Accounting for viscoelastic effects in a multiscale fatigue model for the degradation of the dynamic stiffness of short-fiber reinforced thermoplastics

Abstract Under fatigue loading, the stiffness decrease in short-fiber reinforced polymers reflects gradual degradation of material. Thus, both measuring and modeling this is critical to investigate understand entire process. Besides evolving damage, viscoelastic effects within polymer influence measured dynamic stiffness. In paper, we study a linear material model for matrix on obtained extend an elastic multiscale fatigue-damage viscoelasticity. Our contribution two-fold. First, revisit complex-valued models known literature predict asymptotic periodic orbit For small phase shifts isotropic material, show through numerical experiments that real-valued computation “elastic” sufficient approximate microstructure with generalized Maxwell equal Poisson’s ratios every element as matrix, by inclusions. This makes standard solvers applicable fiber-reinforced thermoplastics. Secondly, propose thermoplastic based decoupling time scales where manifest. We demonstrate capability evolution under loading polybutylene terephthalate (PBT) validation experimental results.