Guidelines for the implementation of the CWELD and ACM2 spot weld models in structural dynamics

Of the many spot weld models suggested in the literature, CWELD and ACM2 are the most widely used in industry. They are coarse models with the important characteristic that they allow the welded plates to be meshed independently. This makes them suitable for modelling large spot welded structures such as an automotive body-in-white. Although widely used, no guidelines exist in the literature for their implementation. It is shown in this paper that the natural frequencies of the benchmark structures are very sensitive to some parameters characterising these models. In practice, often little care is exercised in setting the values of these parameters to be close to their optimal values. In this paper the techniques of model updating in structural dynamics are used to analyse and improve CWELD and ACM2 models, and guidelines are given for their optimum implementation.