An experiment-informed mesoscale finite element framework for predicting the tensile properties of CFRTP-SMC composites

This study establishes an experiment informed mesoscale FE framework capable of explaining the tape-length-dependent tensile behavior of carbon fiber reinforced thermoplastic sheet molding compound (CFRTP-SMC) composites and simulating the progressive damage process governed by multiple failure modes. The orientation distribution and volume fraction of fiber tapes in the numerical model were obtained from the short-time Fourier transform (STFT) based reconstruction of the SMC preform and the ash test, respectively. Each constituent of the mesoscale FE model, including fiber tapes, resin-rich regions, and interfaces, is modeled with its own constitutive law and damage evolution criterion. The simulations successfully reproduce the experimentally observed dependence of tensile stiffness and strength on fiber tape length, with prediction errors below 10 percent for both. Progressive damage analysis reveals that the SMC considered in this study exhibits longitudinal and transverse fiber tape fracture accompanied by tape de-bonding. The final fracture path tends to propagate between transverse fiber tapes, while the extent to which longitudinal tapes participate in the failure process largely governs the macroscopic tensile strength of the specimen. The proposed framework is verified through a comprehensive comparison with experimental results obtained from tensile tests, micro-computed tomography (CT) observations, acoustic emission (AE) test, digital microscopy and scanning electron microscopy (SEM) analyses. • Reconstructed the fiber tape distribution in SMC preforms using a short-time Fourier transform approach. • Developed an experiment-informed mesoscale SMC FE model. • The mesoscale SMC FE model captured the progressive tensile failure process involving multiple failure modes. • Predicted tape-length-dependent tensile stiffness and strength within 10% of experimental measurements.