Minimising the Number of Finite Elements Required for Analyses of Adhesively-Bonded Joints

This paper on "Minimising the Number of Finite Elements Required for Analyses of Adhesively-Bonded Joints" was presented at the NAFEMS World Congress on Effective Engineering Analysis - 25-28 April 1999, Newport, Rhode Island, USA.

Summary

This paper reports on significant progress made towards the finite-element prediction of the stress distribution and strength of an adhesively-bonded joint using a minimum number of elements. In a conventional analysis of this type, substantial mesh refinement, perhaps involving hundreds of elements, would be required to model accurately the interfacial stress singularities that are known to exist at the ends of the bond line. However, the ultimate aim of this research is to be able to model the adhesive layer and overlap sections of the adherends in the single-lap joint each using as few Lagrangian-type isoparametric elements as possible. Through selective re-positioning of mid-side nodes the predicted distribution of stress accounts for the interfacial singularities. For joints with a complex geometry more of these elements would be required but this number would still be minimal in comparison to the conventional approach. Example finite element analyses were performed to assess the accuracy of the new elements in terms of both the predicted distribution of strain and the joint strength for comparison with results obtained elsewhere. The outcome was favourable and this could form the basis for the development of a more generalised bonded joint theory.