Structural health monitoring

About: Structural health monitoring is a research topic. Over the lifetime, 11727 publications have been published within this topic receiving 186231 citations.

Assessment of an extrinsic polymer-based optical fibre sensor for structural health monitoring

Abstract: Plastic optical fibre sensors offer remarkable ease of handling, and recent research has shown their potential as a low-cost sensor for damage detection and structural health monitoring applications. This paper presents details of a novel extrinsic polymer-based optical fibre sensor and the results of a series of mechanical tests conducted to assess its potential for structural health monitoring. The intensity-based optical fibre sensor proposed in this study relies on the modulation of light intensity as a function of a physical parameter (typically strain) as a means to monitor the response of the host structure to an applied load. Initially, the paper will reveal the design of the sensor and provide an outline of the sensor fabrication procedure followed by a brief description of its basic measurement principle. Two types of sensor design (fluid type and air type) will be evaluated in terms of their strain sensitivity, linearity and signal repeatability. Results from a series of quasi-static tensile tests conducted on an aluminium specimen with four surface-attached optical fibre sensors showed that these sensors offer excellent linear strain response over the range of the applied load. A comparison of the strain response of these sensors highlights the significant improvement in strain sensitivity of the liquid-filled-type sensor over the air-filled-type sensor. The specimens were also loaded repeatedly over a number of cycles and the findings exhibited a high degree of repeatability in all the sensors. Free vibration tests based on a cantilever beam configuration (where the optical fibre sensor was surface bonded) were also conducted to assess the dynamic response of the sensor. The results demonstrate excellent agreement with electrical strain gauge readings. An impulse-type loading test was also performed to assess the ability of the POF sensor to detect the various modes of vibration. The results of the sensor were compared and validated by a collocated piezofilm sensor highlighting the potential of the POF sensor in detecting the various eigen-frequencies of the vibration. Finally, preliminary results of a loading–unloading test of the same sensor design encased within a metal tube will be presented. The results obtained were encouraging offering the possibilities of employing the proposed device as an embedded sensor for damage detection in concrete beams.

Ultrasonic wave-based structural health monitoring embedded instrument

Abstract: Piezoelectric sensors and actuators are the bridge between electronic and mechanical systems in structures. This type of sensor is a key element in the integrity monitoring of aeronautic structures, bridges, pressure vessels, wind turbine blades, and gas pipelines. In this paper, an all-in-one system for Structural Health Monitoring (SHM) based on ultrasonic waves is presented, called Phased Array Monitoring for Enhanced Life Assessment. This integrated instrument is able to generate excitation signals that are sent through piezoelectric actuators, acquire the received signals in the piezoelectric sensors, and carry out signal processing to check the health of structures. To accomplish this task, the instrument uses a piezoelectric phased-array transducer that performs the actuation and sensing of the signals. The flexibility and strength of the instrument allow the user to develop and implement a substantial part of the SHM technique using Lamb waves. The entire system is controlled using configuration software and has been validated through functional, electrical loading, mechanical loading, and thermal loading resistance tests.

Experimental and numerical studies on model updating method of damage severity identification utilizing four cost functions

Abstract: SUMMARY As the final stage of damage identification, damage severity identification has great significance to structural safety assessment and decision-making in maintenance. Take the damage detection of truss structures for instance; the stochastic damage locating vector method has great advantages. However, the method is a localization technique designed to provide information in damage location only. Many present damage severity identification methods suffer from great error due to high noise. Therefore, it is imperative to develop a new identification method for truss structural health monitoring. To solve this problem, this paper presents the model updating method of damage severity identification based on four cost functions: (i) correlation coefficient of free vibration accelerations; (ii) correlation coefficient of local mode shapes; (iii) free vibration accelerations assurance criterion; and (iv) local modal assurance criterion. In these functions, correlation coefficient and correlation degree of free vibration accelerations of measured nodes are first proposed to identify damage severity. Moreover, a simple supported bailey steel-truss bridge Benchmark Model has been designed and constructed. The span is 8 m with the scaled ratio 1:25. Based on the model, both experimental and numerical simulation results using these procedures under pulse excitation indicate that they are feasible and effective. In addition, the proposed techniques exhibit high-noise insusceptibility. Copyright © 2011 John Wiley & Sons, Ltd.

Ant lion optimisation algorithm for structural damage detection using vibration data

Abstract: Structural damage assessment is crucial for structural health monitoring to evaluate the safety and residual service life of the structure. To solve the structural damage detection problem, various optimisation techniques have been in use. However, they fail to identify damage and are prone to converge to local optima for improper tuning of algorithm-specific parameters, which are problem specific. In this study, the recently proposed ant lion optimiser, which is a population-based search algorithm, mimicked the hunting behaviour of antlions, was used for assessing structural damage. The objective function for damage detection was based on vibration data, such as natural frequencies and mode shapes. The effectiveness of the proposed technique was evaluated against several benchmark problems with different damage settings. The results indicate that the proposed algorithm required fewer parameters than other metaheuristic algorithms to identify the location and extent of damage.