BS-7935-2-2004.pdf
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1、BRITISH STANDARD BS 7935-2:2004 Constant amplitude force calibration Part 2: Calibration of the calibration device instrumentation to be used for the dynamic calibration of non-resonant uniaxial dynamic testing systems Method ICS 29.040 ? Licensed Copy: London South Bank University, London South Ban
2、k University, Fri Dec 08 10:57:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7935-2:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 September 2004 BSI 30 September 2004 The following BSI references relate to the work on this Britis
3、h Standard: Committee reference ISE/NFE/4 Draft for comment 04/19981143 DC ISBN 0 580 44479 1 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee ISE/NFE/4, Mechanical testing of materials, upon which the following bodies wer
4、e represented: GAMBICA Association Ltd. Network Rail Society of British Aerospace Companies Ltd. United Kingdom Accreditation Service University College London National Physical Laboratory Copper Development Association Railway Industry Association British Non-Ferrous Metals Federation UK Steel Asso
5、ciation Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:57:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7935-2:2004 BSI 30 September 2004 i Contents Page Committees responsibleInside front cover Fo
6、rewordii Introduction1 1Scope1 2Normative references1 3Terms and definitions1 4Principle1 5Apparatus2 6General requirements2 7Calibration procedure2 8Calculation of results3 9Calibration report4 Annex A Calibration frequency content5 Figure 1 AC calibration waveform3 Figure A.1 Example of 59 Hz load
7、 sinewave (measured signal)5 Figure A.2 Example of single cycle of 50 Hz load sinewave (measured signal)5 Figure A.3 Power spectral density of signal shown in Figure A.1 over the range DC to 2.5 KHz6 Figure A.4 Power spectral density of signal shown in Figure A.1 over the range DC to 500 Hz6 Table 1
8、 AC calibration waveforms3 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:57:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7935-2:2004 ii BSI 30 September 2004 Foreword This part of BS 7935 has been published under the authority of Technical Committee ISE
9、/NFE/4. It describes a method for performing the DC and AC calibration of calibration device instrumentation used in BS 7935-1. BS 7935-1 describes a method for determining the relationship between the true force range applied to a test-piece subject to constant amplitude uniaxial sinusoidal loading
10、 and the force range indicated by the testing system. This British Standard describes methods of performing the DC and AC calibration of calibration device instrumentation used in BS 7935-1. References to this standard should indicate that the methods used are in accordance with BS 7935-2. This publ
11、ication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cov
12、er, pages i and ii, pages 1 to 6, an inside back cover and a back cover. The BS I copyright notice displayed in this document indicates when the document was last issued. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:57:09 GMT+00:00 2006, Uncontrolled Copy,
13、 (c) BSI BS 7935-2:2004 BSI 30 September 2004 1 Introduction In a dynamic test, the true force experienced by the test-piece might differ significantly from the force indicated by the testing system. This error results from inertia force acting on the loadcell and any errors in the electronics of th
14、e dynamic force indicating system. Inertia forces equate to the grip mass (interposed between the loadcell and test-piece) multiplied by its local acceleration. Inertia forces depend on: a) the amplitude of motion; b) the frequency; c) the grip mass; d) the compliance of the test-piece; e) the confi
15、guration of the testing system e.g. frame compliance and type of mounting. BS 7935-1 describes two methods of measuring dynamic force errors on uniaxial test machines. Both of these methods requires that the calibration device instrumentation be calibrated in accordance with BS 7935-2. 1 Scope In or
16、der to perform a dynamic calibration of a uniaxial testing system it is necessary to measure the forces experienced by the test-piece to known levels of accuracy. This part of BS 7935 defines the calibration procedure for the calibration device instrumentation. The method for the analysis of the res
17、ults is also described, leading to a range of frequencies over which the instrumentation is valid for use with BS 7935-1. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undate
18、d references, the latest edition of the referenced document (including any amendments) applies. BS 7935-1, Constant amplitude dynamic force calibration Part 1: Calibration and verification of non-resonant uniaxial dynamic testing systems Method. 3 Terms and definitions For the purposes of this part
19、of BS 7935, the following terms and definitions apply. 3.1 calibration device replica test-piece or proving device 3.2 calibration device instrumentation conditioning electronics and display used in conjunction with calibration device 3.3 dynamic reference standard instrumentation providing traceabl
20、e 2 mV/V excitation voltage for calibration device instrumentation 4 Principle Generate a set of DC voltages using a dynamic reference standard. Determine the difference between the values displayed on the calibration device instrumentation and the nominal values generated by the dynamic reference s
21、tandard. Similarly, generate a set of AC waveforms using the dynamic reference standard in the range from DC to the maximum test frequency with varying amplitudes and offsets. The peak and trough values displayed on the calibration device instrumentation are compared with the nominal values generate
22、d by the dynamic reference standard. To simulate laboratory conditions, the AC calibration is repeated with a known amount of harmonic distortion to ensure the instrumentation is capable of measuring such peak and trough values correctly. Licensed Copy: London South Bank University, London South Ban
23、k University, Fri Dec 08 10:57:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7935-2:2004 2 BSI 30 September 2004 5 Apparatus 5.1 Calibration device instrumentation, supplies a DC excitation voltage (VE) to the calibration device, reads the output voltage from the calibration device, and digitally
24、 displays the ratio of this voltage to the excitation voltage (in mV/V). Where the calibration device output voltage is varying in a sinusoidal manner (due to a dynamic force being applied to the device), the instrumentation shall display the peak and trough values of this mV/V ratio. The resolution
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