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Design of Multifunctional Body Panels in Automotive Applications: Reducing the Ecological and Economical footprint of the vehicle industry
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. (Lightweight Structures)
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Over the past century, the automobile has become an integral part of modern industrializedsociety. Consumer demands, regulatory legislation, and the corporate need togenerate a profit, have been the most influential factors in driving forward the evolutionof the automobile. As the comfort, safety, and reliability of the automobile haveincreased, so has its complexity, and most definitely its mass.The work within this thesis addresses the twofold problem of economy and ecologywith respect to sustainable development of automobiles. Specifically, the conflictingproblems of reducing weight, and maintaining or improving noise, vibration, andharshness behaviour are addressed. Potential solutions to these problems must also beexecutable at the same, or preferably lower production costs. The hypothesis is that byreplacing acoustic treatments, aesthetic details, and complex systems of structural componentsboth on the interior and exterior of the vehicle with a single multi-functionalbody panel, functionality can be retained at a reduced mass (i.e. reduced consumptionof raw materials) and reduced fiscal cost.A case study is performed focusing on the roof structure of a production vehicle. Fullvehicle and component level acoustic testing is performed to acquire acoustic functionalrequirements. Vibro-mechanical testing at the component level is performedto acquire structural functional requirements complimentary to those in the vehiclesdesign specifications. Finite element modelling and analysis is employed to createa model representative of the as-tested component and evaluate its acoustic and mechanicalbehaviour numerically. Results of numerical simulations are compared withthe measured results for both acoustic and mechanical response in order to verify themodel and firmly establish a set of acoustic and mechanical constraints for future work.A new, multi-layered, multi-functional sandwich panel concept is proposed which replacesthe outer sheet metal, damping treatments, transverse beams, and interior trimof the existing structure. The new panel is weight optimized to a set of structural constraintsand its acoustic properties are evaluated. Results show a significant reductionin mass compared to the existing system with no degradation of the acoustic environment.A discussion of the results is presented, as is a suggestion for future research.

Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , ix, 105 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2009:30
Keyword [en]
Sandwich panels, mutifunctional, structural acoustic interaction, NVH, vehicle acoustics
National Category
Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-10661ISBN: 978-91-7415-362-0 (print)OAI: oai:DiVA.org:kth-10661DiVA: diva2:223026
Presentation
2009-06-08, D3, KTH, Lindstedtsvägen 5, Stockholm, 13:00 (English)
Opponent
Supervisors
Available from: 2009-06-11 Created: 2009-06-10 Last updated: 2010-11-03Bibliographically approved
List of papers
1. Prediction of NVH behaviour of trimmed body components in the frequency range 100-500 Hz
Open this publication in new window or tab >>Prediction of NVH behaviour of trimmed body components in the frequency range 100-500 Hz
2010 (English)In: Applied Acoustics, ISSN 0003-682x, Vol. 71, no 8, 708-721 p.Article in journal (Refereed) Published
Abstract [en]

The work within this paper focuses on the application and validation of numerical methods for predicting the acoustic and structural NVH behaviour of trimmed body components in an automotive context. In particular, the level of modelling refinement and accuracy necessary to establish a reliable finite element analysis model for comparative purposes in the development of alternative designs is investigated. Specifically, the roof structure of a passenger car was investigated from various performance aspects, using both structural and acoustic excitation. The roof was initially tested in situ, with and without interior lining, to provide a reference for subsequent component tests. It was then detached from the car, mounted in a stiff frame and tested in a transmission window using both acoustic and structural excitation. A finite element model of the detached component was developed using shell and solid elements for the structure and solid elements for the interior lining. Predictions were carried out to evaluate the STL as well as the vibrational frequency response due to a force applied to the structure. Special attention was given to the modelling of the headliner as well as the air gap separating the headliner from the outer sheet metal. A sensitivity study of various headliner properties was performed in addition to a comparison between solutions calculated using standard Nastran elements and augmented poro-elastic elements via the software package CDH/EXEL. The main objective of the current work has been to establish a datum reference for alternative designs. From this aspect, the validation of the numerical modelling methodology, in particular the level of detail and accuracy used, was a crucial step. It was found that the predictions agreed very well with the measured data. As an additional, very interesting result, it was also found that the in situ testing correlated well with the transmission suite testing.

Keyword
NVH prediction, Trimmed body components, Finite element method, STL, Biot modelling
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-25149 (URN)10.1016/j.apacoust.2010.03.002 (DOI)000279325600004 ()2-s2.0-77955266569 (Scopus ID)
Note
QC 20101011Available from: 2010-10-11 Created: 2010-10-11 Last updated: 2017-12-12Bibliographically approved
2. Structural-acoustic Design of a Multi-functional Sandwich Panel in an Automotive Context
Open this publication in new window or tab >>Structural-acoustic Design of a Multi-functional Sandwich Panel in an Automotive Context
2010 (English)In: Journal of Sandwich Structures and Materials, ISSN 1099-6362, E-ISSN 1530-7972, Vol. 12, no 6, 684-708 p.Article in journal (Refereed) Published
Abstract [en]

This article deals with the design and weight optimization of a multi-functional vehicle body panel in an automotive context. An existing vehicle design has provided functional design requirements regarding static, dynamic, and acoustic behavior of the components of a car roof. A novel, multifunctional panel is proposed which integrates the component requirements present in a traditional roof system within a single module. The acoustic properties of two configurations of the novel panel are examined using numerical methods including advanced poro-elastic modeling tools compatible with Nastran, and compared with numerical results of a finite element model of the existing construction.

Keyword
sandwich structures, acoustic modeling, design optimization
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-25148 (URN)10.1177/1099636209359845 (DOI)000284691100002 ()2-s2.0-77954143529 (Scopus ID)
External cooperation:
Note

QC 20101011

Available from: 2010-10-11 Created: 2010-10-11 Last updated: 2017-12-12Bibliographically approved

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