2009-01-2239 Modeling Interior Noise in Off-Highway Trucks using Statistical Energy Analysis Rohit Gujarathi, David Copley and Richard Romick Caterpillar Inc. Mohan Rao Michigan Technological University Copyright © 2009 SAE International ABSTRACT The objective of this project was to model and study the interior noise in an Off-Highway Truck cab using Statistical Energy Analys is (SEA). The analysis was performed using two different modeling techniques. In the first method, the structur al members of the cab were modeled along with the panels and the interior cavity. In the second method, the structural members were not modeled and only the acoustic cavity and panels were modeled. Comparison was done between the model with structural members and without structural members to evaluate the necessity of modeling the structure. Correlation between model prediction of interior sound pressure and test data was performed for eight different load conditions. Power contribution analysis was performed to find dominant paths and 1/3 rd octave band frequencies. INTRODUCTION The cab is an integral part of mining and construction machines like Off-Highway Trucks, Motor Graders, Excavators, Wheel Loaders, Track type Tractors, etc. It serves two different purposes: 1. Operator protection from weather and potential hazards such as falling objects. 2. Operator comfort relative to sound, dust, rain, and temperature. Hence, it is important to design quieter cabs for construction and mining machines. One of the tools that can be used very effectively early in the design process is SEA, as it allows for quick multiple iterations before the design freeze. SEA has been widely used in variety of applications. Few of these applications include airplanes [1], automobiles [2-7] and off-highway vehicles [8]. SEA MODEL DEVELOPMENT SEA GEOMETRY BUILDING - The SEA model of the cab was built using VA One software. CAD software was used to simplify the geometry of cab before importing it into the VA One software. Systems such as the HVAC unit, steering system, brakes et c. were removed as they are not physically modeled in a SEA model. The simplified geometry was imported in the VA One software and used as a basis for creating the SEA geometry. The SEA model was created using two different techniques. In the fi rst method the, three types of subsystems were created: metal and glass panels, structural members and the interior air cavity. In the second method the structural members were not modeled and only the panels and air cavity were modeled. The structural members are also called Roll Over Protection System (ROPS). The Engineering Meetings Board has approved this paper for publication. It has su ccessfully completed SAE’s peer review process under the supervision of the session organizer. This process requires a minimum of three (3) reviews by industry experts. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form o r by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. ISSN 0148-7191 Positions and opinions advanced in this paper are those of the author(s) and not nec essarily those of SAE. The author is solely responsible for the content of the paper. SAE Customer Service: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: [email protected] SAE Web Address: http://www.sae.org Printed in USA Downloaded from SAE International by University of New South Wales, Sunday, August 19, 2018 Figure 1. VA One model with ROPS and Panels Figure 2. VA One model without ROPS Two different modeling techniques were used due to the following reasons: 1. Modeling effort fo