No abstract

This paper focuses on the effect of fiber orientation and stacking sequence on the progressive mixed mode delamination failure in composite laminates using fracture experiments and finite element (FE) simulations. Every laminate is modelled numerically combining damageable layers with defined fiber orientations and cohesive zone interface elements, subjected to mixed mode bending. The numerical simulations are then calibrated and validated through experiments, conducted following standardized mixed mode delamination tests. The numerical model is able to successfully capture the experimentally observed effects of fiber angle orientations and variable stacking sequences on the global load-displacement response and mixed mode inter-laminar fracture toughness of the various laminates. For better understanding of the failure mechanism, fracture surfaces of laminates with different stacking sequences are also studied using scanning electron microscopy (SEM).

This paper analyses the progressive mixed mode delamination failure in unidirectional and multidirectional composite laminates using fracture experiments, finite element (FE) simulations and an analytical solution. The numerical model of the laminate is described as an assembly of damageable layers and bilinear interface elements subjected to mixed mode bending. The analytical approach is used to estimate the total mixed mode and decomposed fracture energies for laminates with different stacking sequences, which is also validated through experiments. It is concluded that the interlaminar fracture toughness of multidirectional laminates is considerably higher than that of the unidirectional ones. The effect of initial interfacial stiffness and element size is studied and it is also shown that their value must not exceed a definite limit for the numerical simulations to converge. The model can also be further extended to simulate the mixed mode fracture in hybrid fiber metal laminates.

No abstract

Titanium matrix composites (TMCs) have been developed as high performance materials for light weight structural applications. The materials are comprised of a silicon carbide (SiC) fiber embedded in a titanium matrix, thus making use of the high strength of the SiC fibers, their high stiffness and creep resistance at elevated temperatures combined with the damage tolerance of titanium alloys. Since materials properties are closely related to the quality of the fabrication process, TMC processing is of major importance. Moreover, reinforcement‐induced anisotropy of the material and thermal residual stresses formed during the consolidation process must be considered and understood for proper component design. Finally, modeling using FE methods reduces the time needed for component development and helps to elucidate failure mechanisms of the material.