A Hemivariational Inequality and a Nonconvex Energy Bundle Approach to the Problem of Debonding in Adhesively Bonded Composite Structures
In the present paper the problem of debonding in adhesively bonded composite structures is examined. The main reason that leads to the damage of these structures is the delamination effect due to the considered external loading. The adhesive material is assumed to obey to a nonmonotone, possibly multivalued three-dimensional stress-strain law. This kind of behaviour results in a nonconvex nonsmooth energy function in the problem introducing a hemivariational inequality that is the expression of the principle of virtual work in inequality form. This problem is equivalent to a substationarity problem of the minimum of potential energy of the structure that is an optimization problem. The application of the optimization programme NSOLIB, based on the proximal bundle method, converges to one at least substationarity point which is a solution of the problem at hand. In the last part of the paper the study of a steel frame and a composite two-layered structure demonstrates the effectiveness of the proposed method.
KeywordsEpoxy Brittle Flange Summing
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