1、BRITISH STANDARD BS 6794:1986 ISO 8002:1986 Method for Reporting measured vibration data for land vehicles ISO title: Mechanical vibrations Land vehicles Method for reporting measured data UDC 629.11.012.814:534.1.087BS6794:1986 This British Standard, having been prepared under the directionof the G
2、eneral Mechanical Engineering Standards Committee, was published under the authority ofthe Board of BSIand comes into effect on 28 November 1986 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference GME/21 Draft for comment 84/77504 DC ISBN 0 580 15499 8 C
3、ommittees responsible for this British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Committee (GME/-) to Technical Committee GME/21, upon which the following bodies were represented: British Internal Combustion Engine Manufacturers A
4、ssociation British Ship Research Association British Steel Corporation Department of Trade and Industry (National EngineeringLaboratory) Electricity Supply Industry in England and Wales Engineering Equipment and Materials Users Association Institute of Sound and Vibration Research Institution of Ele
5、ctronic and Radio Engineers Institution of Mechanical Engineers Ministry of Defence Motor Industry Research Association Power Generation Association (BEAMA Ltd.) Society of British Aerospace Companies Limited Society of Environmental Engineers United Kingdom Atomic Energy Authority Amendments issued
6、 since publication Amd. No. Date of issue CommentsBS6794:1986 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope 1 2 Field of application 1 3 References 1 4 Definitions 1 5 Symbols and subscripts 2 6 Uniform method of reporting 2 7 Mea
7、sured data 3 8 Parameters of analysis 3 9 Test conditions 4 Annex A Example method of reporting 6 Figure 1 Test site 6 Figure 2 Power spectral density curve 8 Figure 3 Zero-mean probability density curve normalized to the r.m.s. value 9 Figure 4 Power spectral density curve 10 Table 1 2 Table 2 6 Ta
8、ble 3 7 Publications referred to Inside back coverBS6794:1986 ii BSI 12-1999 National foreword This British Standard has been prepared under the direction of the General Mechanical Engineering Standards Committee. It is identical with ISO8002:1986 “Mechanical vibrations Land vehicles Method for repo
9、rting measured data” which was prepared by Technical Committee ISO/TC 108 of the International Organization for Standardization (ISO) and in the development of which the UK played an active part. Terminology and conventions. The text of the International Standard has been approved as suitable for pu
10、blication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full p
11、oint on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. ISO 4865, to which reference is made in the text, is currently in preparation, and until it is published, terminology given in ISO 20
12、41 should be sufficient for the purposes of this standard. The Technical Committee has reviewed the provisions of ISO 2041, ISO 2631 and ISO 5349, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A related British Standard to
13、 ISO 2041 is BS 3015:1976 “Glossary of terms relating to mechanical vibration and shock”. Two further British Standards related to ISO 2631 and ISO 5349 are currently in preparation. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards
14、 are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO 5008:1979 BS 6055:1981 Methods for measurement of whole-body vibration of the opera
15、tors of agricultural wheeled tractors and machinery (Identical) IEC Publication 225:1966 BS 2475:1964 Octave and one-third octave band-pass filters (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 10, an inside back cov
16、er and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6794:1986 BSI 12-1999 1 0 Introduction It is often useful to compare and/or to compile measured vibration data
17、from various sources. These endeavours are more difficult when the data are presented in different forms, such as constant bandwidth r.m.s. curves (of various bandwidths), proportional bandwidth curves, or power spectral density (PSD) curves, sometimes on linear scales and sometimes on logarithmic s
18、cales. Tedious and time-consuming mathematical transformation and replotting are therefore necessary, and this introduces the risk of errors. This International Standard specifies, a uniform method for reporting data to facilitate comparing and compiling data. The results of a measurement of random
19、vibration are an estimate based on a sample. This International Standard specifies the analysis parameters to be reported so that the statistical precision of the reported data can be determined. The measured vibration on land vehicles is a function both of the vehicle and of external factors, such
20、as the operating conditions and the road or terrain profile. For work machines, the operating conditions are the machine work cycle and may vary considerably between segments of a specific work cycle. This International Standard specifies the reporting of the operating conditions, of the road or ter
21、rain conditions and of the work cycle (for work machines) as related to the reported vibration data. This information is necessary to assess and to compare data. This International Standard emphasizes the need to include most of the relevant information on the curves or tables of results. The intent
22、 is to encourage putting details and results in a complete form on a few pages. This will facilitate compiling and comparing data and will facilitate international use of the data because the amount of translation necessary to identify the data will be reduced. The purpose of this International Stan
23、dard is to specify complete and uniform reporting of parameters, methods and results. It is not the purpose of this International Standard to specify any particular method to be used in the work itself. An example which meets the minimum requirements of this International Standard is given in the an
24、nex. 1 Scope This International Standard specifies a uniform method for reporting measured vibration data for all forms of land vehicles and work machines. 2 Field of application This International Standard applies to reporting data to be used for certain types of structural testing of land vehicles
25、 and work machines or their components and to reporting data on vibration measured at the vehicle-occupant interface. This International Standard applies to original reports of measured data and to reports or other publications which assess, summarize, compare or compile measured data from original
26、reports. It is not applicable to the reporting of any form of transfer function or other dynamic property of a system as derived from the measured data. 3 References ISO 2041, Vibration and shock Vocabulary. ISO 2631, Evaluation of human exposure to whole-body vibration. ISO 4865, Vibration and shoc
27、k Methods for analysis and presentation of data 1) . ISO 5008, Agricultural wheeled tractors and field machinery Measurement of whole-body vibration to the operator. ISO 5349, Guidelines for the measurement and the assessment of human exposure to hand-transmitted vibration. IEC Publication 225, Octa
28、ve, half-octave and third-octave band filters intended for the analysis of sounds and vibrations. 4 Definitions For the purposes of this International Standard, the terminology given in ISO 2041 and ISO4865, and the following definitions apply. 4.1 detrending any time domain process to reduce or rem
29、ove frequency components the period of which is longer than the record length 4.2 land vehicle a self-propelled device for carrying passengers, goods, or equipment, for example, car, bus, highway truck or train 4.3 magnitude window the incremental range of magnitude of the time history, as used to c
30、alculate the probability functions (magnitude distributions) of vibration data 1) At present at the stage of draft.BS6794:1986 2 BSI 12-1999 4.4 work machine a self-propelled or mobile device designed to alter or transmit energy and force for the performance of useful work, for example, tractor, loa
31、der, grader, ditcher or combine. Also a self-propelled device designed for carrying goods, material, or equipment on a work site, for example, dumper or fork-lift truck 5 Symbols and subscripts 5.1 Symbols 5.2 Subscripts x, y, z These lower case subscripts refer to the direction of rectilinear vibra
32、tions. For vehicle-occupant interface vibration, these shall be stated in accordance with ISO 2631 and ISO 5349. For vehicle or vehicle component vibration, a xis the fore-and-aft direction of vehicle motion, a yis the side-to-side direction, and a zis the vertical direction. If it is necessary to d
33、enote the positive direction of vehicle motion, it should be done in accordance with the relevant International Standards. 5.3 Subscripts rx, ry, rz These lower case subscript pairs refer to rotational vibrations about the x, y and z axes, i.e. roll, pitch and yaw. 5.4 Subscript capital letters Subs
34、cript capital letters refer to the location of the measurements. 6 Uniform method of reporting 6.1 Reporting of spectral data Curves or tables of spectral data shall conform to Table 1. For curves or tables of spectral data, the information stated on the curve sheet or table sheet shall include that
35、 given in 7.1, 7.2, 7.3, 8.1 c), 8.1 d), 8.1 e), 9.2 a), 9.2 b), 9.2 c), 9.2 e), 9.3 a) and 9.3 b). 6.2 Reporting of magnitude distribution data Magnitude distribution data shall be reported as zero-mean probability density curves of the instantaneous values of the acceleration, normalized to the r.
36、m.s. value. The curves shall be on logarithmic scales for probability density and linear scales for standard deviation (that is, a semi-logarithmic plot with logarithmic ordinates and linear abscissae). The abscissae shall also include a secondary scale in metres per second squared. The analysed dat
37、a shall be plotted at the centre of the magnitude window. The Gaussian probability density function shall be included on the curve sheet for reference purposes. NOTE 1A standard Gaussian probability density function can be shown if the data is analysed with a magnitude window width of0,5 standard de
38、viations or smaller. For larger magnitude window widths, Gaussian probability density values should be calculated and shown for the magnitude window width used in the data analysis. NOTE 2In some cases, the data may be adequately presented as the cumulative probability distribution as an alternative
39、 to the probability density. If cumulative probability distribution data are presented, it should be for the zero-mean instantaneous values of the acceleration, normalized to the r.m.s. value. Cumulative probability distribution data should be plotted on normal probability graph paper with the Gauss
40、ian straight line shown as a reference. Table 1 a Acceleration (m/s 2 ) B Bandwidth of a filter (Hz) g Acceleration due to gravity (m/s 2 ) T Total time of analysed data (s) W Magnitude window width used in the calculation of probability density, as a proportion of the r.m.s. of the data. Type of da
41、ta Form Scale Vehicle-occupant interface: Whole-body Third-octave bandwidth r.m.s. acceleration (unweighted) versus frequency (in conformity with ISO 2631) Logarithmic on both axes Hand Octave or third-octave bandwidth r.m.s. acceleration (unweighted) versus frequency (in conformity with ISO 5349) L
42、ogarithmic on bothaxes All other Acceleration power spectral density (PSD) versusfrequency Linear on both axes Seethe note NOTEAcceleration power spectral density may be plotted on logarithmic scales on both axes if the data range is so large as to make linear scales impractical. Logarithmic scales
43、are usually used to present data analysed by proportional bandwidths.BS6794:1986 BSI 12-1999 3 For curves or tables of magnitude distribution data, the information stated on the curve sheet or table sheet shall include that given in 7.1, 7.2, 7.3, 8.4, 9.2 a), 9.2 b), 9.2 c), 9.2 e), 9.3 a) and 9.3
44、b). 6.3 Reporting of measured or compiled data The reporting of measured or compiled data shall include the information specified in clauses 7, 8 and9, except as indicated in those clauses. Symbols used to designate the information shall be in accordance with clause 5. NOTEThe following clauses spec
45、ify the minimum information to be reported and should not be construed to limit reports to the required minimum. 7 Measured data 7.1 The location of the measurement point on the vehicle and the direction of the sensitive axis of the transducer shall be clearly stated. The location of the measurement
46、 point shall be referenced, by dimensions, to the standard coordinate system as specified in the relevant International Standards for the particular type of vehicle or machine concerned. If no such standard exists, the location shall be referenced, by dimensions, to the centre of an identified axle.
47、 7.2 The total r.m.s. acceleration of the reduced data, calculated from the time domain and extending over the same frequency range as the spectral data, shall be reported. NOTEThe reason for reporting the total r.m.s. acceleration, calculated from the time domain, is that this provides a cross-chec
48、k of the spectral data. The total r.m.s. acceleration in the time domain should be equal to that in the frequency domain. If the values are significantly different, there is an error in the analysis, such as wrong scaling, wrong correction factor for the sampling window function, or program errors.
49、The comparison of the total r.m.s. acceleration in the time domain to that in the frequency domain requires that both be calculated over the same frequency range. Therefore, the value in the time domain should be calculated from the data remaining after trends have been removed. A difference in values between the time domain and frequency domain can occur if the first few frequency channels are disregarded because of the difficulty in regulating the zero of the measurement chain. However, usually this difference will be small because if the values near 0 H
