An evaluation of mode-decomposed energy release rates for arbitrarily shaped delamination fronts using cohesive elements

• Published in: Computer methods in applied mechanics and engineering Vol. 347; pp. 218 - 237
• Main Authors: Carreras, L., Lindgaard, E., Renart, J., Bak, B.L.V., Turon, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-04-2019; Elsevier BV
• Subjects: 3D [formula omitted]-integral; Cohesion; Cohesive zone model; Composite structures; Crack closure; Crack propagation; Decomposition; Delamination growth; Energy release rate; Exact solutions; Finite element analysis; Finite element method; Formulations; Fracture mechanics; J integral; Linear elastic fracture mechanics; Three dimensional composites; Energy release rate; 3D J-integral; Finite element analysis; Cohesive zone model; Delamination growth
• ISSN: 0045-7825; 1879-2138
• DOI: 10.1016/j.cma.2018.12.027

Computing mode-decomposed energy release rates in arbitrarily shaped delaminations involving large fracture process zones has not been previously investigated. The J-integral is a suitable method for calculating this, because its domain-independence can be employed to reduce the integration domain to a cohesive interface, and reduce it to a line integral. However, the existing formulations for the evaluation of the mode-decomposed J-integrals rely on the assumption of negligible fracture process zones. In this work, a method for the computation of the mode-decomposed J-integrals in three-dimensional problems involving large fracture process zones and using the cohesive zone model approach is presented. The formulation is applicable to curved fronts with non-planar crack faces. A growth driving direction criterion, which takes into account the loading state at each point, is used to render the integration paths and to decompose the J-integral into loading modes. This results in curved and non-planar integration paths crossing the cohesive zone. Furthermore, its implementation into the finite element framework is also addressed. The formulation is validated against virtual crack closure technique (VCCT) and linear elastic fracture mechanics (LEFM)-based analytical solutions and the significance and generality of the formulation are demonstrated with crack propagation in a three-dimensional composite structure.
•3D J-integral applicable to problems involving large fracture process zones.•A mode I–II–III decomposed J-integral for large fracture process zones.•Evaluation of the J-integral using the information from the cohesive zone model.•Efficient implementation of the mode-decomposed J-integral using cohesive elements.•Application of the method to a 3D structure under mode I, II and III loading.