Development of a low‐power wireless acoustic emission sensor node for aerospace applications

Stephen Grigg,Carol Ann Featherston,Andrew Parkins,Robert Cooper,Rhys Pullin,Matthew Pearson,David Jenman

doi:10.1002/stc.2701

Stephen Grigg, Carol Ann Featherston + Show 5 more

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https://doi.org/10.1002/stc.2701

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Abstract

Acoustic emission (AE) is the spontaneous release of energy caused by the growth of damage, the monitoring of which gives an indication of the presence of damage within a structure. The current standard for AE localisation is difficult to apply in a low‐power system as sensors must either be wired together or Node's time synchronised, which is power intensive. This paper proposes the use of a method of bonding three piezoelectric sensors in a small triangular array, which has previously been shown by Aljets et al. to be capable of locating sources in simple structures. In this prior work the wave's A0 mode was used to predict the angle of arrival and the distance the wave has travelled through single sensor modal analysis. This paper presents the development of hardware to apply this technique and testing that showed artificial sources could be located in simple plates to a good level of accuracy. The addition of complexity to structures significantly reduced accuracy. This prompted hardware modifications to use the S0 mode for angle prediction. Testing showed that this significantly improved performance in a complex composite structure. The power consumption of the device is very low, consuming 0.33 mW in sleep mode, 17.44 mW whilst waiting for an event and 38 mW to record, process and transmit an event. This level of consumption has the potential to be self‐powered via energy harvesting.

Highlights

Structural health monitoring (SHM) is the process of collecting data from a structure throughout its entire life, with the aim of identifying and tracking the growth of damage
Including strain, vibration and temperature monitoring.[2]. These methods can be useful to assist with understanding the stresses put on the aircraft during its life, enabling predictions of damage locations.[1]
The addition of complexity to both panels significantly reduced the accuracy and range of the system. This was due to S0 to A0 mode conversion making the A0 mode's arrival time difficult to predict; this was made more difficult by the A0 mode's increased attenuation rate compared to the S0 mode's when crossing stiffeners.[32]

Summary

Introduction

Structural health monitoring (SHM) is the process of collecting data from a structure throughout its entire life, with the aim of identifying and tracking the growth of damage. This benefits safety but can enable aircraft life extension and reduced maintenance downtime, both of which increase profitability.[1] it has the potential to allow for optimally designed structures if confidence in the identification of damage can be ensured, reducing weight and fuel consumption. A range of SHM techniques have been employed on aircraft. Including strain, vibration and temperature monitoring.[2] These methods can be useful to assist with understanding the stresses put on the aircraft during its life, enabling predictions of damage locations.[1] They do not inform of the presence of damage, something that ultrasonic techniques do

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