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A Vibro-Acoustic Study of Vehicle Suspension Systems: Experimental and Mathematical Component Approaches
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of the present work is to study the vehicle suspension as a vibro-acoustic system of high complexity, consisting of many sub-systems with fundamentally different acoustical properties. In a parallel numerical and experimental modelling effort, important contributions to the understanding of its behaviour have been achieved. These findings are based on a balance between component investigations and global modelling of the complete system; they have been formulated for the transmission of both tyre-road excitation and friction-induced vibrations in the brake system.

Initially an experimental study was conducted on a full vehicle test rig studying the broadband interior brake noise problem of, here named, roughness noise. The purpose of the study was twofold: first, to determine if the transmission from the source to the interior of the vehicle was structure-borne; second, to study the complexity of the suspension as a vibro-acoustic system. Parameters a_ecting the vibro-acoustic source were varied to gain understanding of the source mechanisms. This experimental study laid the foundation of the first part of this thesis (paper A) and provided the directions for the second part, the development of a mathematical modelling approach (paper B and C). In these two papers, methods for analysing the complex vibro-acoustic transfer of structure-borne sound in a vehicle suspension system were developed. The last part was then focussed on the wheel rim influence on the vibro-acoustic behaviour (paper D) of the suspension system. As a whole, the work clearly demonstrates that it is possible to conduct component studies of subsystems in the vehicle suspension system; and from these component studies it is possible draw conclusions that very well may avoid severe degradations in the interior noise of future vehicle generations.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , x, 61 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2013:17
Keyword [en]
Acoustics, Vehicle suspension, Disc brake, Wheel rim Roughness noise, Interior tyre-road noise Component mode synthesis, Undeformed coupling interface
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-121575ISBN: 978-91-7501-732-7 (print)OAI: oai:DiVA.org:kth-121575DiVA: diva2:619133
Public defence
2013-05-22, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:15 (English)
Opponent
Supervisors
Note

QC 20130503

Available from: 2013-05-03 Created: 2013-05-02 Last updated: 2013-05-03Bibliographically approved
List of papers
1. An experimental study of interior vehicle roughness noise from disc brake systems
Open this publication in new window or tab >>An experimental study of interior vehicle roughness noise from disc brake systems
2013 (English)In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 74, no 3, 396-406 p.Article in journal (Refereed) Published
Abstract [en]

An experimental study of the friction-induced noise generated by the disc brake system of a passenger car is presented. In particular, the brake noise usually referred to as wire brush or roughness noise is studied. This is, in terms of frequency spectral content a broadband phenomenon, resulting from the interaction of multiple asperities in the tribological contact. A new experimental method for measurements of disc brake roughness noise is proposed, and is used in a lab environment where the vehicle speed and the brake pressure are accurately controlled. The aim is to study the influence of vehicle speed and brake pressure on the roughness noise inside the vehicle. It is shown for the specific test case that the transmission from the source to the interior is a vibro-acoustic structure-borne phenomenon. Measurements show that there is a, as expected, strong correlation between increased interior noise and both increased vehicle speed and brake pressure.

Keyword
Acoustic emission, Disc brake, Surface topography, Wire brush, Roughness noise, Rubbing noise
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-117632 (URN)10.1016/j.apacoust.2012.07.011 (DOI)000312975600011 ()2-s2.0-84870027806 (Scopus ID)
Funder
Vinnova
Note

QC 20130201

Available from: 2013-02-01 Created: 2013-02-01 Last updated: 2017-12-06Bibliographically approved
2. Component mode synthesis using undeformed interface coupling modes to connect soft and stiff substructures
Open this publication in new window or tab >>Component mode synthesis using undeformed interface coupling modes to connect soft and stiff substructures
2013 (English)In: Shock and Vibration, ISSN 1070-9622, E-ISSN 1875-9203, Vol. 20, no 1, 157-170 p.Article in journal (Refereed) Published
Abstract [en]

Classical component mode synthesis methods for reduction are usually limited by the size and compatibility of the coupling interfaces. A component mode synthesis approach with constrained coupling interfaces is presented for vibro-acoustic modelling. The coupling interfaces are constrained to six displacement degrees of freedom. These degrees of freedom represent rigid interface translations and rotations respectively, retaining an undeformed interface shape. This formulation is proposed for structures with coupling between softer and stiffer substructures in which the displacement is chiefly governed by the stiffer substructure. Such may be the case for the rubber-bushing/linking arm assembly in a vehicle suspension system. The presented approach has the potential to significantly reduce the modelling size of such structures, compared with classical component mode synthesis which would be limited by the modelling size of the interfaces. The approach also eliminates problems of nonconforming meshes in the interfaces since only translation directions, rotation axes and the rotation point need to be common for the coupled substructures. Simulation results show that the approach can be used for modelling of systems that resemble a vehicle suspension. It is shown for a test case that adequate engineering accuracy can be achieved when the stiffness properties of the connecting parts are within the expected range of rubber connected to steel.

Keyword
Vibro-acoustic, component mode synthesis, substructuring, vehicle suspension, rubber bushings
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-119489 (URN)10.3233/SAV-2012-0734 (DOI)000314893500012 ()2-s2.0-84873614888 (Scopus ID)
Note

QC 20130314

Available from: 2013-03-14 Created: 2013-03-14 Last updated: 2017-12-06Bibliographically approved
3. A vibro-acoustic reduced order model using undeformed coupling interface substructuring - Application to rubber bushing isolation in vehicle suspension systems
Open this publication in new window or tab >>A vibro-acoustic reduced order model using undeformed coupling interface substructuring - Application to rubber bushing isolation in vehicle suspension systems
2014 (English)In: Applied Acoustics, ISSN 0003-682x, Vol. 78, 43-50 p.Article in journal (Refereed) Published
Abstract [en]

A vibro-acoustic reduced order model (ROM) based on a substructuring method using undeformed coupling interfaces (UCI) is proposed. The method may be used to reduce the order of a global problem, this by subdividing the global system to substructures interacting through UCI's. The local dynamic stiffness of each substructure may then be modelled with a, for that particular problem, best suited description. The feasibility of the method is demonstrated by a sensitivity analysis of the vibro-acoustic power isolation in a vehicle suspension system, comprising of a link arm connected to a vehicle car body through two rubber bushings. The link arm ROM is a component mode synthesis (CMS)-UCI, the rubber bushing model is a UCI-ROM derived from a 2D axisymmetric model using a frequency dependent visco-elastic material model. Finally the car body model is a frequency dependent UCI-ROM from a full car body finite element model. It is shown that the UCI-ROM approach efficiently can be used for parametric studies on a substructure level. The results suggest that the performed reorientation of the rubber bushings can alter, with orders of magnitude, the energy flow into the car.

Keyword
Dynamic substructuring, Reduced order modelling, Undeformed coupling interfaces, Rubber bushings, Vibro-acoustic power isolation, Vehicle suspension system
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-121571 (URN)10.1016/j.apacoust.2013.11.001 (DOI)000331926000007 ()2-s2.0-84889026635 (Scopus ID)
Note

QC 20140327. Updated from manuscript to article in journal.

Available from: 2013-05-02 Created: 2013-05-02 Last updated: 2017-12-06Bibliographically approved
4. Tyre-Road Noise: Experimental Component Investigation of the Structural Dynamic Behaviour of the Rim
Open this publication in new window or tab >>Tyre-Road Noise: Experimental Component Investigation of the Structural Dynamic Behaviour of the Rim
2013 (English)Report (Other academic)
Publisher
17 p.
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-121574 (URN)978-91-7501-752-5 (ISBN)
Available from: 2013-05-02 Created: 2013-05-02 Last updated: 2013-05-03Bibliographically approved

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