ISA RP37 2-1982 Guide for Specifications and Tests for Piezoelectric Acceleration Transducers for Aerospace Testing《航空测试用压电式加速度传感器的规范和试验指南》.pdf

1、Guide for Specificationsand Tests for PiezoelectricAcceleration Transducersfor Aerospace TestingReaffirmed 29 September 1995ISARP37.21982 (R1995)RECOMMENDED PRACTICEISA The Instrumentation,Systems, andAutomation Society TMCopyright 1982 by the Instrument Society of America. All rights reserved. Prin

2、ted in the UnitedStates of America. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted in any form or by any means (electronic, mechanical, photocopying, recording, orotherwise), without the prior written permission of the publisher.ISA67 Alexander DriveP.O. B

3、ox 12277Research Triangle Park, North Carolina 27709ISARP37.21982 (R1995) Guide for Specifications and Tests for Piezoelectric Acceleration Transducers for Aerospace TestingISBN 0-87664-377-2ISA-RP37.2-1982 (R1995) 3PrefaceThis preface, as well as all footnotes and annexes, is included for informati

4、onal purposes and is not part of ISA-RP37.2-1982 (R1995).This recommended practice has been prepared as a part of the service of ISA, the international society for measurement and control, toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be s

5、tatic, but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms, and asks that they be addressed to the Secretary, Standards and Practices Board; ISA; 67 Alexander Drive; P.O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fa

6、x: (919) 549-8288; E-mail: standardsisa.org.The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards, recommended practices

7、, and technical reports. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce

8、SI-acceptable metric units in all new and revised standards to the greatest extent possible. The Metric Practice Guide, which has been published by the Institute of Electrical and Electronics Engineers as ANSI/IEEE Std. 268-1992, and future revisions, will be the reference guide for definitions, sym

9、bols, abbreviations,and conversion factors.CAUTION: The information presented within this ISA recommended practice is believed to be accurate and reflects the current state of knowledge within the field. The information is an interpretation and condensation of a larger volume of literature and exper

10、ience, some of which is contradictory and speculative. Therefore, application of the information to particular situations requires the exercise of the independent professional judgment of the user. ISA is not responsible for any results from such use of the information and shall not be liable for an

11、y damages caused by such use.It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards-making process by an individual in no way c

12、onstitutes endorsement by the employer of that individual, of ISA, or of any of the standards, recommended practices, and technical reports that ISA develops.The development of this recommended practice was initiated as a result of a survey conducted in December 1960. A total of 240 questionnaires w

13、as sent out to transducer users and manufacturers in the aerospace field. In their replies, a strong majority indicated a need for standardization of specifications and tests of several types of commonly used aerospace test transducers with electrical output.On the basis of these replies, a Project

14、Sub-Committee 8A-RP37.2, Guide for Piezoelectric Acceleration Transducers for Aerospace Testing, was formed under the cognizance of Committee 8A-RP37, Transducers for Aerospace Testing, of the Aerospace Standards Group, and this recommended practice was developed.4 ISA-RP37.2-1982 (R1995)The followi

15、ng individuals served as members of Subcommittee 8A-RP37.2:NAME COMPANYT. A. Perls, Chairman Lockheed Missiles state thread size, class, mounting torque, and temperature rating, if applicable.)xxTemperature Range,Operating x 6.2Storage xTransducer Capacitance with Stated Cablex 5.3.3Transducer Seal

16、x 5.3.1 6.11Transduction ElementMaterial Type (proprietary name acceptable)xSensing Mode* xMechanical Isolation* xWeight (state whether cable or other accessories are included)xxISA-RP37.2-1982 (R1995) 134.2 Performance characteristicsBasic Supple-mentalCharacteristics Determined During:Individual A

17、ccep. Tests Qual. TestsWithin Stated TolerancesMeasured ValueAcceleration Limit*Defined in 4.3xAcceleration Range* x 6.5.1Amplification Factor at Resonant Frequency*x 6.3.1Amplitude LinearityShock* x 6.5.2Vibration* x 6.5.1Partial Range x xEnvironmental EffectsAcoustic Sensitivity* x 6.9Electromagne

18、tic Response x 6.10Temperature Sensitivity Error*65F to 350F (177C) or x 6.7Above 350 F. x 5.4.1Below 65F. x 5.4.1Transient Temperature Error* x 6.8Other x 6.12Frequency, Resonant, Mounted; Nominal (and tolerance), or Minimumx63Frequency Response*Maximum Range x 6.4Stated Partial Range x 5.2.2Mounti

19、ng Error x 6.1Polarity* x 5.3.4Reference Sensitivity, Charge or Voltage,Nominal (and tolerance)*x 5.2.1Sensitivity Stability x 6.13Strain Sensitivity x 6.6Transverse Sensitivity*At Stated Single Freq. x 5.2.3Over Maximum Freq. Range x 5.2.314 ISA-RP37.2-1982 (R1995)4.3 Additional terminology(For ter

20、ms not defined here, see ISA-S37.1.)4.3.1 acceleration limit: the maximum vibration and shock acceleration which the transducer can accept in either direction along its sensitive axis without permanent damage, usually stated as _gs. The acceleration limits are usually much wider than the Acceleratio

21、n Range and thereby represent a measure of the overload capability of the transducer.4.3.2 acceleration range: the range of accelerations over which the transducer has the specified linearity.4.3.3 acoustic sensitivity: the output of a transducer (not due to rigid body motions) in response to a spec

22、ified acoustical environment. This is sometimes expressed as the acceleration in g rms sufficient to produce the same output as induced by a specified sound pressure level spectrum having an overall value of 140 db referred to 0.0002 dyne per sq. cm. rms.4.3.4 amplification factor at resonant freque

23、ncy: the ratio of the maximum sensitivity of a transducer (at its resonant frequency to its Reference Sensitivity).NOTE “Amplification factor at resonant frequency“ is sometimes referred to as “Q.“4.3.5 amplitude linearity, shock: closeness of sensitivity to reference sensitivity over a stated range

24、 of acceleration amplitudes, under shock conditions, usually specified as “within _percent for acceleration rise times longer than _ microseconds.“4.3.6 amplitude linearity, vibration: closeness of sensitivity over a stated range of acceleration amplitudes, at a stated fixed frequency, usually speci

25、fied as “within _percent.“4.3.7 electromagnetic field sensitivity: the maximum output of a transducer in response to a specified amplitude and frequency of magnetic field, usually expressed in gauss equivalent to a stated fraction of 1 g.4.3.8 frequency response: the change with frequency of the sen

26、sitivity with respect to the reference sensitivity, for a sinusoidally varying acceleration applied to a transducer within a stated range of frequencies, usually specified as “within _ percent of the reference sensitivity from _ to _ cps.“ The applicable total capacitance and load resistance should

27、be stated.4.3.9 grounded or ungrounded: refers to the presence or absence of an electrical connection between the “low“ side of the transducer element and the portion of the transducer intended to be in contact with the test structure. Method of ungrounding should be stated as “internally ungrounded

28、“ or “by means of separate stud.“4.3.10 markings: information shown on the transducer itself, will normally include Manufacturer, Model Number and Serial Number.4.3.11 mechanical isolation of transduction element: internal construction of transducer which allows forces (particularly bending forces a

29、nd external pressures) to be applied to the transducer case with negligible resulting forces on the transducer element.4.3.12 polarity: the relationship between the transducer output and the direction of the applied acceleration; taken as “standard“ when a positive charge or voltage appears on the “

30、high“ side of the transducer for an acceleration directed from the mounting surface into the body of the accelerometer.ISA-RP37.2-1982 (R1995) 154.3.13 reference sensitivity (charge or voltage): the ratio of the change in charge or voltage generated by a transducer to the change in value of the acce

31、leration that is measured under a set of defined conditions (amplitude, frequency, temperature, total capacitance, amplifier input resistance, mounting torque). Deviations in sensitivity should be reported as deviations from the reference sensitivity.4.3.14 sensing mode of transduction element: the

32、method used to stress the transduction element such as compression, bending or shear.4.3.15 sensitivity: the ratio of the change in transducer output to a change in the value of the acceleration.NOTES1. Where one sensitivity under defined conditions is the basis for determining deviations in perform

33、ance, use “reference sensitivity.“2. Because the use of piezoelectric acceleration transducers for the measurement of both shock and vibration, the acceleration is required to be known in either g peak or g rms. A specified sensitivity in millivolts per g is to be understood as meaning “rms millivol

34、ts per rms g“ or its equivalent “peak millivolts per peak g.“ The use of “mixed units“ such as rms millivolts per peak is to be avoided. Note, however, that an output of 10 millivolts rms is also approximately 14.1 millivolts peak, and an acceleration of 1 g rms is approximately 1.41 g peak and, the

35、refore,4.3.16 shock: a substantial disturbance characterized by a rise and decay of acceleration from a constant value in a short period of time.4.3.17 strain sensitivity: the sensitivity to strains applied to the base by bending, in the absence of any rigid body motion of the transducer. It is expr

36、essed as 10-6 times the equivalent acceleration level in gs for a strain in the plane of the base.4.3.18 temperature range, operating: the interval of temperatures in which the transducer is intended to be used, specified by the limits of this interval.4.3.19 temperature sensitivity error: the chang

37、e in sensitivity of a transducer from its reference sensitivity as a result of changes in its ambient temperature over a specified operating temperature range.NOTE If changes in voltage sensitivity are specified, the total associated capacitance must be stated.4.3.20 transient temperature error: the

38、 output of a transducer as a result of a specified transient temperature change within a specified operating temperature range. NOTE The associated capacitance and load resistance, as well as the time, after the applied transient, at which the amplitude peak occurs must be specified.4.3.21 transvers

39、e sensitivity: the maximum sensitivity of a uniaxial transducer to a transverse acceleration, within a specified frequency range, usually expressed in percent of the reference sensitivity in the intended measuring direction.10mvg-10mv rmsg rms-10mv pkg pk-7.07mv rmsg pk-14.1mv pkg rms-= =16 ISA-RP37

40、.2-1982 (R1995)5 Individual acceptance tests and calibrationTests are listed in the order they are to be performed.5.1 Visual inspectionConduct a complete visual examination for conformance to stated configuration and markings. Determine weight, dimensions, thread size, and class utilizing standard

41、inspection instruments. Check mating of accessory cable (if any) by attaching and removing the cable. Note any discrepancy.5.2 Initial functional tests5.2.1 Reference charge or voltage sensitivityFor most applications, it is recommended that the sensitivity of a transducer be determined by compariso

42、n with a standard calibrated transducer. This method is described in ANSI-S2.2-1959.The frequency of the driving signal should be in the range of 40 to 100 cycles per second and should be monitored continuously by a properly calibrated electronic counter.Charge sensitivity can be determined by multi

43、plying the voltage sensitivity in volts per g by the total capacitance of the system in pico-farads, providing charge sensitivity in pico-coulombs per g.A system consisting of a transducer, cable, and amplifier should be calibrated as a unit. The sensitivity will be that recorded at the output of th

44、e amplifier, in volts/g. Specifications should include transducer sensitivity with cable, capacitance, and amplifier gain.If a standard transducer with calibration traceable to NBS is not available, a reasonably dependable sensitivity can be determined by methods described in ANSI-S2.2-1959. The cha

45、tter method, described in the Kissinger reference, see Annex A, is the simplest to use and is the most dependable for reasonable accuracy.The temperature of the transducers should be measured and recorded.NOTES1. The standard transducer used should have a calibration traceable (see ISA-S37.1) to a c

46、alibration performed at the National Bureau of Standards within the normal calibration period of one year. The transducer used as a standard should be reserved for this purpose only; it should not be exposed to large values of shock, vibration or temperature extremes; and its calibration should be c

47、hecked periodically by either of the referenced methods.2. The surface on which each transducer is mounted and the part of the transducer base which touches that surface should be clean and flat, with a surface finish of 64 microinches or less. If oil or grease is used as a gasketing material, it sh

48、ould be clean, freshly applied to both surfaces just before the test, and completely removed immediately afterwards.3. The signal used to excite the motion of the transducers should be as nearly sinusoidal as possible. The wave shape of the output signal of both transducers should be observed freque

49、ntly throughout the test and no perceptible distortion should be allowed. Preferably, a distortion meter should be used, and the distortion kept below 3%.ISA-RP37.2-1982 (R1995) 174. Screw-attached transducers should be mounted with the torque recommended by the manufacturer, using a good grade torque wrench. A preliminary observation of the wave shape and amplitude on an oscilloscope should be made when the transducer is mounted with a torque about 10% less than recommen