Enhanced Windshield CAE NVH Model for Interior Cabin Noise

This paper describes a reliable CAE methodology to model the linear vibratory behavior of windshields. The windshield is an important component in vehicle NVH performance. It plays an integral role in interior cabin noise. The windshield acts as a large panel typically oriented near vertical at the front of vehicle’s acoustic cavity, hence modeling it accurately is essential to have a reliable prediction of cabin interior noise.

The challenge to model the windshield accurately rises from the structural composition of different types of windshields. For automotive applications, windshields come in several structural compositions today. In this paper, we will discuss two types of windshield glass used primarily by automotive manufacturers. First type is the typical laminated glass with polyvinyl butyral (PVB) layer and second type is the acoustic glass with PVB and vinyl layers. Acoustic glass improves acoustic characteristics of the glass in a frequency range of ~ 1200 Hz to ~4000 Hz. Low frequency interior cabin noise studied with Finite Element Analysis (FEA) is typically below 400 Hz. The acoustic glass doesn’t provide substantial benefits in this range and in many cases we see an adverse contribution at lower frequencies since the acoustic windshield tend to be softer. In this paper, frequency dependency of PVB layer and acoustic vinyl layers are investigated. Multiple modeling techniques for windshield are demonstrated and the results are compared to physical tests. Finally an enhanced windshield modeling technique for low frequency interior cabin noise is proposed.