1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 7626-1:2011Mechanical vibration and shock Experimental determinationof mechanical mobilityPart 1: Basic terms and definitions, andtransducer specificationsBS ISO 7626-1:20
2、11 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 7626-1:2011. Itsupersedes BS 6897-1:1987 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee GME/21, Mechanical vibration, shock and conditionmonitoring.A list of orga
3、nizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 67347 4ICS 01.040.17; 17.160Compliance with a British St
4、andard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 August 2011.Amendments issued since publicationDate Text affectedBS ISO 7626-1:2011Reference numberISO 7626-1:2011(E)ISO 2011INTERNATIONAL S
5、TANDARD ISO7626-1Second edition2011-07-15Mechanical vibration and shock Experimental determination of mechanical mobility Part 1: Basic terms and definitions, and transducer specifications Vibrations et chocs mcaniques Dtermination exprimentale de la mobilit mcanique Partie 1: Termes et dfinitions f
6、ondamentaux et spcification des transducteurs BS ISO 7626-1:2011ISO 7626-1:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2011 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 photoco
7、pying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switze
8、rland ii ISO 2011 All rights reservedBS ISO 7626-1:2011ISO 7626-1:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv 1 Scope 1 2 Normative references 1 3 Terms, definitions, and symbols . 2 3.1 Terms and definitions . 2 3.2 Symbols 8 4 Fundamentals and general relationships . 8 5 Basi
9、c requirements for force and motion measurement transducers . 9 5.1 General . 9 5.2 Requirements for motion measurement transducers . 9 5.3 Requirements for force measurement transducers . 10 5.4 Requirements for impedance heads and attachments to the structure under test . 10 6 Calibration 11 6.1 G
10、eneral . 11 6.2 Operational calibrations . 11 6.3 Basic and supplementary transducer calibrations 11 7 Basic piezoelectric transducer calibrations . 12 7.1 General . 12 7.2 Sensitivity . 12 7.3 Frequency response . 14 7.4 Accelerometer transverse sensitivity 15 7.5 Mass 15 7.6 Dimensions 15 7.7 Elec
11、trical impedance . 15 7.8 Polarity 16 8 Supplementary calibrations . 16 8.1 General . 16 8.2 Linearity 16 8.3 Effective end mass of force transducers and impedance heads . 17 8.4 Compliance of impedance heads 17 8.5 Supplementary calibrations necessitated by environmental and secondary effects 17 9
12、Presentation of data 19 9.1 General . 19 9.2 Logarithmic plotting 19 9.3 Alternative plotting methods 19 Annex A (informative) Relationship between mechanical impedance, mobility and modal analysis 23 Annex B (informative) Mobility as a frequency-response function . 26 Annex C (informative) Determin
13、ation of impedance head attachment compliance and damping . 28 Bibliography 30 BS ISO 7626-1:2011ISO 7626-1:2011(E) iv ISO 2011 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of
14、 preparing International Standards is normally carried out through ISO 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, governmental and non-governmental
15、, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main
16、task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Atten
17、tion is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 7626-1 was prepared by Technical Committee ISO/TC 108, Mechanical vibration, shock and condition monit
18、oring. This second edition cancels and replaces the first edition (ISO 7626-1:1986), which has been technically revised. ISO 7626 consists of the following parts, under the general title Mechanical vibration and shock Experimental determination of mechanical mobility: Part 1: Basic terms and definit
19、ions, and transducer specifications Part 2: Measurements using single-point translation excitation with an attached vibration exciter Part 5: Measurements using impact excitation with an exciter which is not attached to the structure BS ISO 7626-1:2011INTERNATIONAL STANDARD ISO 7626-1:2011(E) ISO 20
20、11 All rights reserved 1Mechanical vibration and shock Experimental determination of mechanical mobility Part 1: Basic terms and definitions, and transducer specifications 1 Scope This part of ISO 7626 defines basic terms and specifies the calibration tests, environmental tests and physical measurem
21、ents necessary to determine the suitability of impedance heads, force transducers and motion response transducers for use in measuring mechanical mobility. Primarily, it provides guidelines for the selection, calibration and evaluation of the transducers and instruments for their suitability in maki
22、ng mobility measurements. Procedures for carrying out mobility measurements in various circumstances are dealt with in subsequent parts of this International Standard. This part of ISO 7626 is limited to information which is basic to various types of driving-point and transfer mobility, accelerance
23、and dynamic compliance measurements. Measurements of the blocked impedance are not dealt with. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest ed
24、ition of the referenced document (including any amendments) applies. ISO 2041:2009, Mechanical vibration,shock and condition monitoring Vocabulary ISO 5347 (all parts), Methods for the calibration of vibration and shock pick-ups ISO 16063 (all parts), Methods for the calibration of vibration and sho
25、ck transducers IEC 60263, Scales and sizes for plotting frequency characteristics and polar diagrams BS ISO 7626-1:2011ISO 7626-1:2011(E) 2 ISO 2011 All rights reserved3 Terms, definitions, and symbols 3.1 Terms and definitions For the purpose of this document, the terms and definitions given in ISO
26、 2041 and the following apply. NOTE As this part of ISO 7626 deals with mechanical mobility, the notes to the definitions below provide more detail than is given in ISO 2041. 3.1.1 frequency-response function frequency-dependent ratio of the motion-response Fourier transform to the Fourier transform
27、 of the excitation force of a linear system NOTE 1 Excitation can be harmonic, random or transient functions of time. The frequency-response function does not depend on the type of excitation function if the tested structure can be considered as a linear system in a certain range of the excitation o
28、r response. In such a case, the test results obtained with one type of excitation can be used for estimating the response of the system to any other type of excitation. Phasors and their equivalents for random and transient excitation are discussed in Annex B. NOTE 2 Linearity of the system is a con
29、dition which, in practice, is met only approximately, depending on the type of system and on the magnitude of the input. Care has to be taken to avoid non-linear effects, particularly when applying impulse excitation. Structures which are known to be non-linear (e.g. certain riveted structures) shou
30、ld not be tested with impulse excitation and great care is required when using random excitation for testing such structures. NOTE 3 Motion may be expressed in terms of velocity, acceleration or displacement; the corresponding frequency-response function designations are mobility (sometimes called m
31、echanical admittance), accelerance (sometimes unfortunately called inertance; this term should be avoided because it is in conflict with the common definition of acoustic inertance and also contrary to the implication carried by the term inertance) and dynamic compliance (sometimes called receptance
32、), respectively. These are summarized in Table 1. Each of these frequency-response functions is the phasor of the motion response at a point on a structure due to a unit force (or moment) excitation. The magnitude and the phase of these functions are frequency dependent. Typical magnitude graphs for
33、 accelerance and for dynamic compliance, corresponding to the mobility graph shown in Figure 1, are shown in Figures 2 and 3, respectively. NOTE 4 Frequency response functions can be further differentiated as a) driving point response function, where the excitation and response are measured at the s
34、ame location for the evaluation of the frequency-response function, e.g. the use of an impedance head for the measurements (i j in the formulae in Table 1); b) transfer response function, where the excitation and response are not measured at the same location for the evaluation of the frequency-resp
35、onse function (i j in the formulae in Table 1). NOTE 5 Adapted from ISO 2041:2009, 1.53. 3.1.2 mobility mechanical mobility Yijcomplex ratio of the velocity, taken at point i in the mechanical system, to the excitation force, taken at the same or another point in the system NOTE 1 Mobility is the ra
36、tio of the complex velocity-response at point i to the complex excitation force at point j with all other measurement points on the structure allowed to respond freely without any constraints other than those constraints which represent the normal support of the structure in its intended application
37、. NOTE 2 The term “point” designates both a location and a direction. NOTE 3 The velocity response can be either translational or rotational, and the excitation force can be either a rectilinear force or a moment. BS ISO 7626-1:2011ISO 7626-1:2011(E) ISO 2011 All rights reserved 3NOTE 4 If the veloc
38、ity response measured is a translational one and if the excitation force applied is a rectilinear one, the units of the mobility term are m/(Ns) in the SI system. A typical graph is shown in Figure 1. NOTE 5 Mechanical mobility is the matrix inverse of mechanical impedance. NOTE 6 Adapted from ISO 2
39、041:2009, 1.54. 3.1.3 blocked impedance Zijimpedance at the input when all output degrees of freedom are connected to a load of infinite mechanical impedance NOTE 1 Blocked impedance is the frequency-response function formed by the complex ratio of the blocking or driving-point force response at poi
40、nt i to the applied excitation velocity at point j, with all other measurement points on the structure blocked, i.e. constrained to have zero velocity. NOTE 2 All forces and moments necessary to constrain fully all points of interest on the structure need to be measured in order to obtain a valid bl
41、ocked impedance matrix. Blocked impedance measurements (see Reference 16) are, therefore, seldom made and are not dealt with in the various parts of this International Standard. NOTE 3 Any change in the number of measurement points or their location changes the blocked impedances at all measurement
42、points. NOTE 4 The primary usefulness of blocked impedance is in the mathematical modelling of a structure using lumped mass, stiffness and damping elements or finite element techniques. When combining or comparing such mathematical models with experimental mobility data, it is necessary to convert
43、the analytical blocked impedance matrix into a mobility matrix, or vice versa, as discussed in Annex A. NOTE 5 Adapted from ISO 2041:2009, 1.52. 3.1.4 free impedance Z ratio of the applied excitation complex force to the resulting complex velocity with all other connection points of the system free,
44、 i.e. having zero restraining forces NOTE 1 Historically, often no distinction has been made between blocked impedance and free impedance. Caution should, therefore, be exercised in interpreting published data. NOTE 2 Free impedance is the arithmetic reciprocal of a single element of the mobility ma
45、trix. While experimentally determined free impedances could be assembled into a matrix, this matrix would be quite different from the blocked impedance matrix resulting from mathematical modelling of the structure and, therefore, would not conform to the requirements for using mechanical impedance i
46、n an overall theoretical analysis of the system. NOTE 3 Adapted from ISO 2041:2009, 1.51. 3.1.5 frequency range of interest span between the lowest frequency to the highest frequency at which mobility data are to be obtained in a given test series BS ISO 7626-1:2011ISO 7626-1:2011(E) 4 ISO 2011 All
47、rights reservedTable 1 Equivalent definitions to be used for various kinds of frequency-response functions related to mechanical mobility Motion expressed as velocity Motion expressed as acceleration Motion expressed as displacement Term Symbol Unit Boundary conditions See MobilityaYij vi/Fjm/(Ns) F
48、k 0; k j Figure 1 Accelerancebai/Fjm/(Ns2) kg1Fk 0; k j Figure 2 Dynamic compliancecxi/Fjm/N Fk 0; k j Figure 3 Comment Boundary conditions are easy to achieve experimentally. Term Symbol Unit Boundary conditions Blocked impedance Zij Fi/vjNs/m vk 0; k j Blocked effective mass Fi/ajNs2/m kg ak 0; k
49、j Dynamic stiffness Fi/xjN/m xk 0; k j Comment Boundary conditions are very difficult or impossible to achieve experimentally (see also A.2).Term Free impedance Effective mass (free effective mass) Free dynamic stiffness Symbol Unit Boundary conditions Fj/vi 1/YijNs/m Fk 0; k j Fj/aiNs2/m kg Fk 0; k j Fj/xiN/m Fk 0; k j Comment Boundary conditions are easy to achieve, but results shall be used with great caution in system modelling. aMobility is sometimes called mechanical adm
