An Investigation of Body Inertance Response for Occupant Safety Control Module Attachment Regions

Current generation passenger vehicles are built with several electronic sensors and modules which are required for the functioning of passive safety systems. These sensors and modules are mounted on the vehicle body at locations chosen to meet safety functionality requirements. They are mounted on pillars or even directly on panels based on specific packaging requirements. The body panel or pillar poses local structural resonances and its dynamic behavior can directly affect the functioning of these sensors and modules. Hence a specific inertance performance level at the mounting locations is required for the proper functioning of those sensors and modules. Drive point modal frequency response function (FRF) analysis, at full vehicle model for the frequency range up to 1000 Hz, is performed using finite element method (FEM) and verified against the target level along with test correlation. The arrival of acceptable inertance levels across the wide range of frequency is a highly challenging job and here topography FRF optimization technique is leveraged for improving the design. Design improvements have to be made based on simulation results until the proto build phase of a vehicle program. This paper describes the investigation of inertance performance level and its improvement through simulation techniques during design phase, later on how the drive point hammer impact measurement results are utilized for correlating with FEM model for further fine tuning of the design changes before vehicle launch.