Modelling the behaviour of bolted composite material connections

This thesis proposes a model to predict the through-thickness behaviour of bolted fibre reinforced composite joints. Although work has been done to predict the stress distributions in thin composite plates that are loaded by a transverse pin, these models do not take into account the contribution of the fastener behaviour on the joint performance. Fastener flexibility, rotational restraint of the fastener ends, axial forces in the fastener, and interface characteristics between the joint members will all affect the strength and stiffness of the joint.The proposed model combines the results of two planar analyses. The first analysis, which models a non-rigid pin loaded plate, analyzes the pin-plate contact problem and determines the relationship between the load on the pin and the embedment of the pin into the plate. The plate represents a single lamina, composed of unidirectional fibres that are held together in a matrix material and are defined by a unique load to fibre angle. A finite element computer code was developed to solve contact problem. Confidence was gained on the computer code by solving standard test problems. The second analysis models the non-rigid bolted assembly made up of a bolt, passing through two or more composite members, loaded in single or double shear. The bolt is modelled as a beam on an inelastic, nonlinear foundation, where the properties of the foundation, obtained from the first analysis, change through the thickness of the member corresponding to the load-embedment relationship for each lamina crossed by the bolt. An existing computer program was used for the second part of the analysis. The strength and stiffness of a composite material joint was evaluated by using the two-part model to show the applicability of the proposed model.