Experimental Study of an Active Window for Silent and Comfortable Vehicle Cabins

Abstract

The poor sound insulation of windows especially at low frequencies constitutes a severe problem, both in transportation and in the building sector. Due to additional constraints on vehicles or aircrafts regarding energy efficiency and lightweight construction, the demand of light-weight-compliant noise-reduction solutions is amplified in the transportation industry. Simultaneously, in order to satisfy the customer demands on visual comfort and modern design, the relative size of glazed surfaces increases in all sectors. The experimental study presented below considers the feasibility of actively controlled windows for noise reduction in passenger compartments by using the example of an automobile windshield. The active windshield consists of the passive windshield, augmented with piezoceramic actuators and sensors. The main focus of the subsequent work was the development and evaluation of feedforward and feedback control strategies with regard to interior noise reduction. The structural excitation of the windshield was realized by an electrodynamic exciter (shaker) applied at the roof brace between the A-pillars. By this choice it was possible to emulate the structural excitation of the windshield through the car body, induced by coasting and motor-force harmonics. The laboratory setup does not permit the consideration of hydrodynamic and acoustic loads, which might be important as well. However, the experimental results indicate the high noise reduction potential of active structural acoustic control of structure-borne sound that radiates into a cavity.