Vol4 num2-15 Failure prediction in the neighbourhood of the hole in riveted joints with composite materials

Abstract

In riveted joints, typically two groups of failure mechanisms must be verified, those that affect the joining elements and those that affect the parts that must be drilled to be joined. In this last group, at least, three failure mechanisms must be taken into account: tension, shear and bearing. In each of these failure mechanisms, it must be verified that the component of the stress state responsible for the failure does not exceed a certain critical value that causes the failure. In the case of riveted joints with composite materials, the task is doubly complex. On the one hand, the stress state in the neighbourhood of the hole is complex, not only because of the non-linearity of the problem (the contact of the rivet with the walls of the hole) but also because of the non-isotropic nature of the material. This makes the stresses to have a strong dependence on the type of fiber, stacking sequence, and in general, on the mechanical properties (non-isotropic) of the laminate. On the other hand, the determination of the critical values, associated with each component of the stress state, responsible for each failure mechanism, is difficult to obtain, due to the fact that these strength values also depend on the particular orientation along the hole contour, where they are evaluated. In the present work, the stress state in the neighbourhood of the hole is evaluated in riveted joints with composite materials, analyzing different types of laminates, to serve as a basis for the prediction of the different failure mechanisms potentially acting.