Structural Health and Condition Monitoring with Acoustic Emission and Guided Ultrasonic Waves: What about Long-Term Durability of Sensors, Sensor Coupling and Measurement Chain?

Andreas J Brunner

doi:10.3390/app112411648

Andreas J Brunner

Open Access

https://doi.org/10.3390/app112411648

Copy DOI

Abstract

Acoustic Emission (AE) and Guided Ultrasonic Waves (GUWs) are non-destructive testing (NDT) methods in several industrial sectors for, e.g., proof testing and periodic inspection of pressure vessels, storage tanks, pipes or pipelines and leak or corrosion detection. In materials research, AE and GUW are useful for characterizing damage accumulation and microscopic damage mechanisms. AE and GUW also show potential for long-term Structural Health and Condition Monitoring (SHM and CM). With increasing computational power, even online monitoring of industrial manufacturing processes has become feasible. Combined with Artificial Intelligence (AI) for analysis this may soon allow for efficient, automated online process control. AI also plays a role in predictive maintenance and cost optimization. Long-term SHM, CM and process control require sensor integration together with data acquisition equipment and possibly data analysis. This raises the question of the long-term durability of all components of the measurement system. So far, only scant quantitative data are available. This paper presents and discusses selected aspects of the long-term durability of sensor behavior, sensor coupling and measurement hardware and software. The aim is to identify research and development needs for reliable, cost-effective, long-term SHM and CM with AE and GUW under combined mechanical and environmental service loads.

Highlights

The physical phenomena of Acoustic Emission (AE) and Ultrasonics (UT), the latter providing the basis for the Non-Destructive Test (NDT) method of Guided Ultrasonic
AE and Guided Ultrasonic Waves (GUWs) [6] are complementary methods in the following sense: AE is passively monitoring and recording elastic waves that propagate to the surface of the test objects, whereas GUWs, the same as UT, are elastic waves actively excited at a given location and time and recorded after propagation in the test object by another UT transducer
The information presented from the literature suggests the following aspects that deserve attention when planning and implementing AE or GUW for long term SHM or Condition Monitoring (CM): (1) performance of the couplant material and of the mounting device; (2) assuring sufficiently constant sensor sensitivity; (3) hardware and software development; (4) signal transmission and data storage; and (5) maintenance and repair concepts

Summary

Introduction

Waves (GUW), have been observed and investigated since the early 1930s (see [1,2,3]). It took until the late 1960s for the implementation of AE and GUW as technically applicable NDT methods. These developments and selected industrial applications are described in, e.g., the NDT Handbooks on AE [4] and on UT [5] published by the American. AE systems currently have a function for sending a “short” voltage pulse (duration of μs or less) to the AE sensors in some systems adaptable or provided by a suitably amplified function generator signal.

Methods

Findings

Discussion

Conclusion