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Rate-Dependent Cohesive Zone Modeling of Unstable Crack Growth in an Epoxy Adhesive

2009; Taylor & Francis; Volume: 16; Issue: 1 Linguagem: Inglês

10.1080/15376490802540556

1537-6532

Dhaval P. Makhecha, Rakesh K. Kapania, Eric R. Johnson, David Dillard, George Jacob, J. Michael Starbuck,

Material Properties and Processing

Abstract This paper presents the development and numerical implementation of a rate-dependent fracture model of an epoxy adhesive. Previous mode I fracture tests conducted under quasi-static, displacement controlled loading of an aluminum double cantilever beam (DCB) bonded with the epoxy exhibited unstable crack growth in the adhesive. Results from mode I fracture tests of compact tension specimens made from bulk adhesive at increasing cross head opening speeds are reported in this paper. The compact tension tests results showed a decreasing critical strain energy release rate with increasing cross head speed, with the critical energy release rate at 1 m/s cross head speed equal to about 20% of its quasi-static value. Two rate-dependent cohesive zone models are formulated based on the compact tension test data. A cohesive de-cohesive relationship was postulated between the tractions acting across the crack faces and the opening displacement and opening velocity. These rate-dependent cohesive zone models are implemented in an interface finite element to model discrete crack growth in the adhesive. The reaction force history from simulation of the DCB test is in good agreement with the test data using only the rate-dependent interface element to model the adhesive. Keywords: cohesive zone modelingrate-dependent epoxy behaviorunstable crack growth ACKNOWLEDGMENT The authors would like to thank the project monitor Dr. Naveen Rastogi for technical discussions held with him. We also acknowledge that this research is supported, in whole or in part, by the Automotive Composite Consortium's Department of Energy Cooperative Agreement No. DE-FC05-95OR22363. Such support does not constitute an endorsement by the Department of Energy of the views expressed herein. Presented at the 2005 ASME International Mechanical Engineering Congress and Exposition, Orlando, Florida