Predicting cleavage fracture in presence of residual stresses; A numerical case study

The extensive use of adhesive bonding has placed significant research interest in development of fracture prediction tools for bi-material interface problems. The focus of the research reported here is to address this issue for a specific adhesive bond problem. This has been achieved through the development of a comprehensive transformative numerical code in ANSYS. Fundamental hypotheses are presented in order to employ relevant singular elements on crack tip. Element type and size effects on results are discussed. The fracture criterion examined for modeling progressive growth of sharp crack in E27/steel interface is based on the maximum principal stress. Recent laboratory findings were used for Mode-I fracture data of CT specimen. Analyses have been implemented by modeling both linear elastic and nonlinear hardening behavior of E27 according to standard tensile test data for this epoxy. The results are discussed in details. Also a simple brittle failure predicting approach, based on near tip linear elastic interfacial fracture mechanics (LEIFM), is demonstrated and proposed to the specific bond problem. Final model affords to elaborate acceptable failure conditions for bi-material bonded structures with interfacial cracks.