1、 ANSI S2.8-2007 (Revision of ANSI S2.8-1972) AMERICAN NATIONAL STANDARD Technical Information Used for Resilient Mounting ApplicationsAccredited Standards Committee S2, Mechanical Vibration and Shock Standards Secretariat Acoustical Society of America 35 Pinelawn Road, Suite 114 E Melville, NY 11747
2、-3177 ANSI S2.8-2007 (Revision of ANSI S2.8-1972) Reaffirmed by ANSI on April 18, 2012 The American National Standards Institute, Inc. (ANSI) is the national coordinator of voluntary standards development and the clearinghouse in the U.S.A. for information on national and international standards. Th
3、e Acoustical Society of America (ASA) is an organization of scientists and engineers formed in 1929 to increase and diffuse the knowledge of acoustics and to promote its practical applications. ANSI S2.8-2007 (Revision of ANSI S2.8-1972) AMERICAN NATIONAL STANDARD Technical Information Used for Resi
4、lient Mounting Applications Secretariat Acoustical Society of America Approved March 22, 2007 American National Standards Institute, Inc. Abstract This standard establishes requirements to promote appropriate exchange of information regarding the application and selection of isolation for the reduct
5、ion of vibrations generated by equipment and machines. It is beyond the scope of this standard to present characteristics of resilient mountings. Rather, it is intended to outline, in standardized form, what data should be presented to enable the experienced designer to apply resilient mountings cor
6、rectly. Also, the standard defines terminology in a further effort to ease the problem of communication between user and manufacturer. AMERICAN NATIONAL STANDARDS ON ACOUSTICS The Acoustical Society of America (ASA) provides the Secretariat for Accredited Standards Committees S1 on Acoustics, S2 on
7、Mechanical Vibration and Shock, S3 on Bioacoustics, and S12 on Noise. These committees have wide representation from the technical community (manufacturers, consumers, trade associations, organizations with a general interest, and government representatives). The standards are published by the Acous
8、tical Society of America as American National Standards after approval by their respective Standards Committees and the American National Standards Institute. These standards are developed and published as a public service to provide standards useful to the public, industry, and consumers, and to Fe
9、deral, State, and local governments. Each of the accredited Standards Committees operating in accordance with procedures approved by American National Standards Institute (ANSI) is responsible for developing, voting upon, and maintaining or revising its own Standards. The ASA Standards Secretariat a
10、dministers Committee organization and activity and provides liaison between the Accredited Standards Committees and ANSI. After the Standards have been produced and adopted by the Accredited Standards Committees, and approved as American National Standards by ANSI, the ASA Standards Secretariat arra
11、nges for their publication and distribution. An American National Standard implies a consensus of those substantially concerned with its scope and provisions. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and
12、materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered and that a concerted effort be made towards their resolution. The use of an American National Standard is complet
13、ely voluntary. Their existence does not in any respect preclude anyone, whether he or she has approved the Standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the Standards. NOTICE: This American National Standard may be revised
14、or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this Standard. Acoustical Society of America ASA Secretariat 35 Pinelawn Road, Suite 114E Melville, New York 11747-3177 Telephone: 1 (631)
15、390-0215 Fax: 1 (631) 390-0217 E-mail: asastdsaip.org 2007 by Acoustical Society of America. This standard may not be reproduced in whole or in part in any form for sale, promotion, or any commercial purpose, or any purpose not falling within the provisions of the U.S. Copyright Act of 1976, without
16、 prior written permission of the publisher. For permission, address a request to the Standards Secretariat of the Acoustical Society of America. Acoustical Society of America 2007 All rights reserved iContents 1 Scope . 1 2 Normative references. 1 3 Terms and definitions. 1 4 Applications of isolati
17、on 6 5 Technical information needed for the selection and application of resilient mounting system 7 5.1 Classical model of resilient mounting 7 5.2 Transmissibility 7 5.3 Isolation efficiency. 9 5.4 Effect of damping 10 5.5 Damping and energy dissipation. 10 5.6 Effects of inertial bases. 11 5.7 Ef
18、fect of machine speed .11 5.8 Coupling of vertical motion and rocking 11 6 Requirements of the standard 12 6.1 Information supplied by the user of resilient mountings 12 6.2 Information supplied by the manufacturer of mountings. 17 Tables Table 1 Information Supplied by the User 16 Table 2 Informati
19、on Supplied by the Mounting Manufacturer. 20 Figures Figure 1 Base mounting system . 2 Figure 2 Center-of-gravity mounting system. 2 Figure 3 One-dimensional translational mass-spring-dashpot system: (a) excited by the support motion; (b) excited by force acting on the mass 7 Figure 4 Transmissibili
20、ty of mass-spring-dashpot system, 1 9 Figure 5 Mass m with moment of inertia J supported on two isolators. 12 Acoustical Society of America 2007 All rights reserved ii Foreword This Foreword is for information only, and is not a part of the American National Standard ANSI S2.8-2007 American National
21、 Standard Technical Information Used for Resilient Mounting Applications. This standard comprises a part of a group of definitions, standards, and specifications for use in mechanical vibration and shock. It was developed and approved by Accredited Standards Committee S2, Mechanical Vibration and Sh
22、ock, under its approved operating procedures. Those procedures have been accredited by the American National Standards Institute (ANSI). The Scope of Accredited Standards Committee S2 is as follows: Standards, specification, methods of measurement and test, and terminology in the field of mechanical
23、 vibration and shock, and condition monitoring and diagnostics of machines, including the effects of exposure to mechanical vibration and shock on humans, including those aspects which pertain to biological safety, tolerance and comfort. This standard is a revision of ANSI S2.8-1972, which has been
24、technically revised. This new edition has been restructured and some of the formulae, terms and definitions, and illustrations (Figures) have been revised and corrected. Additional exhibits, illustrations, and tables have been added to this revision of this document. At the time this Standard was su
25、bmitted to Accredited Standards Committee S2, Mechanical Vibration and Shock for approval, the membership was as follows: R.L. Eshleman, Chair A.T. Herfat, Vice-Chair S.B. Blaeser, Secretary Acoustical Society of America.S.I Hayek B.E. Douglas (Alt.) American Industrial Hygiene Association J.J. Ears
26、hen D. Driscoll (Alt.) Association of American Railroads.J. Moller . N. Cooperrider (Alt.) Calnetix. .L. Hawkins .P. McMullen (Alt.) Caterpillar, Inc. . D. Roley Charles M. Salter Associates . A. Nash Commercial Vehicle Group . L. Mullinix Emerson Electric Copeland Corporation .A.T. Herfat . M. Meza
27、che (Alt.) Endevco Corp B. Yang Acoustical Society of America 2007 All rights reserved iiiGE Energy R. Bankert Infrared Training Center .G. Orlove R. Madding (Alt.) John Deere. L. DeVries Lord Corporation. L. Miller A. Crocket (Alt.) Mechanical Solutions, Inc. W.D. Marscher .M. Gaydon (Alt.) MIMOSA
28、K. Bever . A. Johnston (Alt.) National Institute for Occupational Safety FAX: 631-390-0217; E-mail: asastdsaip.org Acoustical Society of America 2007 All rights reserved vIntroduction Users of resilient mountings are sometimes handicapped in applying mounting systems properly because sufficient tech
29、nical information is not furnished by the manufacturer. Consequently, the users often conduct their own experimental evaluation of mountings and perhaps unknowingly duplicate work already performed by the manufacturer. Also, in some industries and military applications, the user may not be at libert
30、y to disclose applicable information which might otherwise facilitate suggestions and recommendations by the mounting manufacturer. Hence, many times the user must acquire considerable proficiency in the art of applying resilient mountings and, in these instances, they need appropriate technical inf
31、ormation from the manufacturer. On the other hand, some manufacturers of resilient mountings have experience covering a wide variety of mounting applications. Manufacturers, in most instances, are willing to use their background information for solving the users mounting problems. However, it freque
32、ntly is difficult for the manufacturer to provide this service, because the user has not furnished sufficient information to the manufacturer regarding the application. This American National Standard is intended to serve as a guide for the exchange of technical information regarding the application
33、 of isolation for vibrations generated by equipment and machines, and for use between the customer and supplier of resilient mounting systems for their proper applications. For the purposes of this ANSI Standard, a resilient mounting system is defined as a flexible element or system used between an
34、equipment item and its supporting structure to attenuate the transmission of shock or vibration from the equipment and machine to the structure. AMERICAN NATIONAL STANDARD ANSI S2.8-2007 Acoustical Society of America 2007 All rights reserved 1American National Standard Technical Information Used for
35、 Resilient Mounting Applications 1 Scope This American National Standard establishes the requirements to promote an appropriate exchange of information regarding the application and selection of isolation for the reduction of vibrations generated by equipment and machines. Therefore, use of this sta
36、ndard can improve communication among engineers, manufacturers and end-users concerned with vibration isolation. It is beyond the scope of this standard to present characteristics of resilient mountings. Rather, it is intended to outline, in standardized form, what data and preliminary technical inf
37、ormation should be presented to enable the experienced designer to apply resilient mountings correctly. 2 Normative references The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the
38、latest edition of the referenced document (including any amendments) applies. ANSI S1.1-1994 American National Standard Acoustical Terminology ANSI S2.1-2000/ISO 2041:1990 American National Standard Vibration and shock - Vocabulary 3 Terms and definitions For the purposes of this standard, the terms
39、 and definitions given in ANSI S1.1-1994, ANSI S2.1-2000/ISO 2041:1990, and the following apply. 3.1 axial stiffness load-deflection ratio of a mounting along the line of application of the load NOTE Stiffness is the ratio of change of force to the corresponding change in translational (or rotationa
40、l) deformation of an elastic element. The stiffness can be dynamic or static, and the mounting shall have an axis of symmetry. 3.2 base mounting system system which has the resilient mountings attached underneath the mounted item (see Figure 1) ANSI S2.8-2007 Acoustical Society of America 2007 All r
41、ights reserved 2 Figure 1 Base mounting system 3.3 bottoming deflection which causes an abrupt change (usually discontinuous) of the dynamic or static stiffness of the mounting, such as is caused by mass to mass contact 3.4 breakaway force force required to overcome the static friction between adjoi
42、ning surfaces NOTE When the breakaway condition occurs the running friction is usually much less than the static friction. 3.5 center-of-gravity mounting system mounting system in which, when the mounted equipment is displaced by translation from its neutral position, there is no resultant moment ab
43、out any axis through the centre of mass (see Figure 2) NOTE 1 A center-of-gravity system has the following primary features: 1) resilient mountings located approximately in a plane passing through the center-of-gravity of the mounted item; 2) that the distance between the resilient mountings be appr
44、oximately twice the radius of gyration of the mounted item; and 3) that the horizontal-to-vertical stiffness of the resilient mounting be equal. NOTE 2 In an ideal case, if a piece of equipment is supported by a centre-of-gravity mounting system, all natural rigid body modes of vibration of the equi
45、pment on its mounts are decoupled. For example, when a translational mode is excited, no mode in the other directions will be excited. Figure 2 Center-of-gravity mounting system 3.6 damping dissipation of energy with time or distance NOTE 1 The equations for damping are: 2/ 20orcyc cyc cycE Fdx Fxdt
46、 E aX= = =(1) ANSI S2.8-2007 Acoustical Society of America 2007 All rights reserved 3Where is a proportionality constant which carries the damping information (a = c or a = 2kr); c is the damping coefficient. Results of experiments performed on a large variety of materials showed that the energy dis
47、sipation per cycle due to internal friction is roughly proportional to square of the displacement amplitude 6. NOTE 2 r = f/fnis the ratio of the excitation frequency to the natural frequency of the mass-spring system and = c/cc, called the damping ratio, is the ratio of the systems equivalent visco
48、us damping coefficient c to its critical value, cc. NOTE 3 In the context of vibration and shock, damping is the progressive reduction of the amplitude with time. 3.7 deflection limit static or dynamic deflection beyond which the mounting will not efficiently perform its intended function 3.8 drift
49、(creep) continuing deformation of a mounting under specified separate or joint effects of long-term static, oscillatory or repeated shock loads NOTE The damping material shall be used above the glass transition temperature. 3.9 dynamic stiffness ratio of the amplitude of the periodic force or torque through a mounting to the amplitude of the periodic translational or rotational displacement (in phase with that force) of the mounting when subject to steady-state vibration NOTE The frequency and amplitude of such vibrat
