Investigation of creep phenomenon on composite material for bolt connections

One of the main targets in automotive design is weight reduction. This reduction leads to the reduction of gas emissions. Designers tend to use innovative materials in the automotive field such as plastics and composites. To use the right material for the right application, multi material solutions are increasingly adopted. To join dissimilar materials, solutions like adhesive, bolt and nuts, and riveting are necessary. It is necessary to know the behaviour of the materials to be joined, under different loading conditions to ensure the joint. In this work, a bolt connection between composite and aluminium plates has been considered. The behaviour of a carbon fibre reinforced material under compression load, taking into account creep is studied. A specific experimental equipment has been designed and built. A series of experimental compressive tests, in the laminate thickness direction, have been done on carbon fibre reinforced material specimens. Different set-ups in terms of temperature, compression load and surface roughness have been investigated. The obtained results are presented and discussed. A mathematical model will be proposed for interpolation of the obtained results. Finally, a possible strategy for reducing the tightness loss in the initial phase of the joint life is proposed.