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1、TECHNICAL REPORT IS0 TR 11688-l First edition 1995-03-I 5 Acoustics - Recommended practice for the design of low-noise machinery and equipment - Part 1: Planning Acoustique - Pratique recommandke pour la conception de machines et d kquipements 9 bruit rkduit - Partie 7: Planification Reference numbe
2、r ISO/TR 11688-l :I 995(E) lSO/TR 116%1:199503 Contents Scope . 1 References . 1 Definitions 2 Methodical design and acoustic aspects 4 Conceptual and detailed design 5 Low-noise prototyping . 23 Final testing . 25 Annexes A Summary of design rules . 26 B Noise control requirements for design . 31 C
3、 Information to be reported . 34 D Bibliography 36 0 IS0 1995 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the
4、 publisher. International Organization for Standardization Case Postale 56 l CH-1211 Geneve 20 * Switzerland Printed in Switzerland ii 0 IS0 ISO/TR 11688-1:1995(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bod
5、ies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental a
6、nd non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the Internation Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The main task of technical committees is to prepare International Standards, but in exceptional ci
7、rcumstances a technical committee may propose the publication of a Technical Report of one of the following types: - type 1, when the required support cannot be obtained for the publication of an International Standard, despite repeated efforts; - type 2, when the subject is still under technical de
8、velopment or where for any other reason there is the future but not immediate possibility of an agreement on an International Standard; - type 3, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”,
9、for example). Technical Reports of types 1 and 2 are subject to review within three years of publication, to decide whether they can be transformed into International Standards. Technical Reports of type 3 do not necessarily have to be reviewed until the data they provide are considered to be no lon
10、ger valid or useful. ISO/TR 11688-1, which is a Technical Report of type 3, was prepared by Technical Committee lSO/TC 43, Acoustics, Subcommittee SC 1, Noise. IS0 11688 consists of the following parts, under the general title Acoustics - Recommended practice for the design of low-noise machinery an
11、d equipment: - Part 1: Planning Technical Report - Part 2: Introduction into physics of low-noise design iii -,-,- ISO/TR 11688-1:1995(E) (Q IS0 Introduction This lnternational Technical Report provides a guideline for the design of low-noise machinery. Most of the existing International Technical R
12、eports prepared in lSO/TC 43/SC 1 specify methods for the measurement and/or evaluation of noise. The final objective of this International Technical Report, however, will be noise control in existing machinery and noise control at the design stage. It is important that non-acoustic engineers are en
13、gaged in noise control practice. It is of great importance for these engineers to have a basic knowledge of noise generation and propagation characteristics and to understand the basic principles of noise control measures. Hence, this lnternational Technical Report also serves as an introduction int
14、o acoustical terms, and as a basis to the acquisition of further knowledge in noise control. It is strongly required to support the dissemination of the design rules given here through standardisation. Such considerations have led to the preparation of International Technical Reports in the area of
15、noise control. iv TECHNICAL REPORT Q IS0 ISO/TR 11688-1:1995(E) Acoustics - Recommended practice for the design of low-noise machinery and equipment - Part 1: Planning 1 Scope This International Technical Report is an aid to understanding the basic concepts of noise control in machinery and equipmen
16、t. The recommended practice presented here is intended to assist the designer at any design stage to control the noise of the final product. Methodical development of products was chosen as a basis for the structure of this document (see Clause 4). The list of design rules given in this Internationa
17、l Technical Report is not exhaustive. Other technical measures for reducing noise at the design stage may be used if their efficacy is identical or higher. To solve problems going beyond the scope of this International Technical Report, the designer can refer to the bibliography in Annex D, which pr
18、esents the general state of acoustic handbooks at the time of publication. Furthermore, reference is made to the numerous technical publications dealing with acoustical problems. 2 References IS0 3744: 1994, Acoustics - Determination of sound power levels of noise sources using sound pressure - Engi
19、neering method in an essentially free field over a reflecting plane. IS0 3746:-l), Acoustics - Determination of sound power levels of noise sources - Survey method employing an enveloping measurement surface over a reflecting plane. IS0 4871 :- ), Acoustics - Declaration and verification of noise em
20、ission values of machinery and equipment. IS0 9611 :- I Acoustics - Characterization of sources of structure-borne sound with respect to the airborne sound radiaiion of connected structures - Measurement of velocity at the contact points of machinery when resiliently mounted. IS0 9614-1:1994, Acoust
21、ics - Determination of sound power levels of noise sources using sound intensity - Part I: Measurement at discrete points. IS0 9614-2:-l), Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 2: Measurement by scanning. I) To be published. 1 -,-,- ISO/TR 1168
22、8-1:1995(E) Q IS0 IS0 11200:- I, Acoustics - Noise emitted by machinery and equipment - Guidelines for the use of basic standards for the determination of emission sound pressure levels at the work station and at other specified positions. IS0 11689:- I, Acoustics - Systematic collection and compari
23、son of noise-emission data for machinery and equipment. 3 Definitions For the purpose of this international Technical Report the following definitions apply: 3.7 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.70 3.7 I Airborne, liquid-borne and structure-borne noise: Sound propagating through air, a liquid or a
24、solid structure, respectively. Active noise components: Components of machinery, which generate noise. In many cases these are the power converting devices generating mechanical work from power resources, such as electrical, mechanical or magnetic energy, hydraulic pressure, internal forces, or fric
25、tion. Other noise “components” may be regions with non-steady flow and contact surfaces between moving parts. Passive noise components: Components which transmit noise generated by the active components; they do not contain noise sources but can be dominating radiators of noise. Typical passive comp
26、onents are structural parts and covering panels of machinery. Periodic noise: A noise event which is periodically repeated. Typical sources of periodic noise are gear wheels and piston machines. It is characteristic for periodic noise that it exhibits a line spectrum. Tonal noise: Noise which is dom
27、inated by one or several clearly distinguishable tone(s). Broad band noise: Noise generated by either single shocks, i.e. short duration pressure pulses or impacts, or by turbulence in an air or fluid flow. The characteristics of broad band noise are that the frequency analysis shows a continuous sp
28、ectrum over a large frequency range. Force excitation: The excitation force is independent of the properties of the excited structure; an example of this is the effect of a light and flexible source on a relatively stiff and heavy structure. Velocity excitation: The excitation velocity is independen
29、t of the properties of the excited structure; an example of this is a light and flexible structure excited by a relatively massive source. Quasi-static response: Response of the machine at frequencies below the lowest resonant frequency. Resonant response: Response in a frequency range of distinct r
30、esonances. Multi-resonant response: Response in a frequency range with many resonances. 0 IS0 ISO/TR 11688-1:1995(E) Design process Noise con trot 1 Design task 1 -c 1. Clarification of task - ciarifying standards, reauirements. state of 4 the art - list of specifications I I 2. Conceptual design -
31、search for solution II, principles 4 - comparison of different concepts - selection of concept 3- 3. Design and detail - choice of dimensions, material + - comparison (calculation 4 and modelling) - selection of detailed design I + 4. Prototyping - measurements on prototype c - evaluation of noise b
32、ehaviour - comparison with references Requirements concerning noise behaviour from - standards, authorities - regulations of clients, state of the art, competition, sales argument - own experience 4coustical experience and knowledge for comparison of different solutions - acoustical rules - rough fo
33、rmulae - diagnosis information - experience and examples - literature, drawings - acoustical modelling and FEM - acoustic devices - source strengths of partial sources (airborne, structure-borne, liquid-borne) L Noise measurement and 1 noise reduction using the prototype - analysis and modification
34、- acoustical diagnosis -final testing 1 - comparison with the requirements Clearance for series Fig. 1: Stages of the design procedure; support of design process by noise control methods 3 -,-,- ISO/TR 11599-1:1995(E) Q IS0 4 Methodical design and acoustic aspects Methodical design is an operational
35、 approach which makes use of information from a variety of disciplines, for example machine acoustics. This way a basis is set for achieving targets and making decisions in design and development. The design procedure can be divided into four phases (listed below) which are increasingly specific (se
36、e Fig. 1). Increase of information from phase to phase makes it possible to sort alternative solutions with respect to specific design criteria such as low noise level. The phases of systematic design are: 1. Clarification of task: Make a list of requirements which is the controlling document for th
37、e whole design task. Include noise specifications in this list with reference to legislation, the state of the art, competitors products, client demand or the weighting of machine noise as a company sales argument. (See Annex 6.) 2. Conceptional design: This phase of the design process concentrates
38、mainly on achieving the desired objectives. Little information is available about the final product at this stage and the noise behaviour is often assessed by comparison to known designs. 3. Design and detail: As the design and choice of individual components progress, quantitative estimates of nois
39、e behaviour can be made through the selection of design options. 4. Prototyping: Measurements on the prototype allow quantification of major noise sources and sound paths. This may indicate specific measures leading to design changes. Compliance with the requirements can be confirmed by measurements
40、. The following procedure can be applied in each of the four phases described above. It is very important to follow the methodology of eliminating the most dominant noise problems in the earliest possible stage of design: The first step of the process is determining the major sources of noise in the
41、 machine and establishing a priority list or scheme (see 5.2). Once the major sources are recognised, a more detailed analysis of the noise mechanisms must be carried out (see 5.3). The next step is analysing and describing the direct radiation of noise from the sources to the receiving position(s),
42、 and the transmission through the structure to the radiating surfaces (see 5.4). The final step is to analyse the radiation from those surfaces and to determine the various contributions to the sound pressure level at the receiving position(s). Evaluate which combination of noise control measures is
43、 optimal. In designing low-noise machinery one should try to identify the basic acoustic mechanisms involved by consideration of the causal chain (Fig. 2). All design processes have a recursive element. So at every phase a decision has to be made as to whether the next phase can be entered or whethe
44、r previous steps shall be repeated. -,-,- 0 IS0 ISO/TR 11688-f:1995(E) Acoustical mechanism Part of machinery Generation I Transmission I Radiation Fig. 2: Causal chain of noise generation An illustration of how the different noise mechanisms are connected is shown in Fig. 3. The first priority in n
45、oise control is to identify the source. Different types of sources are shown in the first and second ring with key words corresponding to the headlines of the following clauses. Once the source type is determined, transmission through the particular medium will take place as seen in the third ring.
46、Finally the noise will radiate into free air or excite a structure. The figure can be used to show that every sound source has its own characteristics, its specific transmission path through the structure and excitation of the radiating surfaces. To control the noise from a machine with many differe
47、nt types of sources, it is necessary to analyse each noise source, transmission path and radiating surface on its own to be able to evaluate the relative importance. The next clause shows an example of such a machine. 5 Conceptual and detailed design 5.7 General Since a design solution always compri
48、ses the choice of a physical operating principle and the choice of a functional system, it is possible to make the following general comments for the choice of design concepts. With a high degree of probability, the mode of operation with the lowest speed and acceleration will provide the best acous
49、tic solution. For a given operational principle the noise from a machine can be reduced by altering the mass, stiffness and damping of the structure. Design parameters such as material, shape, position, number of elements, dimensions, structure and type of connections can have a large effect on the noise emission. If applied in the proper way such alterations may reduce the vibration and/or radiation of the m