Automated updating of simplified component models for exhaust system dynamics simulations

Document type: Conference Papers
Peer reviewed: Yes
Author(s): Thomas Englund, Johan Wall, Kjell Ahlin, Göran Broman
Title: Automated updating of simplified component models for exhaust system dynamics simulations
Conference name: The 2nd WSEAS International Conference on simulation, modelling and optimization
Year: 2002
Publisher: WSEAS
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Mechanical Engineering (Sektionen för teknik – avd. för maskinteknik)
School of Engineering S- 371 79 Karlskrona
+46 455 38 50 00
http://www.bth.se/ing/
Authors e-mail: johan.wall@bth.se
Language: English
Abstract: To facilitate overall lay-out optimisation simplified component models for dynamics simulations of automobile exhaust systems are desired. Such optimisation could otherwise be computationally expensive, especially when non-linear analyses are necessary. Suggestions of simplified models of the mufflers and the catalyst are given. To account for the flexibility at the connections between those components and the pipes short beam elements with individual properties are introduced at these locations. An automated updating procedure is developed to determine the properties of these beam elements. Results from an experimental modal analysis are used as the reference. The theoretical model of the exhaust system is built in the finite element software ABAQUS. The updating procedure uses the sequential quadratic programming algorithm included in the Optimization Toolbox of the software MATLAB to minimise the sum of the differences between experimentally and theoretically obtained natural frequencies. Constraints are used on the correlation between the experimentally and theoretically obtained mode shapes by considering the MAC-matrix. Communication between the two software packages is established by an in-house MATLAB script. The correlation between results from the updated theoretical model and the experimental results is very good, which indicates that the updating procedure works well.
Subject: Mechanical Engineering\Structural Dynamics
Keywords: Correlation, Dynamic, Exhaust system, Modal analysis, Optimisation, Updating
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