1、BRITISH STANDARD BS 6955-22:1997ISO 5347-22:1997Methods forCalibration of vibration and shock pick-ups Part 22: Acceleration resonance testing General methodsICS 17.160CONFIRMED APRIL 2008BS 6955-22:1997This British Standard, having been prepared under the direction of the Engineering Sector Board,
2、was published underthe authority of the Standards Board and comes into effect on 15 June 1997 BSI 02-1999ISBN 0 580 27569 8National forewordThis British Standard reproduces verbatim ISO 5347-22:1997 and implements it as the UK national standard.The UK participation in its preparation was entrusted t
3、o Technical Committee GME/21, Mechanical vibration and shock, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor r
4、elated international and European developments and promulgate them in the UK.A list of organizations represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may
5、 be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or using the “Find” facility of the BSI Standards Electronic Catalogue.A British Standard does not purport to include all the necessary provisions of a contract. Users of British Stand
6、ards are responsible for their correct application.Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, pages i and ii, the ISO title page, page ii, pages 1 to 3 and a back cover.Thi
7、s 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.Amendments issued since publicationAmd. No. Date CommentsBS 6955-22:1997 BSI 02-1999 iContentsPageNational foreword Inside front coverFor
8、eword ii1Scope 12Normative reference 13Apparatus 14Procedure 2Figure 1 Accelerometer transverse resonance frequency testing 2Figure 2 Accelerometer resonance frequency testing 3ii blankBS 6955-22:1997ii BSI 02-1999ForewordISO (the International Organization for Standardization) is a worldwide federa
9、tion of national standards bodies (ISO member bodies). The work of 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 committ
10、ee. International organizations, governmental and non-governmental, 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.Draft International Standards adopted by the techn
11、ical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote.International Standard ISO 5347-22 was prepared by Technical Committee ISO/TC 108, Mechanical vibration and shock, Subcommitte
12、e SC3, Use and calibration of vibration and shock measuring instruments.ISO 5347 consists of the following parts, under the general title Methods for the calibration of vibration and shock pick-ups: Part 0: Basic concepts; Part 1: Primary vibration calibration by laser interferometry; Part 2: Primar
13、y shock calibration by light cutting; Part 3: Secondary vibration calibration; Part 4: Secondary shock calibration; Part 5: Calibration by Earths gravitation; Part 6: Primary vibration calibration at low frequencies; Part 7: Primary calibration by centrifuge; Part 8: Primary calibration by dual cent
14、rifuge; Part 9: Secondary vibration calibration by comparison of phase angles; Part 10: Primary calibration by high impact shocks; Part 11: Testing of transverse vibration sensitivity; Part 12: Testing of transverse shock sensitivity; Part 13: Testing of base strain sensitivity; Part 14: Resonance f
15、requency testing of undamped accelerometers on a steel block; Part 15: Testing of acoustic sensitivity; Part 16: Testing of mounting torque sensitivity; Part 17: Testing of fixed temperature sensitivity; Part 18: Testing of transient temperature sensitivity; Part 19: Testing of magnetic field sensit
16、ivity; Part 20: Primary vibration calibration by the reciprocity method; Part 21: Shock calibration using laser Doppler velocimeter; Part 22: Accelerometer resonance testing General methods.Descriptors: Vibration, mechanical shock, measurement, measuring instruments, accelerometers, sensors, calibra
17、tion.BS 6955-22:1997 BSI 02-1999 11 ScopeISO 5347 comprises a series of documents dealing with methods for the calibration of vibration and shock pick-ups.This part of ISO 5347 lays down detailed specifications for the instrumentation and procedures to be used for accelerometer resonance testing. It
18、 applies to rectilinear accelerometers of the piezoresistive, piezoelectric and variable capacitance types in the frequency range50Hz to 200 kHz.The procedures are in general contrary to those described in ISO 5347-14 which is limited to undamped accelerometers. The frequency response of a piezoelec
19、tric accelerometer depends on the value of the (lowest) resonance frequency of the instrument when mounted on the structure to be tested. It does not appear possible to specify a test which will determine this frequency for all installations of a given accelerometer. This procedure gives the acceler
20、ometer resonance frequency under a set of standard reproducible conditions, with the understanding that the resonance frequency in actual use will in all probability be appreciably different (generally lower, by a factor depending on the mass and compliance of the test structure and the method of at
21、tachment). The procedure is not suitable for evaluating the mounted resonance frequency for a field of application; a suitable method is given in ISO 5348.2 Normative referenceThe following standard contains provisions which, through reference in this text, constitute provisions of this part of ISO5
22、347. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of ISO 5347 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO
23、maintain registers of currently valid International Standards.ISO 5348:1), Mechanical vibration and shock Mechanical mounting of accelerometers. 3 Apparatus3.1 Equipment capable of maintaining room temperature at 23 C 3C.3.2 Frequency generator and indicator, having a frequency range of 50 Hz to 200
24、 kHz.3.3 Power amplifier vibrator combination, having a frequency range of 50 Hz to 200 kHz.3.4 Oscilloscope, having a frequency range of 50 Hz to 200 kHz.3.5 Vibrator and reference accelerometer, having a resonance frequency greater than 50 kHz.3.6 Analysing equipment, having a frequency range of l
25、ess than 10 MHz.3.7 Reference block, a steel block28mm28 mm 28 mm, having a mass of about 180 g, for resonance frequencies up to 50 kHz. A beryllium block of the same dimensions shall be used for resonance frequencies up to 100 kHz. For frequencies above 100 kHz a beryllium rod having a diameter of
26、14 mm and 400 mm long, may be used. One ground surface of the block, and one end of the rod, which shall be used for mounting the accelerometer shall have a surface roughness value (expressed as the arithmetical mean deviation) R a , of less than 1m.The flatness of the ground surface shall be such t
27、hat the surface is constrained between two parallel planes at a distance apart of5m.The drilled and tapped holes for connecting the transducer shall have a perpendicularity tolerance to the surface of less than 0,5.3.8 Transverse test block, a beryllium block 28 mm 28mm28 mm with four ground surface
28、s, each of which shall have a roughness value, expressed as the arithmetical mean deviation R a , of less than 1m.The flatness of the ground surfaces shall be such that the surface can be constrained between two parallel planes at a distance apart of 5m.The drilled and tapped holes for connecting th
29、e transducer and accessories shall have a perpendicularity tolerance to the surface of less than 0,5.This test accelerometer shall be mounted on one ground side of this block. A mass identical to the accelerometer mass shall be symmetrically mounted in the opposite side for counterbalance (see Figur
30、e 1). 1) To be published. (Revision of ISO 5348:1987)BS 6955-22:19972 BSI 02-19994 Procedure4.1 MountingThe testing shall be carried out under well-defined conditions in accordance with ISO 5348.The accelerometer and its accessories shall be mounted according to the manufacturers recommendations.4.2
31、 Mounted resonance frequency, sinusoidal vibrator methodMeasure the accelerometer output using the comparison method throughout the frequency range including and above the resonance frequency of the accelerometer. The resonance frequency is the frequency of maximum sensitivity. The phase angle relat
32、ive to the standard accelerometer changes by about 180 in the range of frequencies near the resonance frequency of the accelerometer. There may be minor or local resonances detected where the phase angle changes to about 90 but returns to 0 at a slightly higher frequency. Report these frequencies as
33、 local resonances where minor increases in sensitivity are detected.The standard accelerometer with known resonance frequencies should be built into the vibrator armature (see Figure 2). The resonance frequency of the vibrator is determined by measuring the transfer function between the drive coil c
34、urrent and the standard accelerometer output. Use the vibrator only throughout the range up to 95 % of its moving parts including accelerometer resonance frequency.NOTE The low-frequency suspension and rigid-body rise in amplitude and change in phase may be ignored.The resonance frequency of the vib
35、rator armature may also be determined with an accelerometer whose damped natural frequency has been determined by the shock method and found to be above the vibrator resonance frequency.Damped natural frequency of accelerometers may be determined by comparison of the phase angle. The frequency where
36、90 phase shift is detected is defined as the damped natural frequency. This measurement is typically used for accelerometer with damping ratios equal to, or greater than, about 0,7.4.3 Mounted cross axis resonance frequencyThe mounted cross axis resonance frequency may be determined using the same v
37、ibrator as in 4.2. The accelerometer mounted on the transverse test block described in 3.8 shall be mounted on the vibrator with the accelerometers sensitive axis perpendicular to the axis of vibration. Two additional accelerometers shall be mounted on the transverse test block to determine that the
38、 entire vibrator, block, accelerometer structure is moving uniaxially. The two accelerometers should be in phase to ensure that the assembly is not rotating. Rotation would result in a false transverse resonance frequency.NOTE Alternatively, laser interferometric vibration sensors may be used to det
39、ect such rotational or differential velocity components, these are advantageous (non-contact) load-free measurement. True differential laser vibrometers generate the difference signal within the optical system and therefore do not encounter the matching problems suffered by pairs of individual senso
40、rs.Figure 1 Accelerometer transverse resonance frequency testingBS 6955-22:1997 BSI 02-1999 3The accelerometer under test should be rotated in 30 intervals over 90 to determine the maximum response and lowest resonance frequency (see Figure 1).4.4 Mounted damped natural frequency, shock methodThe ac
41、celerometer is mounted on the block or rod described in 3.7. This assembly shall be supported by a soft elastic suspension.The damped natural frequency of the accelerometer shall be determined by mechanical excitation due to a short transient shock pulse whose pulse duration is about three times the
42、 natural period of the accelerometer. If the transient shock pulse is generated by an impact the rise time will decrease with decreasing contact area of the impact tool or hammer. For frequencies greater than 300 kHz, short rise time shock pulses shall be generated by fracture of a glass or lead rod
43、 on the end surface of the rod.The output of the accelerometer shall be captured in memory through an analogue-to-digital convertor or on a storage oscilloscope whose sampling rate shall not be less than two times the resonance frequency of the accelerometer. The frequency response of all electronic
44、 equipment must be adequate for fidelity of accelerometer output at these high frequencies.An analysis of the transducer output will indicate the frequency with highest output. This frequency is the natural damped resonance of the accelerometer. There may be other frequencies where a significant inc
45、rease in accelerometer output is observed. If these output levels are less than 50 % of the output at the natural damped resonance frequency the frequencies at which these lower output levels are observed shall be reported as local or minor resonances.Figure 2 Accelerometer resonance frequency testi
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