A test and simulation based approach for measuring and predicting enclosure acoustic modes at low frequencies

摘要

Correlation of enclosure acoustic modes between tests and numerical modeling at low frequencies between 50-200 Hz can be challenging. This is particularly true for enclosure systems that contain many large objects, sound sources, openings, as well as physical challenges of high temperatures, rotating parts and tight spaces. The aim of this project was to develop a methodology to measure the acoustic modes of a diesel engine compartment and correlate the measurement with simulation. This paper explains a process that used transfer functions and sound pressure mapping along with finite element analysis (FEA) and boundary element analysis (BEA) to obtain the mode shapes and frequencies. Good mode shape correlation was achieved for all modes in the frequency range of interest. Good modal frequency correlation was obtained for the first 5 enclosure modes between FEA and BEA (+ 3Hz) and between tests and simulation (+8Hz). Key steps to obtaining these results are presented in the paper.