Sumedha Moharana

Abstract: The performance (sensing/actuating) of a piezotransducer highly depends upon the ability of the bond layer to transfer the stress and strain (through shear lag mechanism) between the transducer and the structure. Therefore, the coupled electromechanical response of the piezotransducer should consider the effect of dynamic behaviour, geometry and composition of the adhesive layer used to bond the transducer patch on the structure. This article presents a new refined analytical model for inclusion of the shear lag effect in modelling of adhesively bonded piezoelectric ceramic (lead zirconate titanate) patches for consideration in the electromechanical impedance technique. The previous models neglected the inertial term in shear lag formulations for simplicity. The present refined model, on the other hand, considers the inertial and the shear lag effects simultaneously, and is therefore more rigorous and complete. In this article, the formulations are first derived for one-dimensional case, and then extended...

Abstract: In the electro-mechanical impedance (EMI) technique, which is based on induced strain actuation through piezoelectric ceramic (PZT) patch, the knowledge of shear stress distribution in the adhesive bond layer between the patch and the host structure is very pertinent for reliable health monitoring of structures. The analytical derivation of continuum based shear lag model covered in this paper aims to provide an improved and more accurate model for shear force interaction between the host structure and the PZT patch (assumed square for simplicity) through the adhesive bond layer, taking care of all the piezo, structural and adhesive effects rigorously and simultaneously. Further, it eliminates the hassle of determining the equivalent impedance of the structure and the actuator separately, as required in the previous models, which was approximate in nature. The results are compared with the previous models to highlight the higher accuracy of the new approach. Based on the new model, a continuum based interaction term has been derived for quantification of the shear lag and inertia effects.

Abstract: This article deals with the analysis of the power consumption in the piezoelectric ceramic patch of lead zirconate titanate and the losses arising from the adhesive bonding with the host structure....

Abstract: During the last two decades, active research has gone into the theoretical and the practical aspects of the electro-mechanical impedance (EMI) technique for structural health monitoring (SHM).This paper reviews the theoretical developments in modelling the force transfer mechanism between the piezoelectric-ceramic (PZT) patch and the host structure pertinent to the EMI technique. The review covers the modelling efforts spanning about last one and a half decades. The models reviewed include the shear lag based model, simplified shear lag model, the refined shear lag model and the continuum shear lag model. The first three listed models ignored the inertia term. The last model, that is the continuum based model, takes care of all the piezo, structural and adhesive effects rigorously and simultaneously. Typical comparisons between the outcomes resulting from the models are discussed.

Abstract: Thank you for downloading properties of concrete. As you may know, people have look hundreds times for their chosen readings like this properties of concrete, but end up in malicious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they juggled with some malicious virus inside their computer. properties of concrete is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library hosts in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Merely said, the properties of concrete is universally compatible with any devices to read.

Abstract: Wind energy is one of the most important renewable energy sources and many countries are predicted to increase wind energy portion of their whole national energy supply to about twenty percent in the next decade. One potential obstacle in the use of wind turbines to harvest wind energy is the maintenance of the wind turbine blades. The blades are a crucial and costly part of a wind turbine and over their service life can suffer from factors such as material degradation and fatigue, which can limit their effectiveness and safety. Thus, the ability to detect damage in wind turbine blades is of great significance for planning maintenance and continued operation of the wind turbine. This paper presents a review of recent research and development in the field of damage detection for wind turbine blades. Specifically, this paper reviews frequently employed sensors including fiber optic and piezoelectric sensors, and four promising damage detection methods, namely, transmittance function, wave propagation, impedance and vibration based methods. As a note towards the future development trend for wind turbine sensing systems, the necessity for wireless sensing and energy harvesting is briefly presented. Finally, existing problems and promising research efforts for online damage detection of turbine blades are discussed.

Abstract: The quantitative scanning electron microscope-backscattered electron (SEM-BSE) image analysis was used to evaluate capillary porosity and pore size distributions in high-strength concretes at early ages. The Powers model for the hydration of cement was applied to the interpretation of the results of image analysis. The image analysis revealed that pore size distributions in concretes with an extremely low water/binder ratio of 0.25 at early ages were discontinuous in the range of finer capillary pores. However, silica-fume-containing concretes with a water/binder ratio of 0.25 had larger amounts of fine pores than did concretes without silica fume. The presence of larger amounts of fine capillary pores in the concretes with silica fume may be responsible for greater autogenous shrinkage in the silica-fume-containing concretes at early ages.

Abstract: The application of smart materials in various fields of engineering has recently become increasingly popular. For instance, the high frequency based electromechanical impedance (EMI) technique employing smart piezoelectric materials is found to be versatile in structural health monitoring (SHM). Thus far, considerable efforts have been made to study and improve the technique. Various theoretical models of the EMI technique have been proposed in an attempt to better understand its behavior. So far, the three-dimensional (3D) coupled field finite element (FE) model has proved to be the most accurate. However, large discrepancies between the results of the FE model and experimental tests, especially in terms of the slope and magnitude of the admittance signatures, continue to exist and are yet to be resolved. This paper presents a series of parametric studies using the 3D coupled field finite element method (FEM) on all properties of materials involved in the lead zirconate titanate (PZT) structure interaction of the EMI technique, to investigate their effect on the admittance signatures acquired. FE model updating is then performed by adjusting the parameters to match the experimental results. One of the main reasons for the lower accuracy, especially in terms of magnitude and slope, of previous FE models is the difficulty in determining the damping related coefficients and the stiffness of the bonding layer. In this study, using the hysteretic damping model in place of Rayleigh damping, which is used by most researchers in this field, and updated bonding stiffness, an improved and more accurate FE model is achieved. The results of this paper are expected to be useful for future study of the subject area in terms of research and application, such as modeling, design and optimization.