Crack monitoring using multiple smart materials; fiber-optic sensors & piezo sensors

Muneesh Maheshwari,Venu G M Annamdas,John H L Pang,Anand Asundi,Swee C Tjin

doi:10.1080/19475411.2017.1298220

Abstract

ABSTRACTThis article focuses on health monitoring of structures using multiple smart materials. In this research, two fiber-optic sensors, namely fiber Bragg grating (FBG) and fiber-optic polarimetric sensor (FOPS), are investigated for damage detection in the beam specimen. FBG is used for local strain measurement while FOPS is used for global strain measurement. Both FBG and FOPS show significant changes in the strain due to damages in the specimen. Also, at the center of the specimen, piezoelectric wafer active sensor (PWAS) is attached. The electromechanical admittance (EMA) signature of the specimen beam is recorded by PWAS. The changes in the amplitudes of the peaks obtained at various frequencies in this EMA signature are analyzed, and it is shown that the peak amplitudes respond differently to damages and to change in loading. Thus, multiple smart materials (FBG, FOPS, and PWAS) are used to get improved information on the health of the beam.

Highlights

Large and heavy mechanical and civil structures need to be monitored on a regular basis for cracks or damages
The changes in the amplitudes of the peaks obtained at various frequencies in this electromechanical admittance (EMA) signature are analyzed, and it is shown that the peak amplitudes respond differently to damages and to change in loading
This article presents the application of multiple smart materials, fiber Bragg grating (FBG), fiber-optic polarimetric sensor (FOPS), and piezoelectric wafer active sensor (PWAS), for crack monitoring in a fixed-fixed beam

Summary

Introduction

Large and heavy mechanical and civil structures need to be monitored on a regular basis for cracks or damages. The strain changes abruptly in these structures due to damages. Different smart materials are being used to monitor the health of structures. Fiber-optic sensors and piezoelectric wafer active sensor (PWAS) are among the most used smart materials for structural health monitoring (SHM). The increased strain due to the damage or crack in a structure is picked up by FOPS irrespective of the damage location in the structure. FOPS monitors damages in different structures globally [14,15,16]. This article presents the application of multiple smart materials, FBG, FOPS, and PWAS, for crack monitoring in a fixed-fixed beam. FOPS is used for global strain measurement in this research for the first time. The impact of the cracks on EMA signature is abrupt and higher, while on the other hand, loading makes a steadier and lower impact on the EMA signature

Theory

Experiments and results

Monitoring with FOPS

Monitoring with PWAS

Conclusions

Notes on contributors