A crack tip tracking algorithm for cohesive interface element analysis of fatigue delamination propagation in composite materials

摘要: A novel approach is proposed for the use of cohesive elements in analysis delamination propagation composite materials under high-cycle fatigue loading. The method applicable to within Paris-law regime and suitable three-dimensional structures typical aerospace applications. major advantages formulation are its complete independence zone length – which a geometry-dependent parameter relative insensitivity mesh refinement. This only possible via introduction three nonlocal algorithms, provide (i) automated tracking fronts, (ii) an estimation direction crack (iii) accurate mesh-insensitive integration strain energy release rate. All calculations updated at every increment explicit time-integration finite element solution, models envelopes forces displacements with assumption underlying constant cyclic was implemented as user-defined subroutine commercial software LS-Dyna supports complex models. Results presented benchmark cases such specimens central cut plies centrally-loaded circular plates. Accurate predictions growth rates observed different topologies agreement Paris-laws material.