Acoustic Techniques for Structural Health Monitoring

Abstract

Future safety and maintenance strategies for industrial components and vehicles are based on combinations of monitoring systems, which are permanently attached to or embedded in the structure, and periodic inspections. The latter belong to conventional nondestructive evaluation (NDE) and can be enhanced or partly replaced by structural health monitoring systems. However, the main benefit of this technology in the far future will consist in systems can be designed differently based on an improved safety philosophy that includes continuous monitoring. This approach will increase the efficiency of inspection procedures and reduce inspection time. The Dresden branch of Fraunhofer IZFP has developed network nodes, miniaturized transmitters and receiver systems for active and passive acoustic techniques and sensor systems that can be attached to or embedded in components or structures. These systems have been used to demonstrate intelligent sensor networks for monitoring of aerospace structures, railway systems, wind energy generators, pipes and others. Defects have been detected and monitored during full scale fatigue tests. This paper will discuss opportunities and future trends in nondestructive evaluation and health monitoring based on new sensor principles and advanced microelectronics. It will outline various application examples of monitoring systems based on acoustic techniques and will denote further needs for research and development.

Experimental Study of Acoustic Noise Correlation Technique for Passive Monitoring of Rails

“…Automated vision systems have been developed to eliminate or minimize the visual inspections by humans, but still detection is limited to visible anomalies. Existing technologies for finer local inspection and detection of early damage include: eddy current [3], fiber optic sensors [4] [5], and naturally ultrasound NDT using either contact or contact-less acoustic sensors [6] [7] [8] [9] [10]. Though efficient, these methods ordinarily require planning interventions depending on traffic.…”

ZigBee Sensor Network Platform for Health Monitoring of Rails Using Ambient Noise Correlation

“…Other technologies for finer local inspection and detection of early damage were developed including: eddy current [3] and fiber optic sensors [4,5]. Emission-reception of ultrasound waves is also well-known method in the railway industry [6][7][8][9][10]. Though efficient, these methods ordinarily require planning interventions depending on traffic.…”