A Sensitivity Study on Inertance Frequency Response Function through Non-Parametric Variability Approach

In recent years, there is increasing demand for every CAE engineer on their confidence level of the virtual simulation results due to the upfront robust design requirement during early stage of an automotive product development. Apart from vehicle feel factor NVH characteristics, there are certain vibration target requirements at system or component level which need to be addressed during design stage itself in order to achieve the desired functioning during vehicle operating conditions. Vehicle passive safety system is one which primarily consists of acceleration sensors, control module and air-bag deployment system. Control module’s decision is based on accelerometer sensor signals so that its mounting locations should meet the sufficient inertance or dynamic stiffness performance in order to avoid distortion in signals due to its structural resonances. During design stage, the inertance or dynamic stiffness can be assessed through the finite element (FE) based technique of modal frequency response function (FRF) analysis. FE model is deterministic and the modal frequency response function results are sensitive to the modeling techniques especially at the high frequencies due to the high modal densities. Hence the correlation of FRF results between test and simulation are highly challenging especially at the mid and high frequency band. In this paper a passive safety system control module mounting bracket is considered for the drive point FRF analysis and the correlation at system level is performed by simulating the physical bench test condition. The non-parametric variability method (NPVM) approach is used to study the system level vibration response variations due to the uncertainties in finite element modeling. Finally the updating of finite element model is made to improve the correlation level in terms of covering the test FRF response within FE results variability envelope is also highlighted in this scope of study.