Simulating the effect of fiber bridging and asymmetry on the fracture behavior of adhesively-bonded composite joints

The fracture behavior of adhesively-bonded pultruded double cantilever beam specimens is studied in this chapter. The crack propagates along paths away from the symmetry plane and is accompanied by fiber bridging. Finite element models are developed to quantify the effects of asymmetry and fiber bridging on the fracture energy. The virtual crack closure technique can be used for calculation of the fracture components at the crack tip and an exponential traction–separation cohesive law can be applied to simulate the fiber-bridging zone. The cohesive zone model developed in this chapter can be used for simulating progressive crack propagation in other joint configurations composed of the same adherends and adhesive

Creep/fatigue/relaxation of angle-ply GFRP composite laminates

Fiber-reinforced polymer (FRP) composites are used in engineering structures of several domains, such as wind energy, bridges, and automotive industry. Usually such material systems include polymeric matrices and exhibit behavior that is sensitive to the loading pattern due to their cyclic- and time-dependent mechanical properties. Although the majority of the aforementioned engineering applications undergoes a significant number of fatigue cycles, of random loading profiles, throughout their lifetime, the research efforts assigned to the investigation of the loading effects on their fatigue behavior are still very limited. Fatigue design allowables are today derived from standardized experimental investigations, mainly subjecting the examined materials under constant amplitude continuous fatigue loading; not corresponding to actual loading profiles seen by the structures in open air applications. This chapter aims to present the effect of different loading patterns on the fatigue life and damage development of angle-ply thermoset composites, discussing the influence of load interruptions including periods of zero load, when the material recovers, or periods of load hold times, during which the material creeps