An improved spring method for calculating the load distribution in multi-bolt composite joints

Fast and reliable prediction of the load distribution is necessary in the initial design of the composite bolted joint structures. Traditional spring method is time consuming in the modelling of a composite bolted joint structure. In this paper, an improved spring method considering the hole clearance and friction effects is developed for efficient modelling of the composite bolted joint structures. This method is based on spring method and finite element theory. A seven-bolt double-lap joint model is built as an example to study the effects of plate width, plate thickness, bolt pitch and clearances on the load distribution. The improved spring method is also adopted in the Monte Caro simulation with clearances considered as uncertain-but-bounded parameters. The results show that the proposed method is time efficient for the load distribution prediction of the bolted joint composite structures.