1、 ANSI/ASA S2.8-2007 (Revision of ANSI S2.8-1972) AMERICAN NATIONAL STANDARDTechnical Information Used for Resilient Mounting ApplicationsAccredited Standards Committee S2, Mechanical Vibration and ShockStandards Secretariat Acoustical Society of America 35 Pinelawn Road, Suite 114 E Melville, NY 117
2、47-3177 ANSI S2.8-2007 (Revision of ANSI S2.8-1972) Reaffirmed by ANSI on April 18, 2012 5HDIILUPHGE$16,0DUFKThe 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 inter
3、national standards. The 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 Inf
4、ormation Used for Resilient 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 is
5、olation for the reduction 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 r
6、esilient mountings correctly. 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 S
7、1 on Acoustics, S2 on 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
8、published by the Acoustical 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, an
9、d consumers, and to Federal, 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 S
10、tandards Secretariat administers 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 Stan
11、dards Secretariat arranges 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 re
12、ached by directly and 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 Nation
13、al Standard is completely 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 St
14、andard may be revised 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 11747-31
15、77 Telephone: 1 (631) 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. Copyrigh
16、t Act of 1976, without 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 A
17、pplications of isolation 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 ine
18、rtial bases. 11 5.7 Effect 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 Use
19、r 16 Table 2 Information 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 F
20、igure 4 Transmissibility 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-
21、2007 American National 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, Mecha
22、nical Vibration and Shock, 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 t
23、he field of mechanical 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
24、-1972, which has been 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 tim
25、e this Standard was submitted 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
26、 Association J.J. Earshen 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
27、.A.T. Herfat . M. Mezache (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.
28、 Gaydon (Alt.) MIMOSA 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 b
29、ecause sufficient technical 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 use
30、r may not be at liberty 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 app
31、ropriate technical information 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 proble
32、ms. However, it frequently 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 reg
33、arding the application 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 s
34、ystem used between an 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 Technica
35、l Information Used for 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. Ther
36、efore, use of this standard 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 pre
37、liminary technical information 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 un
38、dated references, the 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 th
39、is standard, the terms 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 trans
40、lational (or rotational) 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
41、 of America 2007 All rights 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
42、friction between adjoining 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
43、no resultant moment about 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 resil
44、ient mountings be approximately 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
45、 vibration of the equipment 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/ 20o
46、rcyc cyc cycE Fdx Fxdt 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 show
47、ed that the energy dissipation 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 sy
48、stems equivalent viscous 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 intend
49、ed function 3.8 drift (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 sub
