Engineering and the Environment, University of Southampton

Knowledge and understanding
Having successfully completed the module, you will be able to:

• show awareness of the motivations for controlling noise and vibration in vehicles.
• explain the sensitivity of vehicle vibration to suspension and vehicle design parameters.
• distinguish between models of different levels of complexity for vehicle vibration.
• categorise the means of generation and transmission of noise in vehicles including the typical frequency dependence of noise sources and transmission paths.
• dentify legislation relating to vehicle noise and describe procedures for measuring vehicle noise.
• distinguish principles of noise and vibration control in vehicles and give examples.
• demonstrate familiarity with the principles of experimental methods used to analyse vehicle noise.

Cognitive (thinking) skills
Having successfully completed the module, you will be able to:

• Assess qualitatively the effect on vehicle ride of elementary design changes.
• Interpret overall sound pressure level measurements in relation to vehicle noise legislation.

Practical, subject specific skills
Having successfully completed the module, you will be able to:

• Recommend simple measurements and calculations that can be performed to investigate some common noise phenomena in vehicles.

  Module Details

  Title: Automotive II - Refinement
  Code: ISVR3004
  Year: Acoustical Engineering, Aero, Mech Part 3
  Semester: Semester 2
  

  CATS points: 10 CAT points (= 100 hours) ECTS points: NaN
  Level: Undergraduate
  Co-ordinator(s): Dr Timothy Waters, Professor Phillip Joseph

  Pre-requisites and / or co-requisites

  Minimum ability equivalent to Part II Maths and basic SDOF vibration theory

The aims of this module are to:

• To develop students’ understanding of the sources and transmission of noise in automotive vehicles.
• To develop students’ understanding of vehicle ride characteristics and design parameters affecting ride quality.

• To convey the motivations for controlling noise and vibration in vehicles
• To demonstrate the effectiveness of suspensions in reducing vehicle vibration to various road inputs, and to discuss the parameters affecting suspension isolation
• To introduce students to the sources of noise in automotive vehicles, their characteristics and the parameters affecting them.
• To facilitate an understanding of structure-borne and airborne transmission of noise in vehicles and of means to assess them, and to discuss some methods for noise control in vehicles.

Vehicle Vibration

• Introduction: ride, shake, noise
• Vibration isolation: single stage and double stage; attenuation in dBs.
• Quarter car model for vehicle vibration: modes of vibration; transmissibility from road to vehicle; effect on ride of suspension stiffness/damping and axle mass.
• Constraints on suspension softness: vehicle mass, changes in payload, anti-roll stiffness, etc.
• Automotive springs (coil, leaf, torsion bar) and dampers
• Vehicle response to road input: acceleration of single DOF system to shocks and bumps; effect of suspension springs and dampers; road roughness and the Power Spectral Density; response of quarter car model to road roughness
• Vehicle bounce and pitch: half vehicle model; modes of vibration; coupling; bounce and pitch centres; Dynamic Index; choice of front and rear ride rates; wheelbase filtering.

• Fundamentals of acoustics: physical description and quantification of sound, use of decibels; 1-D wave equation; sound propagation in 2-D and 3-D; relevance to traffic noise.
• Human response and sound quality.
• Motivation for noise control; legislation, ISO 362 drive-by test, quantitative analysis of the drive-by test
• Noise sources: engine noise; intake and exhaust noise; tyre noise; wind noise.
• Airborne sound transmission; transmission loss through panels, materials for noise control; natural frequencies and mode shapes of acoustic enclosures.
• Structure-borne sound transmission; vibration isolation, damping.
• Experimental methods for noise path separation.

The module is mainly lecture based with some sessions being dedicated to covering examples and providing tutorial support prior to the examination. To ensure continuity, two lecturers share 80% of the sessions. The remainder are given by guest lecturers on related specialist topics to give students an appreciation of the breadth of the field including staff of the consultancy unit who can give a practical perspective.

Detailed handouts are given that include all material presented in lectures.

Students are encouraged to complete exercise sheets to consolidate their understanding. Solution sheets are available where appropriate. Past examination papers are also available with model answers.

Secondary text

Fundamentals of Noise and Vibration. 1998 Chapter 7 in Vol. 1, F.J. Fahy
J.G. Walker (eds), E&FN Spon
0419227008

Foundations of Engineering Acoustics, 2000, F.J. Fahy, Academic Press
0122476654