Free Vibration Analysis of a Car Bonnet for Damage Detection

A car bonnet or engine hood is identified as one of the automotive closures that provide aesthetic and aerodynamic shape to enhance vehicle performance along with pedestrian's as well as incumbent's safety. Its design is influenced by many parameters such as cost, weight, durability and stiffness to fulfill the requirements of various legislative authorities concerned. Being an integrated structure it is required to monitor the bonnet condition. This paper has defined separation of adhesive joints between inner and outer panels as damage in the bonnet structure. An experimental vibration analysis has been presented for the damage identification of a commercial car bonnet. To verify the results of experimental vibration analysis a parametric model has generated using 3D scanning of an actual bonnet. The natural frequencies for intact and damaged conditions of bonnet have evaluated using finite element analysis (FEA). A classical thin plate theory (CTPT) with justified approximations has also shown applicable to the bonnet assembly to obtain its natural frequencies and identification of the damage occurrence. A well agreement in the results has showed the worthiness of the method.