ISO 22096:2007
(Main)Condition monitoring and diagnostics of machines — Acoustic emission
Condition monitoring and diagnostics of machines — Acoustic emission
ISO 22096:2007 specifies the general principles required for the application of acoustic emission 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 structure-borne measurements only.
Surveillance et diagnostic d'état des machines — Émission acoustique
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 22096
First edition
2007-07-15
Condition monitoring and diagnostics of
machines — Acoustic emission
Surveillance et diagnostic d'état des machines — Émission acoustique
Reference number
ISO 22096:2007(E)
©
ISO 2007
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ISO 22096:2007(E)
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ISO 22096:2007(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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established has the right to be represented on that committee. International organizations, governmental and
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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 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, shock and condition
monitoring, Subcommittee SC 5, Condition monitoring and diagnostics of machines.
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ISO 22096:2007(E)
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 techniques 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 data 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, 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.
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INTERNATIONAL STANDARD ISO 22096:2007(E)
Condition monitoring and diagnostics of machines — Acoustic
emission
1 Scope
This 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 structure-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.
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 — 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-borne
(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 document 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 application in machine
monitoring.
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ISO 22096:2007(E)
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 emission
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 cannot 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 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 source
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
machine
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 principal 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
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ISO 22096:2007(E)
4 Principle of the acoustic emission technology
4.1 Acoustic emission (AE) phenomenon
Acoustic 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 elastic 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
displacement 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 from 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 emission
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 rotational 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
⎯ susceptibility to attenuation,
⎯ susceptibility to high operational background noise, and
⎯ the inability to relate the resultant defect AE characteristics to the exac
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