Tags

Type your tag names separated by a space and hit enter

Optical calibration for both out-of-plane and in-plane displacement sensitivity of acoustic emission sensors.
Ultrasonics. 2009 Dec; 49(8):623-7.U

Abstract

The use of piezoelectric sensors for acoustic emission (AE) monitoring provides an extremely sensitive detection method of AE events. The sensors are used to detect the stress waves, resulting from an AE event, which arrive at the surface of a structure. The sensors provide high sensitivity, and are generally based on a high-Q design where the sensor is used to detect AE events around its resonance. Sensitivity calibration of these sensors is essential for accurate assessment of the AE measurement and particularly important for sensors mounted on safety critical structures. This paper proposes an optical method which enables both the out-of-plane and in-plane displacement sensitivity of an AE sensor to be established independently from each other. In the method, a laser homodyne interferometer is used to measure the out-of-plane and in-plane displacement of the surface of a large test block excited by a repeatable source transducer. The out-of-plane displacement is measured by aligning the laser beam perpendicular to the surface with time gating of the receive waveform used to isolate only the direct arrival of the longitudinal wave produced by the piston source transducer. For the in-plane displacement measurement, the laser beam is aligned parallel to the surface to intersect a small optically reflective step with the time waveform being gated to measure only the direct shear arrival produced using a normal incidence shear wave source transducer. In each case, the interferometer measurement is followed by coupling the sensor under test to the measurement surface, which is then exposed to the same acoustic field and the sensor output signal measured. This substitution method allows the sensor sensitivity to be obtained in terms of volts per unit displacement for both the out-of-plane and the in-plane surface displacement. The method provides a comprehensive description of an AE sensor response to different planes of displacement and offers the potential for a traceable sensor calibration to units of length.

Authors+Show Affiliations

National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK. pete.theobald@npl.co.uk

Pub Type(s)

Evaluation Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19409592

Citation

Theobald, P D.. "Optical Calibration for Both Out-of-plane and In-plane Displacement Sensitivity of Acoustic Emission Sensors." Ultrasonics, vol. 49, no. 8, 2009, pp. 623-7.
Theobald PD. Optical calibration for both out-of-plane and in-plane displacement sensitivity of acoustic emission sensors. Ultrasonics. 2009;49(8):623-7.
Theobald, P. D. (2009). Optical calibration for both out-of-plane and in-plane displacement sensitivity of acoustic emission sensors. Ultrasonics, 49(8), 623-7. https://doi.org/10.1016/j.ultras.2009.03.004
Theobald PD. Optical Calibration for Both Out-of-plane and In-plane Displacement Sensitivity of Acoustic Emission Sensors. Ultrasonics. 2009;49(8):623-7. PubMed PMID: 19409592.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Optical calibration for both out-of-plane and in-plane displacement sensitivity of acoustic emission sensors. A1 - Theobald,P D, Y1 - 2009/03/27/ PY - 2007/12/05/received PY - 2009/03/18/revised PY - 2009/03/19/accepted PY - 2009/5/5/entrez PY - 2009/5/5/pubmed PY - 2009/12/16/medline SP - 623 EP - 7 JF - Ultrasonics JO - Ultrasonics VL - 49 IS - 8 N2 - The use of piezoelectric sensors for acoustic emission (AE) monitoring provides an extremely sensitive detection method of AE events. The sensors are used to detect the stress waves, resulting from an AE event, which arrive at the surface of a structure. The sensors provide high sensitivity, and are generally based on a high-Q design where the sensor is used to detect AE events around its resonance. Sensitivity calibration of these sensors is essential for accurate assessment of the AE measurement and particularly important for sensors mounted on safety critical structures. This paper proposes an optical method which enables both the out-of-plane and in-plane displacement sensitivity of an AE sensor to be established independently from each other. In the method, a laser homodyne interferometer is used to measure the out-of-plane and in-plane displacement of the surface of a large test block excited by a repeatable source transducer. The out-of-plane displacement is measured by aligning the laser beam perpendicular to the surface with time gating of the receive waveform used to isolate only the direct arrival of the longitudinal wave produced by the piston source transducer. For the in-plane displacement measurement, the laser beam is aligned parallel to the surface to intersect a small optically reflective step with the time waveform being gated to measure only the direct shear arrival produced using a normal incidence shear wave source transducer. In each case, the interferometer measurement is followed by coupling the sensor under test to the measurement surface, which is then exposed to the same acoustic field and the sensor output signal measured. This substitution method allows the sensor sensitivity to be obtained in terms of volts per unit displacement for both the out-of-plane and the in-plane surface displacement. The method provides a comprehensive description of an AE sensor response to different planes of displacement and offers the potential for a traceable sensor calibration to units of length. SN - 1874-9968 UR - https://www.unboundmedicine.com/medline/citation/19409592/Optical_calibration_for_both_out_of_plane_and_in_plane_displacement_sensitivity_of_acoustic_emission_sensors_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0041-624X(09)00030-4 DB - PRIME DP - Unbound Medicine ER -