Simulation driven design of timber bolster in fibre composite

Sammanfattning: The primary objective of this thesis is to investigate a simulation and optimisation based methodology using fibre composite materials to lower the weight of timber bolsters. The timber bolsters secure the timber from falling off the truck during loading and transport. A lighter forestry truck is beneficial for several reasons such as increased payload and fuel efficiency and a decreased environmental impact. This thesis includes a concept study for a bolster made of fibre composites. Carbon and glass fibres together with polyurethane were chosen as material system and the recommended manufacturing methods were pultrusion and resin transfer moulding. A study of the economy related to the timber transport was conducted during the concept phase to investigate the potential business case. The thesis also includes an optimisation of the generated concept. The optimisation focused on geometry and fibre layup. By the use of optimisation the weight was reduced from the initial 136 kg of aluminium to 87 kg of glass and carbon fibre. The optimised design was compared with today’s aluminium bolsters and indicated that the composite bolster is realistic from an economic perspective. A methodology for analysing bolted joints in fibre composites was developed. The analysis was made using the finite element method and resulted in a comparison between different failure criteria. Based on the results it can be concluded that the prediction of failure differs significantly depending on used failure criterion and tests are needed for verification. Finally a simulation was made to verify the structures response to an impact. The simulation was compared with calculations using energy equations showing a fairly good agreement.