Thermo-mechanical delamination analysis by a plate model with “adaptive” representation of displacements and temperature

Progressive delamination under thermo-mechanical loading can lead either to a premature failure or a consistent loss of strength and stiffness of laminated and sandwich composites in service. Customary, three-dimensional finite element models are used to predict the stress fields with the highest accuracy, yet the behavior of the delamination crack is simulated by fracture mechanics or cohesive interface models, but these models may overwhelm the computational capacity. Refined plate models that accurately capture the stress fields with a lower computational effort are to date available, which may overcome the problem. Here a recently developed multilayered zig-zag model is applied to the analysis of delamination under impact and thermal loading. This model, which a priori fulfills the equilibrium of out-of-plane stresses and the heat conduction equation at the interfaces, has a hierarchic representation of displacements and temperature across the thickness, but just five displacement d.o.f. and two temperature d.o.f., in order to limit the memory storage occupation. The onset of delamination is predicted using stress based criteria, as customary, while a mesoscale model is used to accurately and efficiently accounts for the evolving damage. So, instead of guessing suited multiplication factors, the degraded properties of the failed regions are computed at each time step. The strain energy updating technique by the author is used to develop an efficient C finite element model. The numerical results show the good accuracy of the present modelling approach.