Vehicle hood experiences impact loading once it is dropped freely from a specific height. This phenomenon is known as Hood Slam (HS). HS induces damage to the components of the hood and front end module. This damage accumulates over the vehicle lifetime and may lead to failure. In a traditional design process, the durability performance of the hood and front end module is evaluated by conducting an impact test. It is, however, very costly and time-consuming to achieve a statistical-based confidence. This paper presents the CAE methodology that intends to replace the physical test and predict the durability performance of the hood and front end module early in the design cycle.
The precise capturing of the time dependent contact conditions between the different components of the closing mechanism is essential in simulating the load transfer between the hood and the body. The body-hood contact sequence brings about a variable deformation of the bump stops, due to the curbed movement of the hood and the resulting modal oscillations of the hood itself.
This CAE method demonstrate simplistic modeling of latch to capture precisely all the phases in hood slam event. Predefined initial rotational velocity is applied on the hood and the dynamic response of the structure is studied over a period of time. The impact loading causes local deformation and stress concentration, which may become potential failure spots. The stress time history from the impact simulation is used to evaluate the fatigue life of the component. FEA results are correlated with the physical test results. This paper explains the benefit of CAE technology to the vehicle closures development.
