1、BRITISH STANDARD BS 6955-13: 1994 ISO 5347-13: 1993 Calibration of vibration and shock pick-ups Part 13: Method of test for base strain sensitivity UDC 534.1:681.327.7:53.089.6BS6955-13:1994 This British Standard, having been prepared under the direction of the General Mechanical Engineering Standar
2、ds Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 March 1994 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference GME/21 Draft for comment 87/72304 DC ISBN 0 580 23085 6 Committees responsible for th
3、is British Standard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/21, upon which the following bodies were represented: Electricity Association Federation of Civil Engineering Contractors Imp
4、erial College of Science and Technology Institute of Sound and Vibration Research Institution of Mechanical Engineers Lloyds Register of Shipping Ministry of Defence Open University Power Generation Contractors Association (PGCA (BEAMA Ltd.) Railway Industry Association of Great Britain Sira Test an
5、d Certification Ltd. Society of British Aerospace Companies Limited The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Coal Corporation Health and Safety Executive Society of Environmental Engineers University of Cranfield Amendments
6、 issued since publication Amd. No. Date CommentsBS6955-13:1994 BSI 09-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Apparatus 1 3 Method 1BS6955-13:1994 ii BSI 09-1999 National foreword This Part of BS6955 has been prepared under the direction of the
7、 General Mechanical Engineering Standards Policy Committee. It is identical with ISO5347-13:1993 Methods for the calibration of vibration and shock pick-ups Part13: Testing of base strain sensitivity, published by the International Organization for Standardization (ISO). ISO 5347-13 was prepared by
8、Technical Committee ISO/TC108, Mechanical vibration and shock, in which the UK played an active part. BS 6955 consists of the following Parts, which are identical with the corresponding Parts of ISO5347: Part 0: Guide to basic principles; Part 1: Methods for primary vibration calibration by laser in
9、terferometry; Part 2: Method for primary shock calibration by light cutting; Part 3: Method for secondary vibration calibration; Part 4: Method for secondary shock calibration; Part 5: Method for calibration by Earths gravitation; Part 6: Method for primary vibration calibration at low frequencies;
10、Part 7: Methods for primary calibration by centrifuge; Part 8: Method for primary calibration by dual centrifuge; Part 9: Method for secondary vibration calibration by comparison of phase angles; Part 10: Method for primary calibration by high impact shocks; Part 11: Method of test for transverse vi
11、bration sensitivity; Part 12: Method of test for transverse shock sensitivity; Part 13: Method of test for base strain sensitivity; Part 14: Method of test for resonance frequency of undamped accelerometers on a steel block; Part 15: Method of test for acoustic sensitivity; Part 16: Method of test f
12、or mounting torque sensitivity; Part 17: Method of test for fixed temperature sensitivity; Part 18: Method of test for transient temperature sensitivity; Part 19: Method of test for magnetic field sensitivity. Part 20 of ISO 5347 is in preparation. It is envisaged that when it is published it will b
13、e implemented as Part20 of BS6955. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summar
14、y of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 and 2 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.BS6955-13:1994
15、 BSI 09-1999 1 1 Scope ISO 5347 comprises a series of documents dealing with methods for the calibration of vibration and shock pick-ups. This part of ISO5347 lays down detailed specifications for the instrumentation and procedure to be used for base strain sensitivity testing. It applies to rectili
16、near accelerometers, mainly of the piezoelectric type. This part of ISO5347 is applicable for the following parameters: a) Reference values: pick-up base radius of curvature:25m base strain:2,5 10 4 b) Check values: radius of curvature62,5m, strain of base1 10 4 radius of curvature12,5m, strain of b
17、ase5 10 4 2 Apparatus 2.1 Equipment capable of maintaining room temperature at23 C 3 C. 2.2 Cantilever beam, designed so that it can produce the range of radii of curvature and base strains specified inclause1. The beam shall have its bending plane horizontally. The surface to which the pick-up is c
18、onnected shall be ground so as to have a roughness value, as the arithmetical mean deviation, R a , of less than14m. The flatness shall be such that the surface is contained between two parallel planes at a distance apart of54m. The drilled and tapped holes for connecting the pick-up shall have a pe
19、rpendicularly tolerance to the surface of less than104m, i.e.the centreline of the hole shall be contained in a cylindrical zone of104m in diameter and a height equal to the hole depth. A steel beam clamped into a rigid support at one end is recommended. The test location is40mm from the clamped end
20、, where the area is12,5mm 0,1mm thick and76mm 0,5mm wide. No requirements are specified as regards the rest of the beam, but a length of1,5m is convenient. On both sides of the test pick-up, strain gauges can be bonded. It is recommended to apply a force slowly at a known distance, measured with an
21、error of 1mm, from the test location instead of measuring strain. If this gives too low a frequency, it is recommended that the beam be deflected and then be allowed to vibrate freely. The force and the cantilever beam measures can be calculated from the following formulae: where 2.3 Pick-up amplifi
22、er, low frequency type, for piezoaccelerometer charge amplifiers. 2.4 Low frequency measuring instrumentation, with uncertainty maximum1% of reading. 2.5 Strain gauges, power supply, amplifier and recorder (optional). 2.6 Force-measuring equipment (optional), covering the range from0to100N and with
23、uncertainty maximum 2% of reading. 3 Method 3.1 Test procedure Mount the beam for horizontal deflection. Apply forces slowly to the free end, in both directions, to give specified base strains to the transducer. If the application of these forces gives too low a frequency for the pick-up or its ampl
24、ifier, deflect the beam with a force to give a strain higher than the reference value. Then release the beam and allow it to vibrate freely on its resonance frequency, which is about5Hz. Measure the output from the pick-up and from the strain gauges on a recorder. F is the force applied at the free
25、end of the beam, in newtons; E is Youngs modulus, in newtons per square metre (for steel, E = 2,1 10 11N/M 2 ); is the strain; b is the beam width, in metres; h is the beam thickness, in metres; l is the distance from the test location to the force, in metres; R is the radius of curvature, in metres
26、.BS6955-13:1994 2 BSI 09-1999 Determine the maximum outputs from the pick-up and from the strain gauges, if any, for the three specified strains. Repeat the tests at four different pick-up directions. 3.2 Expression of results Calculate the strain sensitivity, S , in metres per second squared, from
27、the following formula: where a is the pick-up output, in metres per second squared; is the applied strain where2,510 4is the reference value. S ( a ( ( - =blankBS 6955-13: 1994 ISO 5347-13: 1993 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national b
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