Study of automotive side sill/rocker by using carbon fibre reinforced polymer tubes

Abstract

ABSTRACTVehicle side crash is a critical crash event where the vehicle is crashed by a movable car or vehicle may hit a tree or pole. Minimising the intrusion into the occupant space is important to protect the occupant. In side pole crash, vehicle rocker (sill) plays an important role in resisting the load due to the crash. The objective is to study the functional performance and potential mass reduction in the vehicle sill/rocker area by use of carbon fibre reinforced polymer (CFRP) tubes. The study is divided into three parts. First part investigates the behaviour of CFRP square section tubes in a three-point quasi-static bending in comparison to conventional steel structure using finite element method. By keeping the resistance force offered by a steel section as the baseline resistance value, different combination of CFRP tubes and metal holding brackets are evaluated and compared with the baseline. In the second part, CFRP tube is simulated in dynamic three-point bending test and compared with quasi-static simulations in order to check the influence of inertial effects on the CFRP tube behaviour. In the third part, the best performing design variants from the three-point quasi-static bending simulations are used in the sill or rocker of a vehicle and evaluated in full vehicle US NCAP pole impact load case. The full vehicle crash simulations for side pole impact is compared between the baseline with the steel reinforcement and design variants with the CFRP tube. Resistance force levels, intrusion and structural integrity are the key parameters on which this comparison is made. It is concluded that using CFRP tubes does not reduce the performance in terms of structural integrity and intrusion levels in typical side crash scenario like a US NCAP side pole impact. It can also be concluded that there is potential for mass reduction. Further investigation into the assembly feasibility is suggested as future work.