Review of natural joints and bio- inspired CFRP to steel joints

Abstract

There is a great variety of joint types used in nature, from jaws, bones and tendons to root systems and tree branches. To understand how to optimise biomimetic-inspired engineering joints, fi rst it is important to understand how biological joints work. In this paper, a review based on the functions of natural joint systems is presented. Emphasis was given to understanding natural joints from a mechanical point of view, so as to inspire engineers to fi nd innovative methods of joining man-made structures. Nature has found many ingenious ways of joining dissimilar materials, with a transitional zone of stiffness at the insertion site commonly used. In engineering joints, one way to reduce the material stiffness mismatch is to gradually decrease the effective stiffness of the steel part of the joint by perforating it with holes. This paper investigates joining of fl at perforated steel plates to a CFRP part by a co-infusion resin transfer moulding process. The joints are tested under static tensile loading. The perforated steel joints show a 175 % increase of joint strength comparing to non- perforated ones. Finite element analyses are used to interpret the experimental results.