Input Loading for Squeak & Rattle CAE Analysis

A method to create a CAE load by utilizing the vibration motions at structure attachments has been developed. This method employs the concept of enforced motion as the constraints of boundary conditions to create an equivalent input force/moment matrix for a sub-structure with multi-point attachments. The main assumption is that motions at the attachments of the sub-structure should be the same as the known motions of the main structure under the generated input load. The key concept of the developed methodology is the calculation of the input dynamic compliance matrix for sub-structure attachment locations. This method is developed to create a system level input load to be used for squeak and rattle CAE analysis on a component or sub-system. It can also be used for minor component design change evaluation using only the component CAE model, yet as if it is assembled in the vehicle. It also enables the creation of CAE system level loads for non-structural trimmed body components such as the door trim panel and the floor console which are not included in a typical trimmed body CAE model. Two example cases are provided to show the usage and accuracy of the methods. The first example is a simple rectangular plate to serve as a benchmarking problem. The second one is an instrument panel on a typical sedan.