BIOT’s Parameters Evaluation of Flat and Molded Sound Package Materials and Prediction of Acoustic Performance and it’s Validation 2019-26-0195
In today’s automotive industry sound package material modeling, design and optimization is important considering the need for weight reduction and achieving targeted sound absorption and sound transmission loss values. As per traditional approach vehicle level noise reduction targets are defined considering flat samples, but in actual vehicle condition molded trimmed parts are used. This paper discusses about the systematic methodology developed for molded sample characterization in terms of BIOT’s properties. Effects of different parameters like area wise thickness variation, density variation, curvature, compressed edges on BIOT properties is studied. Comparison of BIOT properties of same specification flat and molded dash sample is done to study the effect of trimmed structure. Prediction of sound absorption and sound transmission loss results carried out using FTMM approach for flat sample and SEA approach for molded sample using evaluated BIOT’s properties. These predicted results validated with experimental sound absorption measured in small cabin and sound transmission loss measured in reverberation chambers. Comparison of predicted and experimental results of flat and molded samples is done to highlight the need of molded sample characterization, prediction of it’s performance using SEA and validation with experimental results for achieving targets. Finally different suggestions are given to account critical parameters affecting the BIOT properties and in turn acoustic performance of sound package material. It can help NVH engineers for accurate design and to develop sound package material with better performance.