Architecture of a multi-crack model with full closing, reopening and sliding capabilities

This paper discusses the finite element modeling of cracking of quasi-brittle materials under cyclic loading. A damage based crack model is proposed, which considers tensile and compressive damage, irreversible strains upon unloading in compression, as well as micro-crack closure-reopening effects with special attention to the sliding of open cracks (MCRS). The model is implemented in conjunction with a mixed strain/displacement finite element formulation which provides enhanced accuracy and guarantees mesh size and bias independent results. Two distinct damage models are developed. The first one is based on the classical fixed orthotropic crack models and the second is an isotropic version. Both of them incorporate the necessary elements to furnish full MCRS capabilities. The model is demonstrated through several examples of application and comparison with experimental evidence, in mode I, mode II and mixed mode monotonic and cyclic loading.