Limits...
MEMS Microphone Array Sensor for Air-Coupled Impact-Echo.

Groschup R, Grosse CU - Sensors (Basel) (2015)

Bottom Line: By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved.The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation.The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

View Article: PubMed Central - PubMed

Affiliation: Technische Universität München (TUM), Chair of Non-destructive Testing, Baumbachstr. 7, 81245 Munich, Germany. robin.groschup@tum.de.

ABSTRACT
Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved. The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation. The proposed sensing strategy is justified with findings from numerical simulations, showing that the IE resonance in plate like structures causes coherent surface displacements on the specimen under test in an area around the impact location. Therefore, by placing several MEMS microphones on a sensor array board, the IE resonance is easier to be identified in the recorded spectra than with single point microphones or contact type transducers. A comparative measurement between the array sensor, a conventional accelerometer and a measurement microphone clearly shows the suitability of MEMS type microphones and the advantages of using these microphones in an array arrangement for IE. The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

No MeSH data available.


Sound sources acting on sensors in air-coupled Impact-Echo (IE).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4541815&req=5

sensors-15-14932-f005: Sound sources acting on sensors in air-coupled Impact-Echo (IE).

Mentions: For optimizing the sensitivity of an air-coupled sensor for IE purposes, two approaches can be considered. Either the plane wave fronts emerging from the air-coupled ZGV-S1 mode could be physically focused towards a single microphone [21] or the air-coupled waves could be sensed by an array arrangement of microphones within the zone where the ZGV-S1 mode produces in-phase pressure changes. We focus on the latter approach since it brings a number of operational advantages. Based on the findings from the simulation, IE measurements can be effectively performed by placing several receivers in a region around the impact location that stretches approximately up to the plate thickness (the first nodal point of the ZGV-S1 Lamb mode). All of these sensors would receive the same waveform information and therefore the summed output of these receivers would be more sensitive to the displacements of the plate surface due to the thickness resonance than the output of a single receiver alone. This fact comes in quite handy when using air-coupled sensing with microphones since such sensors will always pick up unwanted energy from ambient noise or noise from the direct impact (Figure 5).


MEMS Microphone Array Sensor for Air-Coupled Impact-Echo.

Groschup R, Grosse CU - Sensors (Basel) (2015)

Sound sources acting on sensors in air-coupled Impact-Echo (IE).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541815&req=5

sensors-15-14932-f005: Sound sources acting on sensors in air-coupled Impact-Echo (IE).
Mentions: For optimizing the sensitivity of an air-coupled sensor for IE purposes, two approaches can be considered. Either the plane wave fronts emerging from the air-coupled ZGV-S1 mode could be physically focused towards a single microphone [21] or the air-coupled waves could be sensed by an array arrangement of microphones within the zone where the ZGV-S1 mode produces in-phase pressure changes. We focus on the latter approach since it brings a number of operational advantages. Based on the findings from the simulation, IE measurements can be effectively performed by placing several receivers in a region around the impact location that stretches approximately up to the plate thickness (the first nodal point of the ZGV-S1 Lamb mode). All of these sensors would receive the same waveform information and therefore the summed output of these receivers would be more sensitive to the displacements of the plate surface due to the thickness resonance than the output of a single receiver alone. This fact comes in quite handy when using air-coupled sensing with microphones since such sensors will always pick up unwanted energy from ambient noise or noise from the direct impact (Figure 5).

Bottom Line: By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved.The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation.The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

View Article: PubMed Central - PubMed

Affiliation: Technische Universität München (TUM), Chair of Non-destructive Testing, Baumbachstr. 7, 81245 Munich, Germany. robin.groschup@tum.de.

ABSTRACT
Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved. The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation. The proposed sensing strategy is justified with findings from numerical simulations, showing that the IE resonance in plate like structures causes coherent surface displacements on the specimen under test in an area around the impact location. Therefore, by placing several MEMS microphones on a sensor array board, the IE resonance is easier to be identified in the recorded spectra than with single point microphones or contact type transducers. A comparative measurement between the array sensor, a conventional accelerometer and a measurement microphone clearly shows the suitability of MEMS type microphones and the advantages of using these microphones in an array arrangement for IE. The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

No MeSH data available.