Standards Development

Scope

This International Standard describes the method of determining the receiving sensitivity spectrum of a piezoelectric acoustic emission sensor under test, stimulated by a particle motion pulse in normal direction to the sensor’s face from a directly coupled piezoelectric transducer. The particle motion pulse of each transducer to be used is once measured at the free surface of the transducer by a scanning laser vibrometer in absolute units of particle velocity. The determined receiving sensitivity is scaled to the free motion (in absence of the sensor) considering the acoustic impedance of the material where the sensor is mounted to and assuming a longitudinal wave arrival at the sensor in normal direction. Transducers are selected for an optimum uniformity of motion distribution over their active face. This document does not include the effects on a sensor’s response spectrum caused by a non-uniform motion distribution, due to e.g. a longitudinal wave arrival from another than normal direction, or when Rayleigh or plane waves are passing by the sensitive face.

Purpose

The receiving sensitivity spectrum is the most important characteristics of an AE sensor. A noncontroversial, feasible, internationally standardized method of sensitivity determination is needed to establish uniformity of acoustic emission testing, data correlation, interpretation and meaningful exchange of data between different research teams at different times. Certain standards for AE testing of e.g. safety critical structures define requirements on the sensitivity spectrum what needs a feasible and standardized method for its determination.

The following summarizes the problems with current standards dealing with that topic:

ISO 12713:1998 (primary calibration), almost a copy of ASTM E1106, but E1106 has been revised in 2012, but not ISO 12713. NIST (USA), the only neutral offerer of calibration service owning a prototype according to E1106:2012 stopped offering AE calibration service.

ISO 12714:1999 (secondary calibration), almost a copy of ASTM E1781, but E1781 has been revised in 2013, but not ISO 12714. ISO12714/ASTM E1781 require a standard sensor calibrated according to E1106. Since NIST (USA) stopped offering external calibration service, no such sensor can be made available to organizations interested in an installation of a new calibration setup. Therefore, work for a revision of ISO 12714 has been cancelled in 2018.

ISO TR13115 (a not normative Technical Report on reciprocal calibration method) is highly controversial: Prof. Kanji Ono, an AE expert enjoying an outstanding reputation, concludes in his publication (http://dx.doi.org/10.1080/09349847.2017.1375585): on page 44„…This implies that standards, such as NDIS2109/ISO-TR13115, have no foundation as it is based on the flawed theory and procedures.”

The new proposal shall solve the problem described above. In addition it is helpful for each user of an AE-system since it lets one quickly verify the sensitivity of any item in an inventory of AE sensors. The new method is an improved version of the method most AE sensor manufacturers are using for many years. That method has been criticized by Burks & Hamstad in a 2014 published paper (--link--). The items criticized will be solved by the proposed method

The instrumentation needed to perform the method is rather cheap compared to that for the abovementioned standards, therefore, the method will be affordable for many AE service providers and many research laboratories dealing with AE projects.

The receiving sensitivity spectrum is the most important characteristics of an AE sensor. A noncontroversial, feasible, internationally standardized method of sensitivity determination is needed to establish uniformity of acoustic emission testing, data correlation, interpretation and meaningful exchange of data between different research teams at different times. Certain standards for AE testing of e.g. safety critical structures define requirements on the sensitivity spectrum what needs a feasible and standardized method for its determination.

The following summarizes the problems with current standards dealing with that topic:

ISO 12713:1998 (primary calibration), almost a copy of ASTM E1106, but E1106 has been revised in 2012, but not ISO 12713. NIST (USA), the only neutral offerer of calibration service owning a prototype according to E1106:2012 stopped offering AE calibration service.

ISO 12714:1999 (secondary calibration), almost a copy of ASTM E1781, but E1781 has been revised in 2013, but not ISO 12714. ISO12714/ASTM E1781 require a standard sensor calibrated according to E1106. Since NIST (USA) stopped offering external calibration service, no such sensor can be made available to organizations interested in an installation of a new calibration setup. Therefore, work for a revision of ISO 12714 has been cancelled in 2018.

ISO TR13115 (a not normative Technical Report on reciprocal calibration method) is highly controversial: Prof. Kanji Ono, an AE expert enjoying an outstanding reputation, concludes in his publication (http://dx.doi.org/10.1080/09349847.2017.1375585): on page 44„…This implies that standards, such as NDIS2109/ISO-TR13115, have no foundation as it is based on the flawed theory and procedures.”

The new proposal shall solve the problem described above. In addition it is helpful for each user of an AE-system since it lets one quickly verify the sensitivity of any item in an inventory of AE sensors. The new method is an improved version of the method most AE sensor manufacturers are using for many years. That method has been criticized by Burks & Hamstad in a 2014 published paper (--link--). The items criticized will be solved by the proposed method

The instrumentation needed to perform the method is rather cheap compared to that for the abovementioned standards, therefore, the method will be affordable for many AE service providers and many research laboratories dealing with AE projects.