Development of Prediction Method for Dynamic Strain on Windshield during Passenger Airbag Deployment

The objective of this study is to accurately predict the dynamic strain on the windshield caused by the deployment of the airbag in a short term without vehicle tests. The following assumption is made as to the dynamic pressure distribution on the windshield: The deployment of the airbag is fast enough to ignore spatial difference in the patterns of the pressure time histories. Given this assumption, significant parameters of the dynamic pressure distribution are as follows: 1) the distribution of the maximum pressure during contact between the airbag and the windshield, and 2) the characteristic of the force time histories applied to the windshield by the deploying airbag. In this study, the prediction method consists of a simplified airbag deployment test and an FE simulation. The simple deployment test was conducted to measure the peak pressure distribution between the airbag and a flat panel simulating the windshield. The pressure time history curves were determined by scaling the force time histories from the load cells. The scale factor was identified for each of the measuring points on the pressure measurement film. Prescribed pressure time histories were directly applied to the part of the FE mesh specifically used to load the windshield. In order to validate the developed prediction method, the strain from the FE simulation was compared with that from strain gauges in the vehicle tests. The results showed that the predicted strain on the windshield caused by the airbag deployment correlated well with the data measured in the vehicle tests, suggesting that the prediction method developed in this study can be a valuable tool for improving the efficiency of development.