Wang X. Vehicle Noise and Vibration Refinement

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Contributor contact details

(* = main contact)

Chapters 1, 2, 3, 4, 5, 7

and 16

Dr Xu Wang

RMIT University

School of Aerospace, Mechanical

and Manufacturing Engineering

PO Box 71, Bundoora

Victoria 3083

Australia

E-mail: xu.wang@rmit.edu.au

Chapter 6

Dr Michael Kronast

Vehicle NVH Europe

Ford-Werke GmbH

D-50725 Köln

Germany

E-mail: mkronast@ford.com

delkro@netic.de

Chapter 8

Dr Norbert Hampl

Vehicle NVH Europe

Ford-Werke GmbH

D-50725 Köln

Germany

E-mail: nhampl@ford.com

Chapter 9

Mr Thomas Ahlersmeyer

Vehicle NVH Europe

Ford-Werke GmbH

D-50725 Köln

Germany

E-mail: tahlersm@ford.com

Chapter 10

Professor Simon Watkins

RMIT University

School of Aerospace, Mechanical

and Manufacturing Engineering

PO Box 71, Bundoora

Victoria 3083

Australia

E-mail: simon.watkins@rmit.edu.au

Chapter 11

Professor Steve J. Elliott

Institute of Sound and Vibration

Research

University of Southampton

Southampton SO17 1BJ

E-mail: sje@isvr.soton.ac.uk

xii Contributor contact details

Chapter 12

Dr David C. Baillie

Engineering Department

General Motors Holden Ltd

GPO Box 1714

Melbourne

Victoria 3001

Australia

Chapter 13

Davide Vigé

Vehicle Architectures, NVH and

Aerodynamics Department

Centro Ricerche Fiat

Strada Torino, 50

10043 Orbassano

Italy

E-mail: davide.vige@crf.it; davide.

vige@ﬁ at.com

Chapter 14

Björn Reff

Vehicle NVH Europe

Ford-Werke GmbH

D-50725 Köln

Germany

E-mail: breff@ford.com

Chapter 15

Greg M. Goetchius

Material Sciences Corporation

6855 Commerce Blvd

Canton, MI 48363

USA

E-mail: greg.goetchius@matsci.com

Preface

Noise and vibration of motor vehicles are increasingly important for the

automotive industry and are concerns for both vehicle manufacturers and

component suppliers. While noise pollution legislation is driving down

vehicle exterior noise, customers are becoming more discerning in relation

to noise and vibration inside the vehicle. Noise and vibration are now con-

sidered to be two of the most important quality factors in vehicle design.

This book provides a review of noise and vibration reﬁ nement principles,

control methods and advanced experimental and modelling techniques.

There is also a review of palliative treatments necessary in vehicle design,

development and system integration processes in order to meet noise and

vibration targets and standards. A comprehensive reference list is provided

in order to direct further studies and to assist readers to develop in-depth

knowledge of the sources and transmission mechanisms of noise and vibra-

tion in motor vehicles. The book aims to support product design and devel-

opment engineers and managers in automotive engineering companies as

well as researchers and students. Chapters 1–4 and 6–8 are focused on the

introduction of fundamental principles and methods. Chapters 9–13 present

engineering case studies. Chapters 14–16 present advanced techniques.

The authors include specialists working in noise and vibration depart-

ments of major automotive manufacturers, component suppliers and uni-

versities. An additional aim of the book is to improve automotive education

and to bridge the gap between the automotive industry and universities.

The authors believe that the key to an efﬁ cient automotive industry is close

liaison between universities and industry, while maintaining a good balance

between academic and commercial needs.

xiii

Rationale and history of vehicle noise

and vibration reﬁ nement

X. WANG, RMIT University, Australia

Abstract: Vehicle noise and vibration performance are important aspects

of vehicle design validation criteria, and have signiﬁ cant inﬂ uence on the

overall image of a vehicle. This chapter summarizes the objectives and

signiﬁ cance of vehicle noise and vibration reﬁ nement, deﬁ nes its scope

and illustrates its relationship to the vehicle development process. Some

vehicle noise and vibration terms are deﬁ ned and a brief history of

motoring and vehicle reﬁ nement is presented.

Key words: noise, vibration, reﬁ nement, vehicle development process,

target setting, benchmarking, design, development, testing, validation,

audit.

1.1 Introduction

Vehicle noise and vibration performance is an important vehicle design

validation criterion, since it signiﬁ cantly affects the overall image of a

vehicle. Noise and vibration degrade the driver’s and passengers’ comfort

and induce stress, fatigue and feelings of insecurity. Modern vehicle devel-

opment requires noise and vibration reﬁ nement to deliver the proper level

of customer satisfaction and acceptance. It is common for a customer’s

perception of vehicle quality to relate closely to the noise and vibration

characteristics of the vehicle.

Globalization combined with increased competition in the marketplace

requires a vehicle’s noise and vibration characteristics to be well optimized.

The sound present in the interior of a vehicle consists mainly of powertrain

noise, road noise and wind noise. Given the increased market demand for

lighter and more powerful vehicles, it becomes evident that powertrain-

induced noise is a key component of the vehicle’s interior noise. Automotive

manufacturers are increasing the number of powertrains available on

vehicle programs because of the potential for improved fuel economy. For

example, diesel-powered vehicles are one of the popular alternatives in the

global automotive market. This presents and further complicates a unique

set of noise and vibration challenges that need to be solved during the

vehicle development process. This means not only eliminating squeaks and

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4 Vehicle noise and vibration reﬁ nement

rattles and suppressing overall noise levels, but also tuning the sound of the

automobile to reﬂ ect the high quality and distinction of the brand.

1.2 Objectives and signiﬁ cance of vehicle noise and

vibration reﬁ nement

Noise, vibration and harshness (NVH) have become increasingly important

as a result of the demand for increasing reﬁ nement. Vibration has always

been an important issue closely related to reliability and quality. Noise is

of increasing importance to vehicle users and environments. Harshness

is related to the quality and transient nature of vibration and noise. Noise

and vibration problems may originate from systems such as the engine,

pumps, drivetrain, wheels and tyres, or may be related to system integration

issues, for example matching between powertrain and body and between

chassis and body. Controlling vibration and noise in vehicles poses a

severe challenge to designers because motor vehicles have several

sources of vibration and noise which, being interrelated and speed

dependent, are different from many machine systems. Vehicle noise and

vibration reﬁ nement has been considered essential for vehicle design

and development because of legislation, marketing needs and customer

expectations. In order to minimize the impact of the automobile on the

environment, legislation has become increasingly demanding on vehicle

noise emission and vibration controls. Noise and vibration reﬁ nement

distinguishes a vehicle from its competitors, thereby attracting new

customers.

1.3 Scope of vehicle noise and vibration reﬁ nement

Vehicle reﬁ nement encompasses noise and vibration reﬁ nement, ride and

driveability. Vehicle reﬁ nement affects the customer’s buying decision and

the business of selling passenger cars, as it directly affects the driving expe-

rience. A reﬁ ned vehicle should have the following characteristics:

• High ride quality

• Good driveability

• Low wind noise

• Low road noise

• Low engine noise

• Idle reﬁ nement (low noise and vibration)

• Cruising reﬁ nement (low noise and vibration, good ride quality)

• Low transmission noise

• Low levels of shake and vibration

• Low levels of rattles, squeaks and sizzles

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Rationale and history of vehicle noise and vibration reﬁ nement 5

• Low level of exterior noise of good quality

• Low level of interior noise of good quality

• Noise that is welcome as a ‘feature’.

Customers have come to expect continuous improvement in new vehicles.

They expect their new purchase to be better equipped and more comfort-

able, and to perform better than the vehicle they have just traded in. If the

new vehicle is better in all respects than the old one, but lacks reﬁ nement,

the customer will not be fully satisﬁ ed. Vehicle reﬁ nement aims to enhance

vehicle performance, styling and acoustics. The motivations for vehicle

reﬁ nement are therefore:

• Brand image

• Drive comfort

• Quality enhancement

• Cost and weight reduction

• Customer satisfaction.

Noise and vibration reﬁ nement is an important aspect of vehicle reﬁ ne-

ment. It deals with noise and vibration suppression, noise and vibration

design, rattle and squeak suppression. The vehicle noise and vibration

reﬁ nement process covers the following tasks:

• Benchmarking

• Target setting

• Noise and vibration design and development

• Prototype NVH testing and design validation

• Noise and vibration diagnostics and problem solving

• NVH design solutions for production

• NVH audits on production vehicles.

1.4 The vehicle development process and vehicle

noise and vibration reﬁ nement

Figure 1.1 shows the four-phase vehicle development process. This

consists of program deﬁ nition (phase one), design and development (phase

two), product veriﬁ cation (phase three) and production (phase four).

Theme (phase one), content deﬁ nition and design (phase two), test (phase

three) and manufacturing and assembly (phase four) are implemented

in the four-phase process. Connection of the phases has a timing overlap.

Fuzziness in design is large at the beginning of the process and small

at the end of the process. The process cycle lasts 3–6 years. The production

volume for the process is approximately 100,000—1,000,000 vehicles per

year.

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6 Vehicle noise and vibration reﬁ nement

Phase one starts from product planning, which identiﬁ es:

• Demographic trends

• Buyer proﬁ les

• Economic trends

• Anticipated sales volumes

• Balancing economic opportunity with compliance to the strategic plan

and acceptable risks.

In phase one, market research information is analysed, the performance of

competing companies and their sales are studied, and the established

product cycles are investigated to determine whether current tooling life

has expired. Strategies for the replacement of existing models or the intro-

duction of totally new ones must be formulated. Design characteristics,

features, options and systems are determined by quality function deploy-

ment, benchmark study and existing warranty data.

Quality function deployment identiﬁ es:

• The voice of the customers

• Speciﬁ c performance targets

• Measurable processes towards the targets

• Matrices to inject the customer’s needs into the product design and

manufacturing processes.

Benchmark study provides insights into design, features, quality and price.

It identiﬁ es:

Program definition

Fuzziness in

design

Prototype(s) available

Total process time ~ 3–6 years

Production volume ~ 100 000–1 000 000 vehicles/year

Design & development

Product verification

Production

Theme Test

Assembly

Content definition & design

1.1 A four-phase vehicle development process (reproduced by

permission, Wang, X., Introduction to Motor Vehicle Design, RMIT

Publisher, 2005).

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Rationale and history of vehicle noise and vibration reﬁ nement 7

• Customer requirements

• Trends in the marketplace

• Important features.

Warranty data identiﬁ es:

• Existing design problems

• Desirable and undesirable features

• Product functions that may result in unexpected performance (such as

operator misuse, unexpected environmental conditions, or interaction

with other vehicle components).

Corresponding to the four-phase vehicle development process, some

automotive manufacturers set up a four-phase prototype vehicle develop-

ment program (Alpha, Beta, Gamma, Pilot). From the past vehicle develop-

ment program, the unsolved NVH issues are passed on to the current vehicle

development program, and NVH engineers address those issues in the

program deﬁ nition phase. Computer Aided Engineering (CAE) tools are

used for NVH design and to resolve NVH issues. Mule vehicles are built by

modifying the previous vehicle development models in the prototype Alpha

where components or system designs are installed. These component or

system designs are early prototype or concept designs. The prototype Alpha

vehicle is tested according to the experimental plan of the program. The test

data are used to validate the component or system designs of the vehicle.

NVH development, validation and audit tests are conducted on the proto-

type. In prototype Alpha, the vehicle body is usually developed from the

previous model and the prototyped powertrain may be installed.

The prototype Alpha is usually available at the beginning of the program

deﬁ nition (phase one). More component and/or system designs are added

onto the prototype Beta, the early version concept designs evolving to the

next level in the prototype based on the development, validation test and

audit data. More NVH development, validation and audit tests are con-

ducted in the prototype Beta where the early version of body structure

design is installed, the powertrain system design is upgraded, and parts of

the chassis and suspension system and component designs are installed. The

installed designs in the prototype Beta evolve into the next level based on

the prototype development test results. The prototype Beta is usually built

at the beginning of the design and development phase.

In the prototype Gamma, all component and system designs are installed.

Most of them are upgraded and ﬁ nalized for the stage of design freeze. The

prototype vehicle must pass national design rules and standards/require-

ments such as impact and crashworthiness, durability, emission and engine

calibration, pass-by noise, etc. The prototype Gamma is usually built at the

beginning of the product veriﬁ cation–test phase.

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8 Vehicle noise and vibration reﬁ nement

In the prototype Pilot, engineers focus on NVH diagnostics and trouble-

shooting, auditing vehicle NVH performance and investigating NVH issues

related to variations of the manufacturing process such as noise seals/leaks,

rattle, squeak, etc. Engineers are requested to organize vehicle NVH assess-

ment rides with a vehicle development team and engineering management,

to conduct NVH subjective evaluation and analysis, diagnose NVH prob-

lems and troubleshoot them. NVH engineers must propose low-cost, pro-

duction-friendly design solutions. They are also encouraged to drive and

audit the vehicles near the assembly plants, work and communicate with

plant engineers to sort out process-variation-related NVH issues and rein-

force the process quality control.

In parallel with the four-phase prototype vehicle tests, the component

and system designs in the four phases are concurrently tested and validated

in laboratories. There are usually two or three vehicle development program

overlaps in the typical workload of NVH engineers. These are previously

released vehicle-model service ﬁ xes, the current-vehicle development

program and the future-vehicle development program. NVH engineers are

therefore involved not only in problem solving and service ﬁ xes, but also

in research and development, as well as noise and vibration design to avoid

NVH problems at the early design stages. Figure 1.2 shows that the central

area of vehicle integration is vehicle noise and vibration reﬁ nement in

which NVH engineers investigate system matching-related NVH issues,

such as NVH issues from matching body with powertrain, matching chassis

with body and matching chassis with powertrain. Noise and vibration design

for vehicle integration is one of the key tasks in this model; CAE tools are

used in vehicle integration and noise and vibration reﬁ nement. Good com-

munication is essential between NVH engineers, CAD/CAE engineers,

vehicle integration engineers and vehicle plant engineers as shown in the

model of Fig. 1.2. Figure 1.3 shows that noise and vibration reﬁ nement is

the central area of system design and development in which the systems

include powertrain, chassis and suspension, body and trim, electrical and

HVAC; NVH engineers must compel system suppliers to resolve their

system/component NVH problems that appear in vehicle assembly and to

meet their NVH targets by the existing quality control processes.

Vehicle noise and vibration reﬁ nement is a process requiring team effort.

Good communication, a cooperative relationship and trust must be estab-

lished between NVH engineers, design and development engineers, suppli-

ers, experimental planning, CAE engineers, test technicians, program and

engineering managers for the vehicle development process in order for the

whole vehicle engineering team to feel integrated and harmonized.

Teamwork motivates the parties to generate enthusiasm and commitment,

and is conducive to a high standard of work. Communication can be con-

ducted in many ways, for example through group meetings, project and

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Rationale and history of vehicle noise and vibration reﬁ nement 9

program meetings, supplier design and development meetings, on-site

problem-solving task force meetings, test requests, work instructions, test

reports, test procedures, test result presentations, Avoid Verbal Orders

(AVOs), emails, telephone conversations, etc.

Standard steps for NVH problem solving are:

• Identify the problems in vehicle operating conditions with the relevant

engineering party on site.

• Instrument and test the vehicle, reproducing the problems under the

same vehicle operating conditions.

Chassis & suspension

Body & trim

Powertrain, electrical & HVAC

Vehicle integration

Noise & vibration refinement

1.2 Interaction model of noise and vibration reﬁ nement in vehicle

Suppliers

Powertrain, electrical & HVAC

Body & trim

Chassis & suspension

Vehicle assembly plant

Noise & vibration refinement

1.3 Interaction model of noise and vibration reﬁ nement in system

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