A mixed-mode fatigue crack growth model for co-consolidated thermoplastic joints

Modelling of Fatigue Delamination Growth and Prediction of Residual Tensile Strength of Thermoplastic Coupons

“…The adopted modeling approach is based on the work of Tserpes et al [24]. It combines a quasi-static progressive damage model (PDM) [25,26], the cohesive zone modeling (CZM) method, and a fatigue interfacial crack growth model [18]. The PDM is used to simulate intralaminar damage and the CZM method together with the fatigue crack growth model to simulate fatigue delamination.…”

“…To simulate fatigue delamination growth, a recently developed fatigue crack growth model for co-consolidated thermoplastics [18] was used. The model relies on a modified Paris' law, which is used for the calculation of fatigue crack growth rate da/dN in form of…”

“…where d tot is the total damage variable (0: undamaged, 1: failed), while d s and d f are the static and fatigue contributing damage variables, respectively. The stress state σ for each element in the fatigue activated zone has been degraded using σ = (1 − d tot )σ max (18) where σ max is the maximum traction of the affected element.…”

“…The fatigue crack growth model has been fully validated upon the same experimental parameters (stress ratio, max. load percentage) for the same interfaces in [18].…”

“…Three LS-DYNA FE models (standard, continuum damage mechanics (CDM), and discrete) were developed, all using cohesive interface elements for delamination. Recently, Sioutis and Tserpes [18] have developed a fatigue interfacial crack growth model based on the cohesive zone modeling method, which has been proven capable of efficiently simulating the fatigue interfacial fracture of co-consolidated thermoplastic joints. Provided the co-consolidated interfaces have the same mechanical performance as the ply interfaces, the model of Sioutis et al [18] could be used for simulating fatigue delamination of thermoplastic coupons.…”