Vibro-Acoustic Modeling of the APAMAT II Test System

This paper describes the work carried out to assess the structure-borne and airborne contributions in the Rieter APAMAT II testing machine. The APAMAT II system was designed to measure the effectiveness of various trim and barrier treatments in automotive interior applications. The individual structure-borne and airborne contributions from the ball impact on the treated panel cannot be obtained directly from the sound pressure level measurements in the receiver chamber of the system.

A hybrid modeling technique is proposed that incorporates finite element (FE) and statistical energy analysis (SEA) methods to develop vibro-acoustic models across the entire frequency range for analyzing transmission characteristics of various trim configurations. This provides an analytical model that can adequately predict the vibro-acoustic response under structure-borne loads at low to mid frequencies. An SEA model was also developed to predict the transmission characteristics of various treatments at higher frequencies. Using experimental data, characterization of source loads in the system and validation tests were undertaken using the analytical models. Based on this study, the sound transmission mechanisms of the system can be used to assess the expected improvements associated with a given design change.