A Development Strategy for Structural Health Monitoring Applications

Abstract

Permanently installed SHM systems are now a viable alternative to traditional periodic inspection (NDT). However, their industrial use is limited and this paper reviews the steps required in developing practical SHM systems. The transducers used in SHM are fixed in location, whereas in NDT they are generally scanned. The aim is to reach similar performance with high temporal frequency, low spatial frequency SHM data to that achievable with conventional high spatial frequency, low temporal frequency NDT inspections. It is shown that this can be done via change tracking algorithms such as the Generalized Likelihood Ratio (GLR) but this depends on the input data being normally distributed, which can only be achieved if signal changes due to variations in the operating conditions are satisfactorily compensated; there has been much recent progress on this topic and this is reviewed. Since SHM systems can generate large volumes of data, it is essential to convert the data to actionable information, and this step must be addressed in SHM system design. It is also essential to validate the performance of installed SHM systems, and a methodology analogous to the model assisted POD (MAPOD) scheme used in NDT has been proposed. This uses measurements obtained from the SHM system installed on a typical undamaged structure to capture signal changes due to environmental and other effects, and to superpose the signal due to damage growth obtained from finite element predictions. There is a substantial research agenda to support the wider adoption of SHM and this is discussed.

Case Studies about Finite Element Modeling and Wireless Sensing of Three Pennsylvania Bridges

“…One of the complementary approaches is offered by structural health monitoring (SHM) in which sensors of different kinds are bonded/bolted/embedded to the structure of interest and stream real-time measurements to a central repository where smart processing is performed with the goal of flagging critical issues as they unfold. As noted by Cawley [ 4 ], the replacement of periodic inspection of engineering structures with SHM systems has been discussed for many years. However, the industrial take-up of SHM technology has been slow due to organizational and business case issues as well as significant technical challenges [ 4 ].…”

“…As noted by Cawley [ 4 ], the replacement of periodic inspection of engineering structures with SHM systems has been discussed for many years. However, the industrial take-up of SHM technology has been slow due to organizational and business case issues as well as significant technical challenges [ 4 ]. Nonetheless, SHM, which sits at the crossroads of sensor technology, signal processing, and structural engineering, has seen rapid growth in various research [ 5 , 6 , 7 , 8 ].…”

Probability of detection, localization, and sizing: The evolution of reliability metrics in Structural Health Monitoring

“…The need of performance validation was also outlined in a recent publication of the same author. 15 The MIL-HKBK-1823A 16 allows the assessment of NDE methods exploiting the concept of Probability of Detection (POD) curves. However, there is a lack of specific guidelines and procedures to evaluate the system monitoring capabilities in the field of SHM.…”