1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58emission ICS 17.140.20; 17.160Condition monitoring and diagnostics of machines Acoustic BRITISH STA
2、NDARDBS ISO 22096:2007BS ISO 22096:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2007 BSI 2007ISBN 978 0 580 56839 8Amendments issued since publicationAmd. No. Date Commentscontract. Users are responsible for its correct appl
3、ication.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard is the UK implementation of ISO 22096:2007.The UK participation in its preparation was entrusted by Technical Committee GME/21, Mechanical vibration, shock and condition mo
4、nitoring, to Subcommittee GME/21/7, Condition monitoring.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numberISO 22096:2007(E)INTERNATIONAL STANDARD ISO22096Fi
5、rst edition2007-07-15Condition monitoring and diagnostics of machines Acoustic emission Surveillance et diagnostic dtat des machines mission acoustique BS ISO 22096:2007ii iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
6、 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 committee. International organizations, gover
7、nmental 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. International Standards are drafted in accordance with the rules given in the ISO/IEC D
8、irectives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member
9、bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 22096 was prepared by Technical Committee ISO/TC 108, Mechanical vibration
10、, shock and condition monitoring, Subcommittee SC 5, Condition monitoring and diagnostics of machines. BS ISO 22096:2007iv Introduction Acoustic emission (AE) technology can be used as a stand-alone condition monitoring technique that may also be employed to complement other condition monitoring tec
11、hniques based on other technologies (e.g. vibration, infrared, etc.) used for machine condition analysis and diagnosis/prognosis. Due to the nature of AE, an understanding of the operating mechanics of the monitored machine is not essential, but such an understanding allows the maximum amount of dat
12、a to be extracted from the results of the AE phenomena. As a diagnostic tool for machine condition monitoring, AE can be employed as a permanently installed, semi-permanent or portable system, depending on the criticality of the machine. Typically, an AE system would contain transducers, amplifiers,
13、 filters and data acquisition systems. Depending on the particular application, a range of AE characteristics can be extracted from the captured AE to provide indicators for machine condition monitoring. BS ISO 22096:20071Condition monitoring and diagnostics of machines Acoustic emission 1 Scope Thi
14、s International Standard specifies the general principles required for the application of acoustic emission (AE) to condition monitoring and diagnostics of machinery operating under a range of conditions and environments. It is applicable to all machinery and associated components and covers structu
15、re-borne measurements only. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies
16、. ISO 2041, Vibration and shock Vocabulary ISO 12718, Non-destructive testing Eddy current testing Vocabulary ISO 13372, Condition monitoring and diagnostics of machines Vocabulary ISO 18436-6, Condition monitoring and diagnostics of machines Requirements for training and certification of personnel
17、Part 6: Acoustic emission 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 2041, ISO 12718, ISO 13372 and the following apply. 3.1 acoustic emission machine monitoring range of phenomena that results in the generation of structure-borne and fluid-born
18、e (liquid, gas) propagating waves due to the rapid release of energy from localized sources within and/or on the surface of a material NOTE 1 Such a release may be a result of a process such as crack propagation, friction, impact, and leakage. NOTE 2 The definition of acoustic emission in this docum
19、ent conveys its broad application in machine monitoring. 3.2 acoustic emission monitoring machine monitoring detection and collection of information and acoustic emission data that indicate the state of a machine NOTE The definition of acoustic emission monitoring in this document relates to the app
20、lication in machine monitoring. BS ISO 22096:20072 3.3 acoustic emission sensor/receiver device containing a transducing element that converts elastic wave motion into an electrical signal 3.4 acoustic emission signal electrical signal from an acoustic emission sensor resulting from acoustic emissio
21、n 3.5 acoustic emission characteristics set of specific characteristics describing acoustic emission associated with a machine or an acoustic emission source NOTE The signature can be of a burst type, i.e. emission events which can be separated in time; or a continuous type, i.e. emissions which can
22、not be separated in time. 3.6 acoustic emission waveguide device which allows the transfer of elastic waves from the machine to an acoustic emission sensor 3.7 background noise false signals produced by causes other than acoustic emission, or by acoustic emission sources that are not relevant to the
23、 machine component being monitored NOTE This can include signals of electrical, thermal and mechanical origins. 3.8 couplant coupling media between an AE sensor and the object from which measurement is to be acquired EXAMPLES Oil, grease, adhesive bond, water-soluble paste, wax. 3.9 Hsu-Nielsen sour
24、ce pencil lead break device to simulate an acoustic emission event using the fracture of a brittle graphite lead in a suitable fitting NOTE Changes in signal can be due to variations in the lead. Typically, lead 2H of diameter 0,5 mm (alternatively 0,3 mm) and length (3,0 0,5) mm is used. 3.10 machi
25、ne mechanical system designed expressly to perform a specific task, such as the forming of material or the transference and transformation of motion, force or energy NOTE This is also sometimes referred to as equipment. 3.11 machine system machine train (deprecated) mechanical system in which the pr
26、incipal subsystem is a specific machine (3.10) and whose other subsystems are components and auxiliaries whose individual functions are integrated to support the actions and work of the machine BS ISO 22096:200734 Principle of the acoustic emission technology 4.1 Acoustic emission (AE) phenomenon Ac
27、oustic emission is a physical phenomenon occurring within and/or on the surface of materials. The term “acoustic emission” is used to describe the spontaneous elastic energy released by a process in the form of transient elastic waves. Acoustic emissions generated within a material manifest as elast
28、ic waves on the surface of the material and cover a broad frequency range. Typically, the frequency content of detected acoustic emission signals falls within the range of 20 kHz to 1 MHz. The waves associated with AE are detected by the use of a suitable sensor that converts the surface displacemen
29、t of the material into an electrical signal. These electrical signals are processed by appropriate instrumentation and/or data processing techniques to characterize the system condition and to aid in detection of the early stages of loss of mechanical and structural integrity. The signal waveform fr
30、om the sensor is affected by multiple path propagation and several wave modes that are generated in and/or on the material. As such, the sensor response for identical input sources that propagate through varying transmissions paths will be different. 4.2 Advantages and limitations of acoustic emissi
31、on AE offers the following advantages: a) it is non-invasive; b) it provides real-time process information; c) due to its higher sensitivity, it may offer earlier fault detection than vibration analysis; d) it offers monitoring of dynamic performance; e) it may be applied to a wide range of rotation
32、al speeds with significant advantages at slow rotational speeds of the order of less than 1 Hz (60 r/min); f) it allows for detection of the friction/wear process, for instance, rubbing between loose mating components or deterioration in lubricating condition. Limitations of AE include susceptibilit
33、y to attenuation, susceptibility to high operational background noise, and the inability to relate the resultant defect AE characteristics to the exact fault mechanism. 5 Applications of the acoustic emission technique 5.1 Machinery monitored by acoustic emission Acoustic emission technology may be
34、applied to a wide range of machinery, provided a transmission path from the position of the sensor to the region of interest exists. This is particularly important for structure-borne AE monitoring; some examples are detailed in Table 1. The method does not rely on absolute quantities of measured AE
35、 parameters but on trends of AE parameters that are measured during a specified operational condition. For instance, an increasing trend in the detected AE signal level under steady operating conditions is indicative of machine deterioration; AE signal amplitude modulated at a bearing defect frequen
36、cy is indicative of early stages of bearing element defect, which may not be detectable with vibration or shock pulse BS ISO 22096:20074 monitoring. It should be noted that AE activity will vary for differing machines, operating conditions and machine loading. Table 1 Examples of applications of AE
37、to machine condition monitoring Fault Machine type Bearing deterior-ation Mechanical seal rubbing Wear Lubricant contamin-ation and loss of lubricant Severe mis-alignment Mounting faults Process monitoring, including leakage, performance, etc. Pump Gear box Electric motor Steam turbine Industrial ga
38、s turbine Electric generator Diesel engine Machining processes Fan or blower Slow-speed rotating machine (typically 60 r/min) Machine components, e.g. valves, heat exchangers Compressors (air, gas, etc.) 5.2 Interference factors Prior to performing an AE measurement, it is very important to be aware
39、 of potential noise sources, such as electronic noise (electromagnetic and radio frequency interference), airborne noise (such as gas leaks or the impact of sand particles on the machine in windy environments), operational background noise (flow of fluids in pipes) and mechanical background noise, w
40、hose presence might affect the AE measurement. BS ISO 22096:200756 Data acquisition 6.1 Installing a system A schematic diagram of a typical structure-borne AE data acquisition system is illustrated in Figure 1. Typically the sensor is coupled to the machine under observation. This in turn is usuall
41、y connected to a pre-amplifier, which is connected to an acquisition system. Some AE sensors have built-in pre-amplifiers. The data shall be acquired while the machine is operational and the amount of data acquired and extent of analysis depends upon the particular application. The system can be per
42、manent, semi-permanent or portable. Figure 1 Schematic diagram of an acquisition system 6.2 AE instrumentation and sensors Detection is the most important part of an AE chain and every attempt should be undertaken to overcome poor installation and acoustical coupling. Furthermore, the effects of inc
43、orrect frequency selection for filters, sensors, acquisition rates, etc, should be considered. Instruments and sensors may be characterized and calibrated to EN 13477-1, EN 13477-2, ASTM E 1106-86 and ASTM E976-05. In addition, sensor parameters that shall be considered include size, sensitivity, fr
44、equency response and environment. In circumstances where appropriate, for instance large circular bearings, an array of transducers may be necessary for source location. Location could be achieved by a number of methods; AE wave arrival time is one such method. 6.3 Sensor installation and coupling m
45、edia for structure-borne monitoring For structure-borne monitoring, the purpose of the mounting arrangement is to ensure the sensor is fixed onto a structure with an adequate coupling media (couplant). Mounting methods will be either a mechanical arrangement (compression force applied with a magnet,
46、 mechanical clamp, etc.) or the use of an adhesive. In the latter instance, the adhesive also serves as the couplant. The location of the AE sensor should ensure a transmission path to the machine component under observation. This path can include surface discontinuities (a discontinuity is defined
47、as an interface, for instance, the interface between a bolt head and the clamped component). However, these surfaces should be in contact either directly or across a couplant (e.g. a transmission path across a plain journal bearing where the lubricating and cooling oil serves as the couplant for tra
48、nsmission). In addition, the surface onto which the sensor is placed shall be clean. The signal transmission path can be improved by removing any surface paint to expose the metal substrate; however removal of any coat should not degrade the machine integrity or performance. Every attempt shall be m
49、ade to ensure that the face of the sensor is fixed flat onto the surface, avoiding surface curvature, contaminating particles or surface discontinuities. The primary purpose of this procedure is to improve transmission paths and to ensure repeatability. Under certain conditions, the AE sensor may be installed on a waveguide. Usually the waveguide is constructed to ensure a more direct transmiss
