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The growing trend in demand for vehicles with diesel engines, especially in Europe, is a result of consumer demand for vehicles that offer greater fuel economy. This trend is gaining attention in North America as well. However, diesel vehicles are notorious for their NVH issues including engine vibrations that reverberate through the passenger cabin and noise that transmit through windshields as both structure-borne noise and airborne noise. Windshields, normally seen as the big hole in the front of the vehicle through which noise passes into the vehicle cabin, can be transformed to provide noise-mitigating properties by redesigning the PVB interlayer to reduce noise entering the vehicle. In essence, an acoustical windshield can help dissipate noises to a significant degree. NVH testing was performed on vehicles with diesel engines and acoustical-grade windshields, and vehicles with diesel engines and windshields made with standard PVB.

Polyvinyl butyral (PVB) is used in laminated side glass on a number of automobiles. Protection against intrusion and vandalism and reduction of interior noise are two of the major benefits of PVB laminated side glass. While standard laminated glass performs to today's specifications, testing reveals new interlayer formulations of plasticized PVB, i.e., PVB/PET/PVB composite interlayer, have resulted in laminated side glass that shows enhanced intrusion resistance performance and maintains sound insulation property of standard laminated glass. The PVB layers perform their traditional task of intrusion prevention and noise reduction, while the PET layer provides stiffness to prevent collapse or pullout. Because of its multilayer composite structure, new performance features such as improved solar protection can also be added by modifying the composite interlayer structure.

Windshields, with their low internal damping, are an acoustical weak link in automotive glazing. In the past, acoustically-enhanced glass products were typically achieved by utilizing solid and mass product design elements to increase the glass thickness. This is no longer acceptable as automakers are interested in weight savings, especially as they develop vehicles that are more fuel-efficient. Laminated safety glass, with a standard polyvinyl butyral (PVB) interlayer, is used extensively for automotive windshields and side glazing, and offers improved acoustical performance over tempered glass. However, the standard PVB interlayer is not designed specifically for acoustical and Noise, Vibration and Harshness (NVH) purposes. Studies of the parameters affecting acoustical properties and actual noise reduction capability of standard laminated glass led to the development of an acoustical grade PVB interlayer.

Polyvinyl butyral (PVB) is used in laminated side glass on several new vehicles. One of the major benefits of PVB-laminated side glass is the reduction of interior noise. To quantify this benefit, Solutia commissioned NVH testing of an S80® passenger car from Volvo with factory-equipped laminate side glass, comparing that with factory-equipped tempered glass. The noise source was a tractor-trailer truck traveling side-by-side with the vehicle. Significant noise reduction was noted (-2-6 dB in the 2k - 6k Hz range). The dampening characteristics of the PVB laminate interlayer reduced wind noise and greatly reduced traffic noise entering the cabin. A secondary benefit is that the NVH reduction was achieved while lowering the weight of the side glass by 11%. In this paper, results of the S80 vehicle testing will be reviewed and comparisons to conventional tempered glass shown. Also discussed will be OEMs, including Audi and Peugeot, which are marketing this benefit to customers.

Noise transmission through automotive windshields is the subject of extensive laboratory acoustic and full scale high-speed track NVH evaluation. Standard windshields transmit structure-borne noise through resonances at low frequencies, and wind noise and airborne noise due to coincident effect at high frequencies. Approaches to enhance windshields NVH performance and to improve vehicle interior noise quality are explored. The study shows that the most effective approach is to design a new interlayer for windshields. This leads to the development of an acoustic grade PVB interlayer. To quantify the noise reduction by windshields with the new PVB interlayer, Solutia commissioned NVH testing of the windshields installed on cars, comparing these with factory-equipped standard windshields. Dynamic responses of the windshields were studied in laboratory on a dynamometer and resulting frequency response functions measured.