BS EN 13477-1-2001 Non-destructive testing - Acoustic emission - Equipment characterization - Equipment description《无损检验 声发散 设备特性 设备描述》.pdf

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1、BRITISH STANDARD BS EN 13477-1:2001 Non-destructive testing Acoustic emission Equipment characterization Part 1: Equipment description The European Standard 13477-1:2001 has the status of a British Standard ICS 17.140.01; 19.100 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWB

2、S EN 13477-1:2001 This British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 March 2001 BSI 03-2001 ISBN 0 580 36956 0 National foreword This British Standard is the off

3、icial English language version of EN 13477-1:2001. The UK participation in its preparation was entrusted to Technical Committee WEE/46, Non-destructive testing, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-r

4、eferences The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic C

5、atalogue. 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. aid enquirers to understand the

6、 text; present to the responsible European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an ins

7、ide front cover, the EN title page, pages 2 to 9 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 13477-1 January 2001 ICS 19

8、.100 English version Non-destructive testing Acoustic emission Equipment characterization Part 1: Equipment description Essais non destructifs Emission acoustique Caractrisation de lquipement Partie 1: Description de lquipement Zerstrungsfreie Prfung Schallemissionsprfung Gertecharakterisierung Teil

9、 1: Gertebeschreibung This European Standard was approved by CEN on 28 December 2000. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists

10、and bibliographical references concerning such national standards may be obtained on application to the Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibi

11、lity of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherland

12、s, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2001 CEN All rights of exploitation in any form and by any means reserved wo

13、rldwide for CEN national Members. Ref. No. EN 13477-1:2001 EPage 2 EN 13477-1:2001 BSI 03-2001 Contents Page Foreword. 3 1 Scope . 4 2 Normative references . 4 3 Terms and definitions. 4 4 Detection 4 4.1 Sensing element 5 4.2 Sensor case . 5 4.3 Sensor characteristics 5 5 Signal conditioning. 6 5.1

14、 Preamplifier 6 5.2 Cables 6 5.3 Post-amplification and frequency filtering 7 6 Signal measurement. 7 6.1 Continuous signal. 7 6.2 Burst signal 7 6.3 Waveform. 8 7 Analysis and output of results. 8 8 Automated system 9 8.1 Automated analysis 9 8.2 Feedback to a control or alarm system 9Page 3 EN 134

15、77-1:2001 BSI 03-2001 Foreword This European Standard has been prepared by Technical Committee CEN/TC 138, Non-destructive testing, the Secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by end

16、orsement, at the latest by July 2001, and conflicting national standards shall be withdrawn at the latest by July 2001. This European Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. This European Standard is considered to be

17、 a supporting standard to those application and product standards which in themselves support an essential safety requirement of a New Approach Directive and which make normative reference to this European Standard. This standard about “Non destructive testing Acoustic emission Equipment characteriz

18、ation” consists of the following parts: Part 1: Equipment description Part 2: Verification of operating characteristics Part one of this standard gives a description of the main components of an AE monitoring system. Part two of this standard gives methods and acceptance criteria for verifying the e

19、lectronic performance of an AE monitoring system. These methods and acceptance criteria are used to routinely check and verify the performance of an AE monitoring system composed of one or more channels during its life time. According to the CEN/CENELEC Internal Regulations, the national standards o

20、rganizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.Page 4 EN 13477-1:

21、2001 BSI 03-2001 1 Scope This European standard describes the main components that constitute an acoustic emission (AE) monitoring system comprising: detection; signal conditioning; signal measurement; analysis and output of results. 2 Normative references This European Standard incorporates by date

22、d or undated reference, provisions from other publications. These normatives references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard

23、only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies (including amendments). EN 1330-1, Non-destructive testing Terminology Part 1: List of general terms EN 1330-2, Non-destructive testing Terminology Part 2: Terms c

24、ommon to the non-destructive testing methods EN 1330-9, Non-destructive testing Terminology Part 9: Terms used in acoustic emission testing 3 Terms and definitions For the purpose of this standard the definitions given in EN 1330-1, EN 1330-2, EN 1330-9 and IEC 60050 International Electrotechnical V

25、ocabulary and the following apply: average signal level (ASL) rectified, time averaged AE signal. 4 Detection A piezoelectric sensor is the most commonly used device for detecting acoustic emission. It provides the most effective conversion of elastic waves (acoustic emission) into an electrical sig

26、nal in the frequency range most commonly used for AE detection, 20 kHz 1 MHz. In its simplest form it consists of a piezoelectric crystalline or ceramic element, mounted in a protective case. The sensor detects a combination of wave types: compressional, shear, surface (Rayleigh), plate (Lamb), arri

27、ving from any direction.Page 5 EN 13477-1:2001 BSI 03-2001 4.1 Sensing element The sensing material affects the conversion efficiency, operating temperature range and cable drive capability. Lead zirconate titanate (PZT), a ceramic, is the most commonly used material. It can be manufactured in a wid

28、e range of sizes and shapes. The size, shape and containment affect the sensitivity, directionality, frequency response and wave-mode response. Several elements may be combined to achieve a desired performance. 4.2 Sensor case The sensor case (usually metallic) determines the overall size and mechan

29、ical characteristics of the sensor. It may have an integral cable or a connector. The case provides a total electrical screening of the sensing element and is usually common to one pole of the sensing element. A faceplate of ceramic or epoxy between the sensor element and test object provides electr

30、ical isolation from the structure to avoid ground loop and induced electromagnetic noise. Depending on the method of assembly, the sensor can be made single ended or differential. In a single-ended device, the screen of a coaxial cable is connected to the sensor case and to one side of the sensing e

31、lement. In a differential device, a screened twisted pair cable is used and the sensing element is usually split or machined so that the screen does not conduct the electrical output signal. Differential sensors have normally improved immunity to electromagnetic noise compared with single-ended sens

32、ors. The case may contain a low noise preamplifier. Incorporating the preamplifier inside the sensor case, eliminates the cable link between the sensor element and the preamplifier. This reduces signal loss and improves immunity to electromagnetic noise. The drawbacks are that the sensor case become

33、s larger, the maximum temperature rating is limited by the electronics, and the preamplifier is not interchangeable, see also 5.1. 4.3 Sensor characteristics 4.3.1 Frequency response Piezoelectric acoustic emission sensors are either resonant with a peak in a certain frequency range, i.e. the freque

34、ncy content of the transient signal is mostly determined by the resonant frequency of the sensing element, or broad-band with a rather flat frequency response if properly damped. The response of a sensor is given in terms of its output voltage versus frequency for a standard mechanical stimulus. Due

35、 to the inertia of piezoelectric sensors their response will be different to continuous and transient stimuli. Most piezoelectric devices will be characterised by surface velocity (volts per metre per second) as a function of frequency for a transient input. An exception is the “flat response” devic

36、e that is often characterised in terms of surface displacement (volts per unit displacement). Continuous signal response may be characterised in the same way or in pressure terms (volts per microbar). 4.3.2 Directionality The directionality is a measure of the uniformity of the device response to si

37、gnals coming from any direction along the surface of the object to which the device is attached. It is usually called the polar response and quoted as a deviation about the mean in dB. Sensors may be intentionally directional to preferentially monitor a specific area. 4.3.3 Wave mode response Sensor

38、s may be made responsive to a particular wave mode, such as: shear, compressional or other waves.Page 6 EN 13477-1:2001 BSI 03-2001 4.3.4 Operating temperature This depends on the construction materials and the characteristics of the sensor element. It shall be used within the temperature range spec

39、ified by the manufacturers. 5 Signal conditioning Included in this section is preamplification, cables and post amplification. 5.1 Preamplifier The main preamplifier characteristics are the input impedance, noise, gain, bandwidth, filter characteristics such as roll-off rate, output impedance, opera

40、ting temperature range, common-mode rejection ratio (CMRR) and dynamic range. Preamplification can be of voltage or charge. Voltage preamplification converts the sensor output, usually a high impedance low-level signal, to a low impedance high-level signal for the transmission over long signal lines

41、 to the measurement instrumentation, which may be up to several hundred metres away. A typical preamplifier has a high input impedance, 40 dB gain and 50 output impedance to drive a coaxial cable. The D.C. power supply to the preamplifier is commonly supplied on the same cable as the signal output a

42、nd decoupled at each end using a filter network. The preamplifier input may be single-ended, differential or switchable to fit different sensor types. For some industrial applications, preamplifiers are an integral part of the AE sensor, providing greater ruggedness, reliability, reduced signal loss

43、 due to cable impedance and reduced susceptibility to electromagnetic noise. The design of the preamplifier may allow the sensor to be used as a pulser transducer for calibration purposes. Charge preamplification eliminates the effect of cable capacitance on the signal but is not widely used. 5.2 Ca

44、bles 5.2.1 Sensor to preamplifier cable This is the most important cable in the system and should be of low-capacitance, ( 100 pF/m), fully screened, and kept as short as possible ( 1 m) where voltage preamplification is used. 5.2.2 Preamplifier to instrument cable This is normally a screened coaxia

45、l 50 impedance cable matched to the preamplifier and measurement instrument. Care shall be taken to avoid crosstalk problems with multi-conductor cables, particularly if individual conductors are used to transmit a wide band pulser signal for periodic calibration during a test. 5.2.3 Screen A single

46、-point ground for all the screens is normally used at the measurement instrumentation. The screens of the cables shall not form ground loops.Page 7 EN 13477-1:2001 BSI 03-2001 5.3 Post-amplification and frequency filtering Post-amplification and further analogue filtering is used at the measurement

47、instrumentation to increase the signal level and remove unwanted low or high frequency signals for measurement purposes. The input impedance, dynamic range, filter characteristics, gain or attenuation are relevant to this section. The input stage usually provides D.C. power for the preamplifier and,

48、 sometimes, may control pulser operation. 6 Signal measurement 6.1 Continuous signal A continuous signal is characterised by the measurement of RMS (Root Mean Square) or ASL (Average Signal Level) with a particular time constant. Continuous signal measurement systems are used where there is no requi

49、rement to identify and characterise individual emissions (bursts), e.g., process monitoring and leak detection. The measured characteristics and their dynamic range define this type of system. 6.2 Burst signal Burst signal measurement systems identify and characterise individual acoustic emissions on the basis of their time above an amplitude threshold. The parameters of each burst signal may comprise any or all of the following, depending on the type of system and its user set-up: peak amplitude;