Numerical simulation of cold working of rivet holes

The cold working process is a well-known technique used to improve the fatigue life in aircraft structures. It has been shown that the only way to accurately simulate the cold working process using finite elements is modelling the plate, mandrel and sleeve. Usually, two-dimensional, two-dimensional axisymmetrical and three-dimensional models are used to predict the resulting residual stress field. This type of problem requires complex calculations and is time consuming since it involves the use of contact between the elements assembled and non-linear geometric and material models to simulate the behaviour of the plate. In engineering problems, simpler analyses are preferable as long as the errors caused by the simplifications can be quantified. This paper presents and compares the results obtained using models with different levels of complexity. The consequences of using some of the normal approximations concerning to the geometry, boundary conditions and type of model used, are evaluated.