Concept Study on Windshield Actuation for Active Control of Wind Noise in a Passenger Car

The windshield is an integral part of almost every modern passenger car. Combined with current developments in the automotive industry such as electrification and the integration of lightweight material systems, the reduction of interior noise caused by stochastic and transient wind excitation is deemed to be an increasing challenge for future NVH measures. Active control systems have proven to be a viable alternative compared to traditional passive NVH measures in different areas. However, for windshield actuation there are neither comparative studies nor actually established actuation concepts available to the automotive industry. Based upon a numerical simulation of an installed windshield of a medium-sized car, this paper illustrates a conceptual study of both the evaluation of optimal positioning as well as a consideration of different electromechanical activation measures. A simulation model of the installed windshield is gained from an experimental modal analysis of both the windshield in free-free condition as well as in its installed configuration. The experimental data serves the frequency domain model update process of a finite element model of the installed windshield. A reduced order state space model is generated from the full second order equation of motion system matrices for a discrete time domain simulation. The acoustic behavior of the actuated windshield is taken into account by means of a feedforward Wiener digital filter solution mapping the modal velocities of the windshield to a measured sound pressure level in the passenger’s compartment. Based upon the selection of possible actuator installation positions, the acoustic sensitivity of different locations is evaluated. The conceptual study on windshield actuation is complemented by a comparison of different actuator types such as piezoelectric stack and patch actuators as well as voice coil actuation. The basic actuator concepts are also initially parametrized taking into account commercially available transducers. Based on the results of the conceptual study, the activation of the windshield is considered to be technically feasible and commercially viable.