Papers by Keyword: Structural Health Monitoring (SHM)

Abstract: This study investigates the vibration characteristics of 3D-printed polylactic acid (PLA) cantilever beams using a hybrid analytical–numerical–experimental framework. Two low-cost sensing techniques—an MPU6050 accelerometer and a GoPro Hero10 vision-based system—are systematically evaluated against analytical Euler–Bernoulli and numerical ANSYS models. The analytical and numerical approaches show strong consistency for the first three natural frequencies (Mode 1: 10.22–10.31 Hz; Mode 2: 64.04–64.58 Hz; Mode 3: 179.34–180.95 Hz). Experimentally, the GoPro accurately captures the first mode (10.5 Hz), while the accelerometer successfully detects the first two modes but deviates in the third mode due to nonlinear mass-loading and sensor–structure coupling effects. The findings highlight both the capability and limitations of low-cost SHM tools and provide new insights into nonlinear behaviour in lightweight polymeric beams. The novelty of this work lies in its multi-method validation and explicit quantification of nonlinear deviations, offering a practical framework for accessible vibration-based monitoring.

Abstract: Infrastructure development serves as an indicator of a country’s social and economic growth. Bridges are the key assets of infrastructure projects that are built for a design life of more than 50 years. During their lifespan, they are subjected to defects and deterioration due to physical changes, chemical attacks, internal reactions, etc. that are required to be addressed by timely inspection and monitoring. Inspection practices have a great impact on maintenance planning and decision-making. Since bridges are public infrastructure the budget allocated to their repair and maintenance is limited. Therefore, there arises a need for accurate, measurable, reliable, and cost-effective technologies for bridge health monitoring that can be incorporated into decision-making tools to prioritize repair and maintenance strategies. In recent years the trend has shifted from visual inspection to IoT-based condition assessment. This technique evaluates the bridge’s global and localized, and static and dynamic responses. However, there is a need to develop a systematic structure for a bridge health monitoring system, standardizing the data acquisition, processing, and transmission from a group of sensors to evaluate the existing condition of the bridge. This study proposes a conceptual IoT-based framework for structural health monitoring of existing reinforced concrete bridges for informed decision-making along with development of data acquisition system.

Abstract: Nowadays, the demand for glass fibre-reinforced polymers (GFRPs) has increased in the industry owing to their low weight, high strength, corrosion resistance and low cost compared with other fibre-reinforced polymer composites. However, GFRP is anisotropic material with low interlaminar strength where the damage can occur without warning. Integrating a real-time damage detection process can mitigate this problem. Therefore, this paper presents the initial fabrication of an embedded capacitive sensor into the GFRP by using conductive electrodes inbetween its layers. To form the sensing electrodes, glass fibre yarns were coated with conductive material and braided into the fibregalss woven fabric. Two coating methods were considered to form embedded electrodes in this work which include aerosol spray coatings that were carbon based and gold-based physical vapour deposition, (PVD). It has been shown that spray coating has a weak bond and the carbon particles disperse during the molding process. In the PVD technique the nanoparticle (Au) distributed uniformly along the fibres and has a good resistance (≈100Ω). The capacitive sensor based on gold coating was exaimined using a three point bending test which demonstrate linear response toward the flexural load with a sensitivity of 25.1 fF/N.

Abstract: This research focuses on the electromechanical strain-sensing behaviour of steel wires on the fiber and composites scale. The electromechanical properties are investigated by using a uniaxial fiber tensile test with a simultaneous electrical resistance measurement. Further, this work conducts a comprehensive stress analysis of textile reinforced concrete (TRC) specimen in quasistatic and dynamic tensile tests by using integrated steel wires in a textile 3D-weaving reinforcement as piezoresistive in-situ-sensors. The results are compared to optical strain measurements using digital image correlation (DIC). The acquisition and analysis of the electrical resistance changes of the steel wire sensors enable an in-situ stress analysis as well as a better understanding of the mechanical response of the TRC specimen under different loading scenarios.

Abstract: High-rise construction typically implies a multi-storey structure approximately between forty to hundred and twenty meters tall (approximately twelve to forty storeys). On the other hand, composite materials are those made from two or more constituents generally with considerably dissimilar physical or chemical compositions. The focal point in this paper is in-particular on high-rise construction and whether or not composite materials’ structural integrity, and long-term sustainability, is comparable to that of a traditional building. To assess the composite materials’ structural integrity, Structural Health Monitoring (SHM) will also be utilised. While, composites possess different characteristics from those common to traditional materials; the universal purpose of producing such materials is to produce matters, which are stronger, lighter, and commonly less expensive. Generally, in construction, the composite materials typically include geo-polymers, fiber-reinforced concrete and others. For high-rise construction, these composite materials require to bear a variety of demanding conditions, including high winds and seismic conditions, which are important design factors for such structures. Nevertheless, a particular benefit of composite materials for high rise construction is their overall ability to maintain structural integrity despite their lack of conventional composition. The composite materials are traditionally utilised for high-rise buildings in order to reinforce the overall structural integrity. Accordingly, this paper will also include a number of case studies to support the ever-increasing utilization of composite materials for high-rise construction.

Abstract: The aim of this paper was to carry out numerical simulations of structural health monitoring applications for plate structures using the boundary element method (BEM). The fundamental symmetric Lamb mode (S0) is chosen for the SHM applications. The propagation, reflection and diffraction of the S0 mode Lamb wave are modelled using a boundary element formulation based on the plane stress theory. Piezoelectric (PZT) actuators are mounted on plate surfaces to excite the S0 mode wave. A semi-analytical method is adopted to couple the PZT actuators and the host plate. Numerical results show that BEM is a very efficient simulation method for the structural health monitoring of plates.

Abstract: A novel procedure for installation of PZT sensors on composites is developed. The procedure is shown, through extensive tests, to be reliable, repeatable and repairable. The integrity of the bonded sensors are assessed following the RTCA DO-160 Environmental conditions and test procedures for airborne equipment. The developed bonding film has been tested on both thermoset and thermoplastic coupons and compared co-cured and secondary bonded sensors with epoxy.

Abstract: Airworthiness authorities require that composite materials in primary structures must be undamaged all in-service life long, resulting in an oversizing of structural components and in a general increasing of weight. To allow structures working in presence of damages but showing an acceptable residual strength, in recent years a significant interest has been pointed out in the capability of ultrasonic guided waves as candidate tool for Structural Health Monitoring (SHM) of composites. The continuous assessment of the structural integrity, that can be accomplished by means of SHM systems, would provide, in fact, a less-conservative design and significant benefits in repair operations. In this work, a description of two numerical techniques based on Finite Element Method (FEM) for the simulation of Lamb wave propagation in a damaged Glass Fibre Reinforced Polymer composite winglet is presented. The interaction between damage and guided-waves has been investigated under two central frequencies: 100 kHz and 150 kHz. Root Mean Square Deviation Damage Index has been used to compare the baseline signals (achieved under the pristine configuration) and the respective signals achieved under the impacted/damaged one. Numerical models have been assessed against an experimental tests campaign.

Abstract: Detectability of damage using Lamb waves depends on many factors such as size and severity of damage, attenuation of the wave and distance to the transducers. This paper presents a detectability model for pitch-catch sensors configuration for structural health monitoring (SHM) applications. The proposed model considers the physical properties of lamb wave propagation and is independent of damage detection algorithm, which provides a generic solution for probability of detection. The applicability of the model in different environmental and operational conditions is also discussed.

Abstract: A hybrid piezoelectric (PZT)/fibre optic diagnostic system has been developed for damage detection in built up composite structures. The hybrid system uses PZT transducers to actuate the structure and fibre optic (FO) sensors to capture the propagating wave. The diagnostic system will then have the advantages of both PZT and FO sensors. The applicability of the system is then tested for detecting an artificial damage at a skin/stiffener interface of a thick composite structure. The response of the FO sensors is then compared to PZT sensors and presented.