Fatigue and fracture

Fiber-reinforced polymer (FRP) structures, such as bridges, are light in weight compared to their live loads and have a service life of up to 100 years. The sustained repetitive loading to which they are subjected thus raises the question of the fatigue behavior of such structures, and particularly their connections, which in many cases are adhesively bonded. A frequent failure mode in FRP structures is debonding, e.g. in structural joints between adherends or between skins and cores of sandwiches. To understand and describe this fracture behavior, fracture mechanics joints are used to derive mixed-mode failure criteria. However, currently used fracture mechanics joints are not able to simulate two-dimensional crack propagation, e.g. originating from defects in the skin-core interface of sandwiches.