C 6x6 matrix input With AOPT=0, initialize orientation and stiffness matrix with *INITIAL_ STRESS_SHELL card Data mapping between Moldflow/Moldex3d to *INITIAL_STRESS card Fiber orientation and probability information, q1 q2 Fiber and matrix elastic properties
The End!