A study of intra-laminar damage in double-lap, multi-bolt, composite joints with variable clearance using continuum damage mechanics

A damage modelling approach, based on a continuum damage model (CDM) formulation, is proposed and applied to the problem of double-lap, multi-bolt, fibre-reinforced composite joints with variable clearances, subjected to quasi-static tensile loading. A new method of dealing with fibre failure is included in the CDM model, which is implemented in a commercial implicit finite element analysis code. The model is validated at element and structural levels by comparing with experimental data. It has been found that, for the joints examined in this paper, our formulation is capable of modelling development of damage from bearing failure onset all the way to ultimate catastrophic net-tension failure without numerical problems, which is an advance over previous work. The predictions from the CDM model of net-tension failure modes and ultimate loads are in good agreement with those from the experiments. Furthermore the model is capable of explaining some non-intuitive experimental findings, such as the larger energy absorption obtained in joints with higher clearances.