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.

Damage detection under ambient vibration by harmony search algorithm

Abstract: Highlights? A new approach for vibration-based (SHM) procedures is presented. ? Stochastic system identification with the evolutionary harmony search algorithm. ? Numerical investigation considering noise levels and a series of damage scenarios. ? Experimental study of three cantilever beams under different damage conditions. ? The methodology has shown potential for use in the damage assessment of structures. Damage in structural systems induced by vibrations, alternating load cycles, temperature changes, corrosion, etc., constitute a serious technical problem. Smart methods of control and structural health monitoring (SHM) for large structures are, therefore, highly needed. In certain structural applications, moreover, a lack of access to the damaged area imposes an additional constraint on damage identification procedures. One method that may fulfill those requirements is dynamic nondestructive testing, which consists of monitoring changes in the structure's natural frequencies, vibration modes and damping.In this paper, a new approach for vibration-based (SHM) procedures is presented, in an ambient vibration context; this method combines a time domain modal identification technique (SSI) with the evolutionary harmony search algorithm. A series of numerical examples with different damage scenarios and noise levels have been carried out under impact and ambient vibration. Thereafter, an experimental study of three cantilever beams with several different damage scenarios is conducted and the proposed methodology has shown potential for use in the damage diagnosis assessment of the remaining structural life.

PVDF Multielement Lamb Wave Sensor for Structural Health Monitoring

Abstract: The characteristics of Lamb waves, which are multimodal and dispersive, provide both challenges and opportunities for structural health monitoring (SHM). Methods for nondestructive testing with Lamb waves are well established. For example, mode content can be determined by moving a sensor to different positions and then transforming the spatial-temporal data into the wavenumber-frequency domain. This mode content information is very useful because at every frequency each mode has a unique wavestructure, which is largely responsible for its sensitivity to material damage. Furthermore, mode conversion occurs when the waves interact with damage, making mode content an excellent damage detection feature. However, in SHM, the transducers are typically at fixed locations and are immovable. Here, an affixed polyvinylidene fluoride (PVDF) multielement sensor is shown to provide these same capabilities. The PVDF sensor is bonded directly to the waveguide surface, conforms to curved surfaces, has low mass, low profile, low cost, and minimal influence on passing Lamb waves. While the mode receivability is dictated by the sensor being located on the surface of the waveguide, both symmetric and antisymmetric modes can be detected and group velocities measured.

Frequency selective surface based passive wireless sensor for structural health monitoring

Abstract: Wireless sensor networks or ubiquitous sensor networks are a promising technology giving useful information to people. In particular, the chipless passive wireless sensor is one of the most important developments in wireless sensor technology because it is compact and does not need a battery or chip for the sensor operation. So it has many possibilities for use in various types of sensor system with economical efficiency and robustness in harsh environmental conditions. This sensor uses an electromagnetic resonance frequency or phase angle shift associated with a geometrical change of the sensor tag or an impedance change of the sensor. In this paper, a chipless passive wireless structural health monitoring (SHM) sensor is made using a frequency selective surface (FSS). The cross type FSS is introduced, and its SHM principle is explained. The electromagnetic characteristics of the FSS are simulated in terms of transmission and reflection coefficients using simulation software, and an experimental verification is conducted. The electromagnetic characteristic change of the FSS in the presence of mechanical strain or a structural crack is investigated by means of simulation and experiment. Since large-area structures can be covered by deploying FSS, it is possible to detect the location of any cracks.

Practical implementation of piezo‐impedance sensors in monitoring of excavation support structures

Abstract: SUMMARY In the last decade, electromechanical impedance (EMI)-based monitoring technique using piezoceramic (PZT) sensors have been successfully implemented in health monitoring of lab-sized engineering structures. However, its implementation in real life application, such as monitoring underground support structures, has not been done before. In general, the EMI technique utilizes the unique EMI signature where any changes in the signature during the period of monitoring indicate possible damage in the host structure. This paper presents a part of monitoring results of the soil excavation carried out for the construction of new mass road transport (MRT) station in the southern part of Singapore using a PZT-based EMI technique. The MRT site consists of typical clayed soil of varying properties along the depth of excavation. To prevent the soil collapse during excavation, temporary support structures were laid with suitable monitoring systems. The paper presents the results obtained from the PZT sensors and the comparisons with conventional measurement devices. However, there were no damages reported in the structure, and hence the PZT sensors, which were initially aimed to capture possible damages, were used later to capture load variations on the struts due to the surrounding soil. Copyright © 2010 John Wiley & Sons, Ltd.