scholarly journals Damage Detection of Common Timber Connections Using Piezoceramic Transducers and Active Sensing

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2486 ◽  
Author(s):  
Fang Han ◽  
Jinwei Jiang ◽  
Kai Xu ◽  
Ning Wang
Keyword(s):  
Damage Detection ◽  
Lead Zirconate Titanate ◽  
Failure Modes ◽  
Low Cost ◽  
Energy Levels ◽  
Stress Waves ◽  
Active Sensing ◽  
Timber Structures ◽  
Signal Energy ◽  
Timber Connections

Timber structures have been widely used due to their low-cost and environmental-friendly properties. It is essential to monitor connection damage to ensure the stability and safety of entire timber structures since timber connection damage may induce catastrophic incidents if not detected in a timely manner. However, the current investigations on timber connections focus on mechanical properties and failure modes, and the damage detection of timber connection receives rare attention. Therefore, in this paper, we investigate the damage detection of four common timber connections (i.e., the screw connection, the bolt connection, the decussation connection, and the tooth plate connection) by using the active sensing method. The active sensing method was implemented by using a pair of lead zirconate titanate (PZT) transducers: one PZT patch is used as an actuator to generate stress waves, and the other works as a sensor to detect stress waves after propagating across the timber connection. Based on the wavelet packet energy analysis, the signal energy levels of received stress waves under different damage extent are quantified. Finally, by comparing the signal energy between the intact status and the damage status of the timber connection, we find that the energy attenuates with increasing severity of the connection damage. The experimental results demonstrate that the active sensing method can realize real-time monitoring of timber connection damage, which can guide further investigations.

scholarly journals Structural Health Monitoring of Timber Using Electromechanical Impedance (EMI) Technique

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Fang Han ◽  
Quanjing Zhang ◽  
Chengfeng Wang ◽  
Guangtao Lu ◽  
Jinwei Jiang
Keyword(s):  
Lead Zirconate Titanate ◽  
Low Cost ◽  
Damage Index ◽  
Stress Waves ◽  
Impedance Method ◽  
Size Factor ◽  
Location Factor ◽  
Electromechanical Impedance ◽  
Damage Location ◽  
Impedance Technique

Nowadays, the electromechanical impedance method has been widely used in the field of structural healthy monitoring, especially for the concrete and steel materials. However, the electromechanical impedance studies on damage detection for timber are limited due to the anisotropic and ununiform biomaterial properties. As a low-cost and environment-friendly building material, timber has been widely used in the construction. Thus, it is beneficial to develop electromechanical impedance technique for structural healthy monitoring of timber so as to ensure the stability and safety of the entire timber structures. In this paper, two damage factors, i.e., the damage location factor and the damage size factor of timber specimens are investigated by using the electromechanical impedance method. The method is implemented by using a patch of Lead Zirconate Titanate transducer both as an actuator to generate stress waves and a sensor to detect stress waves after propagating across the timber specimens. Then, the damage index-root mean square deviation is employed to evaluate the damage severity of the timber specimens. The results indicate that the damage index changes consistently with the change of damage location and size factors, and the proposed method using electromechanical impedance technique can efficiently estimate the damage and its severity.

Experimental Research on Damages Detection of Pipeline Structure by Using PZT-Based Waves

2011 ◽  
Author(s):  
Shi Yan ◽  
Binbin He ◽  
Naizhi Zhao
Keyword(s):  
Damage Detection ◽  
Lead Zirconate Titanate ◽  
Smart Materials ◽  
Arrival Time ◽  
Mode Conversion ◽  
Guided Wave ◽  
The Other ◽  
Damage Location ◽  
The Waves ◽  
Peak Value

Pipeline structure may generate damages during its service life due to the influence of environment or accidental loading. The damages need to be detected and repaired if they are severe enough to influence the transportation work. Non-destructive detection using smart materials combined with suitable diagonal algorithms are widely used in the field of structural health monitoring (SHM). Piezoelectric ceramics (such as Lead Zirconate Titanate, PZT) is one of the smart materials to be applied in the SHM due to the piezoelectric effect. So far, the PZT-based wave method is widely used for damage detection of structures, in particular, pipeline structures. A series of piezoelectric patches are bonded on the surface of the pipeline structure to monitor the damages such as local crack or effective area reduction due to corrosion by using diagonal waves. The damage of the pipeline structure can be detected by analysis of the received diagonal waves which peak value, phase, and arriving time can be deferent from the health ones. The response of the diagonal wave is not only correlated to the damage location through estimation of the arrival time of the wave peak, but also associated with the peak value of the wave for the reduction of wave energy as the guided wave passing through the damages. Therefore, the presence of damages in the pipeline structure can be detected by investigating the parameter change of the guided waves. The change of the wave parameters represents the attenuation, deflection and mode conversion of the waves due to the damages. In addition, the guided wave has the ability of quick detecting the damage of the pipeline structure and the simplicity of generating and receiving detection waves by using PZT patches. To verify the proposed method, an experiment is designed and tested by using a steel pipe bonded the PZT patches on the surface of it. The PZT patches consist of an array to estimate the location and level of the damage which is simulated by an artificial notch on the surface of the structure. The several locations and deep heights of the notches are considered during the test. A pair of the PZT patches are used at the same time as one is used as an actuator and the other as a sensor, respectively. A tone burst of 5 cycles of wave shape is used during the experiment. A wave generator is applied to create the proposed waves, and the waves are amplified by an amplifier to actuate the PZT patch to emit the diagonal waves with appropriately enough energy. Meanwhile, the other PZT patch is used as a sensor to receive the diagonal signals which contain the information of the damages for processing. For data processing, an index of root mean square deviation (RMSD) of the received data is used to estimate the damage level by compare of the data between the damaged and the health peak valves of the received signals. The time reversal method which aimed at increasing the efficiency of the detection is also used to detect the damage location by estimating the arrival time of the reflected wave passing with a certain velocity. The proposed method experimentally validates that it is effective for application in damage detection of pipeline structure.

Seismic Performance of RC Short Columns Strengthened with BFRP

2013 ◽  
Vol 351-352 ◽  
pp. 1532-1536 ◽  
Author(s):  
Bin Ding ◽  
Li Jun Ouyang ◽  
Zhou Dao Lu ◽  
Wei Zhen Chen
Keyword(s):  
Seismic Performance ◽  
Failure Modes ◽  
Low Cost ◽  
Economic Cost ◽  
Shear Capacity ◽  
Good Prospect ◽  
Loading Test ◽  
Fiber Reinforced Plastic ◽  
Short Columns ◽  
Reinforced Plastic

BFRP has excellent strength, durability, thermal properties and economic cost. To test seismic performance of short columns strengthened with BFRP. Low cyclic loading test was conducted on one comparative short column and two RC short columns strengthened with BFRP. The test shows that short columns warped by BFRP show excellent failure modes, shear capacity, ductility and energy dissipation. As a new fiber reinforced plastic, BFRP has a good prospect in the area of seismic strengthening for its low cost and comprehensive mechanical properties.

Porphyrin doping of dichloride-bis(5,7-dichloroquinolin-8-olato)tin(IV) complex for electroluminescence

2013 ◽  
Vol 17 (05) ◽  
pp. 351-358 ◽  
Author(s):  
Mohammad Janghouri ◽  
Ezeddin Mohajerani ◽  
Mostafa M. Amini ◽  
Naser Safari
Keyword(s):  
Molecular Orbital ◽  
Light Emitting Diode ◽  
Low Cost ◽  
Energy Levels ◽  
Orbital Energy ◽  
Homogeneous Layer ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Fundamental Structure ◽  
Organic Light

A method for obtaining red emission from an organic-light emitting diode has been developed by dissolving red and yellow dyes in a common solvent and thermally evaporating the mixture in a single furnace. Dichlorido-bis(5,7-dichloroquinolin-8-olato)tin(IV) complex ( Q2SnCl2 , Q = 5,7-dichloro-8-hydroxyquinoline) has been synthesized for using as a fluorescent material in organic light-emitting diodes (OLEDs). The electronic states HOMO (Highest Occupied Molecular Orbital)/LUMO (Lowest Occupied Molecular Orbital) energy levels explored by means of cyclic voltammetry measurements. A device with fundamental structure of ITO/PEDOT:PSS (55nm)/PVK (90nm)/ Q2SnCl2/Al (180nm) was fabricated and its electroluminescence performance at various thicknesses of light emitting layer (LEL) of Q2SnCl2 is reported. By following this step, an optimal thickness for the doping effect was also identified and explained. Finally a device with fundamental structure of ITO/PEDOT:PSS (55nm)/PVK (90nm)/meso-tetraphenylporphyrin (TPP): Q2SnCl2 (75nm)/ Al (180nm) was fabricated and its electroluminescence performance at various concentrations of dye has been investigated. It is shown that this new method is promising candidate for fabrication of low cost OLEDs at more homogeneous layer.

scholarly journals Photocatalytic Overall Water Splitting by SrTiO3 with Surface Oxygen Vacancies

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2572
Author(s):  
Yanfei Fan ◽  
Yan Liu ◽  
Hongyu Cui ◽  
Wen Wang ◽  
Qiaoyan Shang ◽  
...  
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Oxygen Vacancies ◽  
Low Cost ◽  
Energy Levels ◽  
Light Response ◽  
Hydrogen Energy ◽  
Surface Oxygen ◽  
Carbon Reduction ◽  
Overall Water Splitting

Strontium Titanate has a typical perovskite structure with advantages of low cost and photochemical stability. However, the wide bandgap and rapid recombination of electrons and holes limited its application in photocatalysis. In this work, a SrTiO3 material with surface oxygen vacancies was synthesized via carbon reduction under a high temperature. It was successfully applied for photocatalytic overall water splitting to produce clean hydrogen energy under visible light irradiation without any sacrificial reagent for the first time. The photocatalytic overall water splitting ability of the as-prepared SrTiO3-C950 is attributed to the surface oxygen vacancies that can make suitable energy levels for visible light response, improving the separation and transfer efficiency of photogenerated carriers.

scholarly journals Prefabricated Urban Underground Utility Tunnels: A Case Study on Mechanical Behaviour with Strain Monitoring and Numerical Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yonggang Xiao ◽  
Jubing Zhang ◽  
Jie Cao ◽  
Changhong Li
Keyword(s):  
Numerical Simulation ◽  
Working Conditions ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Low Cost ◽  
Side Wall ◽  
Operating Conditions ◽  
Land Occupation ◽  
Depth Analysis ◽  
Simulation Results

The prefabricated urban utility tunnels (UUTs) have many advantages such as short construction period, low cost, high quality, and small land occupation. However, there is still a lack of in-depth analysis of the mechanical performance of the prefabricated urban utility tunnel (UUT) structure with bolted connections under different working conditions. In this paper, the force performance of a prefabricated UUT in Tongzhou District, Beijing, was studied under different working conditions using two methods: field monitoring and numerical simulation. The multichannel strain monitor was used for monitoring, and the internal wall concrete and bolt strain change data under the two conditions of installation and backfill were obtained. Combined with the construction process of the UUTs, a three-dimensional numerical model was established by COMSOL, where the build-in bolt assembly was used to simulate the longitudinal connection of the tunnel. The simulation results were compared with the measured data to verify the rationality of the computational model. The simulation results showed that the concrete and bolts on the inner wall of the tunnel work well under the two conditions of installation and backfilling; The deformation of the top plate of the prefabricated tunnel was approximately parabolic, with the largest vertical displacement (0.37 mm) in the middle and the most sensitive to the vertical load in the central part of the roof. The central portion of the side wall had the largest displacement (0.17 mm) in the inner concave. The tensile stress of bolt 3 increased the most (30.75 MPa) but was still much smaller than the yield strength of the bolt. The concrete and bolts of the UUT were found to work well through force analysis under operating conditions. In conclusion, analysis of structural forces and deformation failure modes will help design engineers understand the basic mechanisms and select the appropriate UUT structure.

Damage detection in concrete structures using a simultaneously activated multi-mode PZT active sensing system: numerical modelling

2013 ◽  
Vol 10 (11) ◽  
pp. 1451-1468 ◽  
Author(s):  
Costas P. Providakis ◽  
Kalliopi D. Stefanaki ◽  
Maristella E. Voutetaki ◽  
Yiannis Tsompanakis ◽  
Maria Stavroulaki
Keyword(s):  
Numerical Modelling ◽  
Damage Detection ◽  
Concrete Structures ◽  
Active Sensing ◽  
Sensing System ◽  
Multi Mode

scholarly journals Damage Detection in Fiber-Reinforced Foamed Urethane Composite Railway Bearers Using Acoustic Emissions

2020 ◽  
Vol 5 (6) ◽  
pp. 50 ◽  
Author(s):  
Pasakorn Sengsri ◽  
Chayut Ngamkhanong ◽  
Andre Luis Oliveira de Melo ◽  
Mayorkinos Papaelias ◽  
Sakdirat Kaewunruen
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Failure Modes ◽  
Acoustic Emissions ◽  
Numerical Data ◽  
Composite Beams ◽  
Fiber Reinforced ◽  
Traffic Demand ◽  
Three Point Bending ◽  
Railway Industry

To a certain degree, composite railway sleepers and bearers have been recently employed as a replacement for conventional timber sleepers. Importantly, attributed to the rise in traffic demand, structural health monitoring of track structural members is essential to improve the maintenance regime and reduce risks imposed by any structural damage. A potential modern technique for detecting damage in railway components by using energy waves is called acoustic emission (AE). This technique has been widely used for concrete structures in other engineering applications, but the application for composites is relatively limited. Recently, fiber-reinforced foamed urethane (FFU) composites have been utilized as railway sleepers and bearers for applications in the railway industry. Neither does a design standard exist, nor have the inspection and monitoring criteria been properly established. In this study, three-point bending tests were performed together with using the AE method to detect crack growth in FFU composite beams. The ultimate state behaviors are considered to obtain the failure modes. This paper is thus the world’s first to focus on damage detection approaches for FFU composite beams using AE technology, additionally identifying the load-deflection curves of the beams. According to the experimental results, it is apparent that the failure modes of FFU composite beams are likely to be in brittle modes. Through finite element method, the results were in good agreement with less than 0.14% discrepancy between the experimental and numerical data. The attractive insights into an alternative technique for damage assessment of the composite components will help railway engineers to establish structural monitoring guidelines for railway composite sleepers and bearers.

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