New refined analytical models for various bonding conditions of an adhesively bonded smart PZT transducer using the EMI technique

2021 ◽  
Vol 30 (12) ◽  
pp. 125015
Author(s):  
Aditya Parpe ◽  
T Jothi Saravanan
Keyword(s):  
Analytical Model ◽  
Lead Zirconate Titanate ◽  
Structural Damage ◽  
Experimental Studies ◽  
Protective Layer ◽  
Adhesive Bond ◽  
Analytical Models ◽  
Bonding Condition ◽  
Bond Layer ◽  
Host Structure

Abstract The electro-mechanical impedance (EMI) technique has emerged as a cost-effective and non-destructive technique to detect the possible damages in the structure using a piezoelectric transducer, especially, lead zirconate titanate (PZT). The adhesive bond layer plays an important role in the PZT patch-host structure interaction for monitoring structural damage. Two bonding conditions are investigated in this research paper. Primarily, the debonding phenomenon of the adhesive bond layer may misinterpret the EMI response on the damage caused in structure. Subsequently, the investigation included the protective layer at the top of the PZT transducer to avoid sensor degradation. However, the analytical models developed so far have not considered a protective layer at the top of the PZT transducer. This paper presents the novel two-dimensional (2D) analytical model for incorporating debonding concepts and the new refined 2D analytical model to include a protective layer in the study of surface-bonded PZT transducers. The proposed analytical models are verified with the experimental studies. The experimental and analytical results show good agreement, which confirms the effectiveness of the new models. This paper also incorporated the effect of each bonding condition for monitoring structural damage by implementing the EMI technique. For the simulation, the numerical investigations on the PZT transducer bonded on the metallic (aluminum and steel) and concrete blocks are performed using coupled field analysis through finite element (FE) modeling. It is found that each bonding condition has influenced the resulting signatures. The signatures obtained from developed theoretical models and numerical simulations using three-dimensional FE models for each bonding condition are compared to highlight the influence on structural damage detection. The trend of signatures is found to be matching satisfactory. Several parametric studies have been conducted to show the efficacy of the new refined model with a protective layer. It considers the different input properties of an adhesive layer, host structure, and temperature conditions. The influence of debonding of the protective layer is also studied, and the obtained results support the need for a protective layer in the models.

Finite Element Modeling and Effect of Electrical/Mechanical Parameters on Electromechanical Impedance Damage Detection

2009 ◽  
Author(s):  
Daniel J. Kitts ◽  
Andrei N. Zagrai
Keyword(s):  
Finite Element ◽  
Structural Damage ◽  
Active Material ◽  
Piezoelectric Element ◽  
Adhesive Bond ◽  
Structural Element ◽  
Structural Dynamic ◽  
Electromechanical Impedance ◽  
Sensor Structure ◽  
Host Structure

Electromechanical Impedance (EMI) is a popular SHM technique, which has found applications in many fields of engineering: mechanical, aerospace, civil and others. Active elements of the technique are piezoelectric wafer active sensors bonded or embedded into a structural element. EMI detection of structural damage is achieved by comparing high frequency structural dynamic signatures reflected in the electromechanical impedance measured at the sensor terminals. Over a past decade, substantial efforts have been devoted to analytical and numerical modeling of various aspects of EMI method. The majority of prior studies focused on fundamental understanding of the sensor transduction mechanism and sensor-structure interaction. Although basic principles of the EMI method are now well understood, modeling of practical structural diagnostic scenarios remains challenging. This contribution expands current modeling efforts in the EMI SHM by considering issues related to energy dissipation in piezoelectric sensor and host structure, as well as its effect on detectability of structural damage. Piezoelectric element and a host structure were modeled using Comsol® Multiphysics finite element package. The finite element implementation allowed for considering contributions of active material, adhesive bond and structural damage. These contributions were studied parametrically for various model settings including mechanical and electrical losses. The study shows that sensor position may directly control damage manifestation in EMI signature; effect of adhesive bond thickness is comparable in magnitude to the effect of bond stiffness; influence of piezoelectric mechanical losses on the impedance signature is different for damaged and undamaged cases.

scholarly journals Bond Degradation and Residual Flexural Capacity of Corroded RC Beams

2021 ◽  
Author(s):  
Hao Wu
Keyword(s):  
Bond Strength ◽  
Analytical Model ◽  
Experimental Studies ◽  
Reinforced Concrete Beam ◽  
Analytical Models ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Damage State ◽  
Strain Compatibility ◽  
Bond Degradation

An analytical model is developed to predict the residual flexural capacity of corroded RC members. This was established by first developing an analytical model to calculate the residual bond strength at steel-concrete interface. The bond model is then implemented within the framework of the moment resistance method, and a new strain compatibility analysis was developed: to account the analysis of a corroded reinforced concrete beam, to incorporate dependence of the bond response on the stress strain and damage state of the concrete and steel. Method for calculating flexural capacity of corroded RC beams is then proposed, which is based on flexural analysis of RC beams that considers the effect of bond degradation. The predicted results of these models correlated very well with results observed in various experimental studies. This indicates that those developed analytical models tend to estimate conservatively the residual bond strength and flexural capacity of corroded RC beams. .

scholarly journals Analytical development and optimization of a graphene–solution interface capacitance model

2014 ◽  
Vol 5 ◽  
pp. 603-609 ◽  
Author(s):  
Hediyeh Karimi ◽  
Rasoul Rahmani ◽  
Reza Mashayekhi ◽  
Leyla Ranjbari ◽  
Amir H Shirdel ◽  
...  
Keyword(s):  
Analytical Model ◽  
Field Effect Transistors ◽  
Experimental Studies ◽  
Analytical Models ◽  
Quantum Capacitance ◽  
Percentage Error ◽  
Fermi Velocity ◽  
Solution Interface ◽  
Analytical Development ◽  
Capacitance Model

Graphene, which as a new carbon material shows great potential for a range of applications because of its exceptional electronic and mechanical properties, becomes a matter of attention in these years. The use of graphene in nanoscale devices plays an important role in achieving more accurate and faster devices. Although there are lots of experimental studies in this area, there is a lack of analytical models. Quantum capacitance as one of the important properties of field effect transistors (FETs) is in our focus. The quantum capacitance of electrolyte-gated transistors (EGFETs) along with a relevant equivalent circuit is suggested in terms of Fermi velocity, carrier density, and fundamental physical quantities. The analytical model is compared with the experimental data and the mean absolute percentage error (MAPE) is calculated to be 11.82. In order to decrease the error, a new function of E composed of α and β parameters is suggested. In another attempt, the ant colony optimization (ACO) algorithm is implemented for optimization and development of an analytical model to obtain a more accurate capacitance model. To further confirm this viewpoint, based on the given results, the accuracy of the optimized model is more than 97% which is in an acceptable range of accuracy.

scholarly journals Bond Degradation and Residual Flexural Capacity of Corroded RC Beams

2021 ◽  
Author(s):  
Hao Wu
Keyword(s):  
Bond Strength ◽  
Analytical Model ◽  
Experimental Studies ◽  
Reinforced Concrete Beam ◽  
Analytical Models ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Damage State ◽  
Strain Compatibility ◽  
Bond Degradation

An analytical model is developed to predict the residual flexural capacity of corroded RC members. This was established by first developing an analytical model to calculate the residual bond strength at steel-concrete interface. The bond model is then implemented within the framework of the moment resistance method, and a new strain compatibility analysis was developed: to account the analysis of a corroded reinforced concrete beam, to incorporate dependence of the bond response on the stress strain and damage state of the concrete and steel. Method for calculating flexural capacity of corroded RC beams is then proposed, which is based on flexural analysis of RC beams that considers the effect of bond degradation. The predicted results of these models correlated very well with results observed in various experimental studies. This indicates that those developed analytical models tend to estimate conservatively the residual bond strength and flexural capacity of corroded RC beams. .

scholarly journals Novel Structure and Thermal Design and Analysis for CubeSats in Formation Flying

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 150
Author(s):  
Yeon-Kyu Park ◽  
Geuk-Nam Kim ◽  
Sang-Young Park
Keyword(s):  
Analytical Model ◽  
Formation Flying ◽  
Thermal Environment ◽  
Thermal Analyses ◽  
Thermal Design ◽  
Analytical Models ◽  
Test Results ◽  
Solar Panels ◽  
Novel Structure ◽  
Micro Propulsion

The CANYVAL-C (CubeSat Astronomy by NASA and Yonsei using a virtual telescope alignment for coronagraph) is a space science demonstration mission that involves taking several images of the solar corona with two CubeSats—1U CubeSat (Timon) and 2U CubeSat (Pumbaa)—in formation flying. In this study, we developed and evaluated structural and thermal designs of the CubeSats Timon and Pumbaa through finite element analyses, considering the nonlinearity effects of the nylon wire of the deployable solar panels installed in Pumbaa. On-orbit thermal analyses were performed with an accurate analytical model for a visible camera on Timon and a micro propulsion system on Pumbaa, which has a narrow operating temperature range. Finally, the analytical models were correlated for enhancing the reliability of the numerical analysis. The test results indicated that the CubeSats are structurally safe with respect to the launch environment and can activate each component under the space thermal environment. The natural frequency of the nylon wire for the deployable solar panels was found to increase significantly as the wire was tightened strongly. The conditions of the thermal vacuum and cycling testing were implemented in the thermal analytical model, which reduced the differences between the analysis and testing.

scholarly journals Opportunistic Large Array Propagation Models: A Comprehensive Survey

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4206
Author(s):  
Farhan Nawaz ◽  
Hemant Kumar ◽  
Syed Ali Hassan ◽  
Haejoon Jung
Keyword(s):  
Energy Efficient ◽  
Large Scale ◽  
Performance Metrics ◽  
Experimental Studies ◽  
Cooperative Transmission ◽  
Analytical Models ◽  
Future Research ◽  
Large Array ◽  
Propagation Models ◽  
Comprehensive Survey

Enabled by the fifth-generation (5G) and beyond 5G communications, large-scale deployments of Internet-of-Things (IoT) networks are expected in various application fields to handle massive machine-type communication (mMTC) services. Device-to-device (D2D) communications can be an effective solution in massive IoT networks to overcome the inherent hardware limitations of small devices. In such D2D scenarios, given that a receiver can benefit from the signal-to-noise-ratio (SNR) advantage through diversity and array gains, cooperative transmission (CT) can be employed, so that multiple IoT nodes can create a virtual antenna array. In particular, Opportunistic Large Array (OLA), which is one type of CT technique, is known to provide fast, energy-efficient, and reliable broadcasting and unicasting without prior coordination, which can be exploited in future mMTC applications. However, OLA-based protocol design and operation are subject to network models to characterize the propagation behavior and evaluate the performance. Further, it has been shown through some experimental studies that the most widely-used model in prior studies on OLA is not accurate for networks with networks with low node density. Therefore, stochastic models using quasi-stationary Markov chain are introduced, which are more complex but more exact to estimate the key performance metrics of the OLA transmissions in practice. Considering the fact that such propagation models should be selected carefully depending on system parameters such as network topology and channel environments, we provide a comprehensive survey on the analytical models and framework of the OLA propagation in the literature, which is not available in the existing survey papers on OLA protocols. In addition, we introduce energy-efficient OLA techniques, which are of paramount importance in energy-limited IoT networks. Furthermore, we discuss future research directions to combine OLA with emerging technologies.

The effects of geometric offsets on the dynamic responses of a Scott—Russell amplifying mechanism with flexible hinges

2009 ◽  
Vol 223 (10) ◽  
pp. 2413-2423 ◽  
Author(s):  
C-M Chen ◽  
R-F Fung
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Dynamic Responses ◽  
Analytical Models ◽  
Dynamic Equations ◽  
Magnification Factor ◽  
Flexure Hinges ◽  
Magnification Factors ◽  
Straight Line ◽  
Deviation Factor

The dynamic equations of a micro-positioning Scott—Russell (SR) mechanism associated with two flexible hinges and an offset are developed to calculate output responses. Both rigid and flexible hinges are considered to explore the results. The main features in the kinematics of the SR mechanism are its displacement amplification and straight-line motion, which are widely needed in practical industries. The manufacturing inaccuracy of the SR mechanism definitely causes geometric offsets of flexure hinges, and affects displacement amplification and straight-line output motion. Analytical models based on kinematics and Hamilton's principle are derived to explore the variation of linearity ratio, magnification factor, and deviation factor due to various offsets and link lengths. From numerical simulations for the SR mechanism with various offsets of flexible hinges in the conditions of different link lengths, it is found that offsets of flexure hinges obviously affect the amplifying factor and linearity ratio, and appear to dominate the changes of magnification factors. Moreover, an analytical model is also used to predict magnification factors due to various offsets. Finally, some conclusions concerning the effects of offset on the performance of the SR mechanism are drawn.

Modeling of residual stresses by correlating surface topography in machining of AISI 52100 steel

2021 ◽  
pp. 1-26
Author(s):  
Chao Liu ◽  
Yan He ◽  
Yufeng Li ◽  
Yulin Wang ◽  
Shilong Wang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cutting Force ◽  
Surface Topography ◽  
Analytical Model ◽  
Analytical Models ◽  
Workpiece Surface ◽  
Dynamic Cutting Force ◽  
Intermittent Cutting ◽  
Effect Of Surface

Abstract The residual stresses could affect the ability of components to bear loading conditions and also the performance. The researchers considered workpiece surface as a plane and ignored the effect of surface topography induced by the intermittent cutting process when modeling residual stresses. The aim of this research develops an analytical model to predict workpiece residual stresses during intermittent machining by correlating the effect of surface topography. The relative motions of tool and workpiece are analyzed for modeling thermal-mechanical and surface topography. The influence of dynamic cutting force and thermal on different positions of surface topography is also considered in analytical model. Then the residual stresses model with the surface topography effect can be developed in intermittent cutting. The analytical models of dynamic cutting force, surface topography and residual stresses are verified by the experiments. The variation trend of evaluated values of the residual stress of workpiece is basically consistent with that of measured values. The compressive residual stress of workpiece surface in highest point of the surface topography are higher than that in the lowest point.

An analytical model for predicting the shear strength of unsaturated soils

2022 ◽  
pp. 1-57
Author(s):  
Tuan A. Pham ◽  
Melis Sutman
Keyword(s):  
Shear Strength ◽  
Analytical Model ◽  
Unsaturated Soils ◽  
High Performance ◽  
Micromechanical Model ◽  
Experimental Studies ◽  
Stress Equilibrium ◽  
Proposed Model ◽  
New Equation ◽  
Multi Phase

The prediction of shear strength for unsaturated soils remains to be a significant challenge due to their complex multi-phase nature. In this paper, a review of prior experimental studies is firstly carried out to present important pieces of evidence, limitations, and some design considerations. Next, an overview of the existing shear strength equations is summarized with a brief discussion. Then, a micromechanical model with stress equilibrium conditions and multi-phase interaction considerations is presented to provide a new equation for predicting the shear strength of unsaturated soils. The validity of the proposed model is examined for several published shear strength data of different soil types. It is observed that the shear strength predicted by the analytical model is in good agreement with the experimental data, and get high performance compared to the existing models. The evaluation of the outcomes with two criteria, using average relative error and the normalized sum of squared error, proved the effectiveness and validity of the proposed equation. Using the proposed equation, the nonlinear relationship between shear strength, saturation degree, volumetric water content, and matric suction are observed.

scholarly journals Determination of the time of ignition of plant raw under the high temperature of the radiation panel

2020 ◽  
Vol 11 (3) ◽  
Author(s):  
V. V. Lomaha ◽  
O. Yu. Tsapko ◽  
Yu. V. Tsapko ◽  
O. P. Bondarenko
Keyword(s):  
High Temperature ◽  
Fire Protection ◽  
Effective Means ◽  
Experimental Studies ◽  
Fire Retardant ◽  
Protective Layer ◽  
Thermal Action ◽  
Environmental Safety ◽  
Wood Products ◽  
Operational Parameters

Reducing the fire prevention of timber is not only an economic task, but also has a social and environmental focus. From economic, technological and environmental perspective, an important problem in ensuring the viability and safe operation of construction sites is the development of fire-retardant coatings for wooden structures. The construction is increasingly looking for new highly effective means of fire protection of wood and wood products which should not only ensure the standardized fire resistance of wood, but also to maintain its operational parameters to solve environmental safety and durability. Studies of the effect of the radiation panel on the ignition of the wood sample have set the parameters of the flame ignition, which makes it possible to influence this process. It is proved that they consist in the formation of a layer of organic material on the surface, which provides heating to a critical temperature, when the intensive decomposition of the material begins with the release of the required amount of combustible gases and their ignition. This makes it possible to determine the effect of fire protection and the properties of protective compositions on the process of slowing down the rate of burning of wood. Experimental studies have confirmed that the untreated sample of wood, under the thermal action of the radiation panel has taken up, the flames spread over the entire surface, which led to its combustion. The application of a fire retardant varnish under the influence of temperature leads to a layer of foam coke and inhibition of heat transfer of high-temperature flame to the material and its ignition. Thanks to this, it became possible to determine the conditions for changing the parameters of combustion and braking during fire protection of wood, by forming a barrier for thermal conductivity. Thus, there is reason to argue for the possibility of directional control of the processes of fire protection of wood by the use of fireproof coatings that can form a protective layer on the surface of the material, which slows down the rate of burning of wood.

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