Abstract
Cohesive zone modelling is the main tool to solve the problems of crack initiation and growth, and therefore several mixed-mode cohesive laws are being developed. The majority of the cohesive laws are path independent because this property offers several advantages. However, there has been no experimental evidence of path-independent fracture. Within linear elastic fracture mechanics, path independence is a prerequisite, but not in problems with a large fracture process zone. In this study, it was demonstrated experimentally that path independence applies, to a certain degree, to unidirectional composites with large-scale fibre bridging. Thus, path-independent mixed-mode cohesive laws, preferably derived from a potential function, can be used to describe fracture for this class of materials.
Highlights
The concept of describing fracture by a traction–separation law or a cohesive law was first introduced by [1] and [2]
These nonproportional-loading steady-state fracture resistance values are compared with the steady-state fracture resistance of Double cantilever beam (DCB) specimens continuously loaded up to steady-state fracture, which are plotted as square symbols
It is clear that both sets of DCB experiments, proportional and nonproportional loading, yield the same steady-state fracture resistance within experimental tolerance
Summary
The concept of describing fracture by a traction–separation law or a cohesive law was first introduced by [1] and [2]. Needleman [4] and Xu and Needleman [5] extended the concept of cohesive laws to account for mixed-mode fracture, where the fracture process zone is subjected to normal and tangential separations. For path-independent mixed-mode cohesive laws, the work of the cohesive traction depends only on the normal and tangential separations and not on the opening history, as schematically shown in Fig. 1a and in Fig. 1b with solid lines. For mixed-mode cohesive laws, which are path dependent [8,18,19], the mixed-mode fracture energy depends on the loading history, as shown in Fig. 1b with dashed lines. A mixed-mode cohesive law is path dependent if it cannot be derived from a potential function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
