Review of Structural Health Monitoring Methods Regarding a Multi-Sensor Approach for Damage Assessment of Metal and Composite Structures

Abstract

Structural health monitoring (SHM) is the continuous on-board monitoring of a structure’s condition during operation by integrated systems of sensors. SHM is believed to have the potential to increase the safety of the structure while reducing its deadweight and downtime. Numerous SHM methods exist that allow the observation and assessment of different damages of different kinds of structures. Recently data fusion on different levels has been getting attention for joint damage evaluation by different SHM methods to achieve increased assessment accuracy and reliability. However, little attention is given to the question of which SHM methods are promising to combine. The current article addresses this issue by demonstrating the theoretical capabilities of a number of prominent SHM methods by comparing their fundamental physical models to the actual effects of damage on metal and composite structures. Furthermore, an overview of the state-of-the-art damage assessment concepts for different levels of SHM is given. As a result, dynamic SHM methods using ultrasonic waves and vibrations appear to be very powerful but suffer from their sensitivity to environmental influences. Combining such dynamic methods with static strain-based or conductivity-based methods and with additional sensors for environmental entities might yield a robust multi-sensor SHM approach. For demonstration, a potent system of sensors is defined and a possible joint data evaluation scheme for a multi-sensor SHM approach is presented.

Fiber Bragg Sensors Embedded in Cast Aluminum Parts: Axial Strain and Temperature Response

“…Monitoring of functional parts is of great interest and could help to improve the lifetime of these parts or to avoid failures in advance [ 1 , 2 ]. In the field of aerospace, embedded fiber optic sensors have been used as a real-time monitoring system in an aircraft with single-point, multi-point, or distributed sensors [ 3 , 4 , 5 , 6 ].…”

Lamb Wave Scattering Analysis for Interface Damage Detection between a Surface-Mounted Block and Elastic Plate

“…In recent decades, guided-wave-based structural health monitoring (SHM) has been developed with techniques that allow identification and estimation of cracks, delaminations, debondings, etc. [ 5 , 6 , 7 , 8 ]. Since GWs are dispersive, multimodal, and attenuating, their use for the purposes of SHM needs insight into physical phenomena and post-processing of the acquired signals, which have complex waveforms.…”

Crack Identification in Necked Double Shear Lugs by Means of the Electro-Mechanical Impedance Method

“…This is possible due to integrated and lightweight sensors mounted directly and permanently on the monitored structure. Sensor readings are processed and analyzed according to the applied SHM method [ 3 ]. Examples of state-of-the-art monitoring methods are guided waves [ 4 , 5 , 6 , 7 ], conductive surface layers [ 8 , 9 , 10 ], direct measurements of the electrical impedance of a structure [ 11 ] and the electro-mechanical impedance (EMI) method [ 12 , 13 , 14 , 15 ].…”