Prediction of Internal Responses Due to Changes in Boundary Conditions Using System Frequency Response Functions

Vibration testing is often carried out for automotive components to meet guidelines based on their operational environments. This is an iterative process wherein design changes may need to be made depending on an intermediate model’s dynamic behavior. Predicting the behavior based on modifications in boundary conditions of a well-defined numerical model imparts practical insights to the component’s responses. To this end, application of a general method using experimental free-free condition frequency response functions of a structure is discussed in the presented work. The procedure is shown to be useful for prediction of responses when kinematic boundary conditions are applied, without the need for an actual measurement. This approach is outlined in the paper and is applied to datasets where dynamic modifications are made at multiple boundary nodes. Experimentally measured frequency response functions are used to define the dynamic behavior of a real automotive component and used for prediction of responses under measured kinematics of the boundary nodes. Verification is carried out through the application of a controlled vibration environment on a shaker, where the responses are measured and compared against the predicted ones. The results indicate the efficacy of the presented concept. It is advantageous when certain locations, such as degrees-of-freedom internal to the structure, may not be explicitly measurable in the field but are important for product development.