Assessment of Lightweight Automotive Glass Solutions on Interior Noise Levels & Sound Quality

The automotive industry continues to develop technologies for reducing vehicle fuel consumption. Specifically, vehicle lightweighting is expected to be a key enabler for achieving fleet CO2 reduction targets for 2025 and beyond. Hybrid glass laminates that incorporate fusion draw and ion exchange innovations are thinner and thereby, offer more than 30% weight reduction compared to conventional automotive laminates. These lightweight hybrid laminates provide additional benefits, including improved toughness and superior optics. However, glazing weight reduction leads to an increase in transmission of sound through the laminates for certain frequencies. This paper documents a study that uses a systematic test-based approach to understand the sensitivity of interior vehicle noise behavior to changes in acoustic attenuation driven by installation of lightweight glass. Specifically, this study evaluates the influence of a lightweight windshield on wind, road, and powertrain contributions to vehicle interior noise. To facilitate this assessment, operating tests were conducted utilizing variable operating conditions and road surfaces such that varying balances of powertrain, wind, and road-induced interior vehicle noise could be evaluated. A time-domain noise transfer path analysis (TPA) was conducted, including multiple sources to quantify the contributions of powertrain, wind, and tire-induced noise. Prototype glass treatments were installed, and differences in measured airborne noise transfer functions were used to update the TPA model for interior noise prediction. To eliminate the influence of test reproducibility, a consistent set of "source" data was used throughout this study. Based on the results of the iterative TPA analysis, the influence of glass acoustic performance on interior sound was assessed. The use of a time-domain TPA process facilitated both subjective and objective assessment of interior sound quality. Based on the results from this analysis, minimal degradation was observed in vehicle-level NVH performance using the hybrid laminate comprising of lightweight glass, relative to conventional laminate and the lightweight glass was assessed to be a viable enabler for the vehicle application considered.