Numerical aspects of cohesive-zone models

The importance of the cohesive-zone approach to analyse localisation and failure in engineering materials is emphasised and various ways to incorporate the cohesive-zone methodology in computational methods are discussed. Numerical representations of cohesive-zone models suffer from a certain mesh bias. For discrete representations this is caused by the initial mesh design, while for smeared representations it is rooted in the ill-posedness of the rate boundary value problem that arises upon the introduction of decohesion. A proper representation of the discrete character of cohesive-zone formulations which avoids any mesh bias can be obtained elegantly when exploiting the partition-of-unity property of finite element shape functions. The effectiveness of this approach is demonstrated by some examples.