3-D Progressive Failure Analysis of Bonded Composite Joints

Alexander E. Bogdanovich and Sergei P. Yushanov

ABSTRACT

This paper presents novel development of 3-D variational Stress/ Strain and progressive failure analysis of adhesive composite joints. The approach is based on the earlier proposed 3-D Mosaic Model and associated variational principle of minimum total potential energy. The displacement field in a composite structure is approximated in terms of triple series with Bernstein basis of functions used for all three coordinate directions. A progressive failure analysis approach utilizes the strain energy release rate to predict various scenarios of cohesive, adhesive or interlaminar crack propagation. Several cracks of the same type or different types can be considered simultaneously. Numerical example of the double lap adhesive joint of unidirectional composites illustrates the developed analysis approach. First, the computed strains are compared to the experimental strain measurements. Then, the initial failure site and failure mode are identified, and the progressive failure analysis is performed, starting with the initial crack(s) which can be located between the adhesive and adherents, inside the adhesive, or between the layers if the composite adherent. Preliminary numerical results illustrate the applicability of the developed analysis approach for predicting the dominating crack propagation path in double-lap composite bonded joint.