The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Kamlesh Jangid - One of the best experts on this subject based on the ideXlab platform.
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magnetic Saturation Zone model for two semipermeable cracks in magneto electro elastic medium
International Journal for Computational Methods in Engineering Science and Mechanics, 2018Co-Authors: Kamlesh JangidAbstract:ABSTRACTExtension of the PS model (Gao et al. [1]) in piezoelectric materials and the SEMPS model (Fan and Zhao [2]) in MEE materials, is proposed for two semi-permeable cracks in a MEE medium. It is assumed that the magnetic yielding occurs at the continuation of the cracks due to the prescribed loads. We have model these crack continuations as the Zones with cohesive Saturation limit magnetic induction. Stroh's formalism and complex variable techniques are used to formulate the problem. Closed form analytical expressions are derived for various fracture parameters. A numerical case study is presented for BaTiO3 − CoFe2O4 ceramic cracked plate.
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Strip-coalesced interior Zone model for two unequal collinear cracks weakening piezoelectric media
Applied Mathematics and Mechanics, 2014Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:In this paper, a mathematical strip-Saturation model is proposed for a poled transversely isotropic piezoelectric plate weakened by two impermeable unequal-collinear hairline straight cracks. Remotely applied in-plane unidirectional electromechanical loads open the cracks in mode-I such that the Saturation Zone developed at the interior tips of cracks gets coalesced. The developed Saturation Zones are arrested by distributing over their rims in-plane normal cohesive electrical displacement. The problem is solved using the Stroh formalism and the complex variable technique. The expressions are derived for the stress intensity factors (SIFs), the lengths of the Saturation Zones developed, the crack opening displacement (COD), and the energy release rate. An illustrative numerical case study is presented for the poled PZT-5H ceramic to investigate the effect of prescribed electromechanical loads on parameters affecting crack arrest. Also, the effect of different lengths of cracks on the SIFs and the local energy release rate (LERR) has been studied. The results obtained are graphically presented and analyzed.
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Strip electro-mechanical yielding model for piezoelectric plate cut along two equal collinear cracks
Applied Mathematical Modelling, 2013Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:Abstract The multiple-crack problems for piezoelectric ceramics till now have not yet address the crack opening arrest problem. The present work addresses this paucity. A 2-D strip-electro-mechanical yielding model is proposed for a transversely isotropic piezoelectric media weakened by two internal equal collinear straight cracks. The infinite boundary is prescribed with combined uniform constant in-plane mechanical and electrical loads. Developed mechanical and electric strip Zones are arrested by prescribing over their rims uniform, normal, cohesive yield point stress and Saturation limit electric displacement. Two cases are considered when Saturation Zone is bigger than developed yield Zone and vice versa. Stroh formulation together with complex variable technique is employed to obtain the solution. Closed form expressions are derived for Saturation Zone length, yield Zone length, crack opening displacement (COD), crack opening potential jump (COP) and energy release rate (ERR). An illustrative numerical study is prescribed to determine the effect of various parameters on the crack growth arrest and presented graphically. The results reveal that the model is capable of crack arrest under small-scale mechanical and electric yielding.
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Strip-electromechanical model solution for piezoelectric plate cut along two semi-permeable collinear cracks
Archive of Applied Mechanics, 2013Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:A strip electric Saturation and mechanical yielding model solution is proposed for a piezoelectric plate cut along two equal collinear semi-permeable mode-I cracks with electrical polarization reaching a Saturation limit and normal stress reaching a yield stress along a line segment in front of the cracks. By using Stroh formalism and complex variable technique, we derived the analytical solution for the field quantities. Three different situations are investigated when developed electrical Saturation Zone is bigger/smaller or equal to the developed mechanical yield Zone. Numerical results show that the effect of different electric boundary conditions on the crack opening displacement and crack opening potential drop is significant and should not be ignored. The influence of electric load displacement on the energy release rate is also investigated for PZT-4, PZT-5H and BaTiO_3 ceramics, and it may assists for the correct choosing of ceramic for specific job.
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A study on influence of poling direction on piezoelectric plate weakened by two collinear semi-permeable cracks
Acta Mechanica, 2013Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:A study on the influence of change in poling direction is carried out for mechanical and electric strip-yield model for a transversely isotropic piezoelectric plate cut along two equal collinear semi-permeable straight hairline cracks. Two cases are considered, when the developed Saturation Zone is bigger or smaller than mechanical yield Zone. The Stroh formalism and complex variable technique are employed to obtain the solution. The effect of change in poling direction is studied on crack opening displacement, crack opening potential drop and energy release rate. Also, a study is carried out on the suitability of crack closure for different piezoelectric ceramics. The obtained results are presented graphically and discussed.
R. R. Bhargava - One of the best experts on this subject based on the ideXlab platform.
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Complex variable approach in studying modified polarization Saturation model in two-dimensional semipermeable piezoelectric media
Applied Mathematics and Mechanics, 2017Co-Authors: S. Singh, K. Sharma, R. R. BhargavaAbstract:A modified polarization Saturation model is proposed and addressed math-ematically using a complex variable approach in two-dimensional (2D) semipermeable piezoelectric media. In this model, an existing polarization Saturation (PS) model in 2D piezoelectric media is modified by considering a linearly varying saturated normal electric displacement load in place of a constant normal electric displacement load, applied on a saturated electric Zone. A centre cracked infinite 2D piezoelectric domain subject to an arbitrary poling direction and in-plane electromechanical loadings is considered for the analytical and numerical studies. Here, the problem is mathematically modeled as a non-homogeneous Riemann-Hilbert problem in terms of unknown complex potential functions representing electric displacement and stress components. Having solved the Hilbert problem, the solutions to the saturated Zone length, the crack opening displace-ment (COD), the crack opening potential (COP), and the local stress intensity factors (SIFs) are obtained in explicit forms. A numerical study is also presented for the proposed modified model, showing the effects of the Saturation condition on the applied electrical loading, the Saturation Zone length, and the COP. The results of fracture parameters obtained from the proposed model are compared with the existing PS model subject to electrical loading, crack face conditions, and polarization angles.
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Strip-coalesced interior Zone model for two unequal collinear cracks weakening piezoelectric media
Applied Mathematics and Mechanics, 2014Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:In this paper, a mathematical strip-Saturation model is proposed for a poled transversely isotropic piezoelectric plate weakened by two impermeable unequal-collinear hairline straight cracks. Remotely applied in-plane unidirectional electromechanical loads open the cracks in mode-I such that the Saturation Zone developed at the interior tips of cracks gets coalesced. The developed Saturation Zones are arrested by distributing over their rims in-plane normal cohesive electrical displacement. The problem is solved using the Stroh formalism and the complex variable technique. The expressions are derived for the stress intensity factors (SIFs), the lengths of the Saturation Zones developed, the crack opening displacement (COD), and the energy release rate. An illustrative numerical case study is presented for the poled PZT-5H ceramic to investigate the effect of prescribed electromechanical loads on parameters affecting crack arrest. Also, the effect of different lengths of cracks on the SIFs and the local energy release rate (LERR) has been studied. The results obtained are graphically presented and analyzed.
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Strip electro-mechanical yielding model for piezoelectric plate cut along two equal collinear cracks
Applied Mathematical Modelling, 2013Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:Abstract The multiple-crack problems for piezoelectric ceramics till now have not yet address the crack opening arrest problem. The present work addresses this paucity. A 2-D strip-electro-mechanical yielding model is proposed for a transversely isotropic piezoelectric media weakened by two internal equal collinear straight cracks. The infinite boundary is prescribed with combined uniform constant in-plane mechanical and electrical loads. Developed mechanical and electric strip Zones are arrested by prescribing over their rims uniform, normal, cohesive yield point stress and Saturation limit electric displacement. Two cases are considered when Saturation Zone is bigger than developed yield Zone and vice versa. Stroh formulation together with complex variable technique is employed to obtain the solution. Closed form expressions are derived for Saturation Zone length, yield Zone length, crack opening displacement (COD), crack opening potential jump (COP) and energy release rate (ERR). An illustrative numerical study is prescribed to determine the effect of various parameters on the crack growth arrest and presented graphically. The results reveal that the model is capable of crack arrest under small-scale mechanical and electric yielding.
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Strip-electromechanical model solution for piezoelectric plate cut along two semi-permeable collinear cracks
Archive of Applied Mechanics, 2013Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:A strip electric Saturation and mechanical yielding model solution is proposed for a piezoelectric plate cut along two equal collinear semi-permeable mode-I cracks with electrical polarization reaching a Saturation limit and normal stress reaching a yield stress along a line segment in front of the cracks. By using Stroh formalism and complex variable technique, we derived the analytical solution for the field quantities. Three different situations are investigated when developed electrical Saturation Zone is bigger/smaller or equal to the developed mechanical yield Zone. Numerical results show that the effect of different electric boundary conditions on the crack opening displacement and crack opening potential drop is significant and should not be ignored. The influence of electric load displacement on the energy release rate is also investigated for PZT-4, PZT-5H and BaTiO_3 ceramics, and it may assists for the correct choosing of ceramic for specific job.
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A study on influence of poling direction on piezoelectric plate weakened by two collinear semi-permeable cracks
Acta Mechanica, 2013Co-Authors: R. R. Bhargava, Kamlesh JangidAbstract:A study on the influence of change in poling direction is carried out for mechanical and electric strip-yield model for a transversely isotropic piezoelectric plate cut along two equal collinear semi-permeable straight hairline cracks. Two cases are considered, when the developed Saturation Zone is bigger or smaller than mechanical yield Zone. The Stroh formalism and complex variable technique are employed to obtain the solution. The effect of change in poling direction is studied on crack opening displacement, crack opening potential drop and energy release rate. Also, a study is carried out on the suitability of crack closure for different piezoelectric ceramics. The obtained results are presented graphically and discussed.
Huang Jiadong - One of the best experts on this subject based on the ideXlab platform.
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identification of transformer magnetizing inrush based on waveform characteristics of equivalent instantaneous inductance in non Saturation Zone
Southern Power System Technology, 2010Co-Authors: Huang JiadongAbstract:A new waveform fluctuation function algorithm to distinguish the inrush and fault current of power transformer is put forward based on the waveform differences of equivalent instantaneous inductance.The algorithm can identify inrush and fault current by calculating the waveform coefficient according to the characteristics of equivalent instantaneous inductance rapidly changing in non-Saturation Zone.The experimental results indicate that the proposed method is reliable and sensitive even to low level of turn-turn faults.In addition,the method just need to measure the three-phase difference currents and primary voltages without adopting any parameters of the transformer,and thus with little calculation,simple and easy to set up.
H. G. Beom - One of the best experts on this subject based on the ideXlab platform.
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Asymptotic analysis of an impermeable crack in an electrostrictive material subjected to electric loading
International Journal of Solids and Structures, 2020Co-Authors: H. G. BeomAbstract:AbstractThe simple asymptotic problem of an impermeable crack in an electrostrictive ceramic under electric loading is analyzed. Closed form solutions of elastic fields are obtained by using the complex function theory. It is found that the KI-dominant region is very small compared to the electric Saturation Zone. A fracture parameter for an electrostrictive material subjected to electric loading is discussed. In order to investigate the influence of the transverse electric displacement on fracture behavior under the small-scale conditions, we also consider the modified boundary layer problem of a crack in an electrostrictive material. Analytic solutions of electric displacement fields for the asymptotic problem are obtained based on the nonlinear dielectric theory from a modified boundary layer analysis. The shape of the electric displacement Saturation Zone is shown to depend on the transverse electric displacement. Stress intensity factors induced by the electrostrictive strains are evaluated using the nonlinear solution of the electric displacements. It is found that the transverse electric displacement affects strongly the variation of the mode mixity
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Modified boundary layer analysis of an electrode in an electrostrictive material
Archive of Applied Mechanics, 2008Co-Authors: H. G. BeomAbstract:A thin electrode embedded in an electrostrictive material under electric loading is investigated. In order to obtain an asymptotic form of electric fields and elastic fields near the electrode edge, we consider a modified boundary layer problem of an electrode in an electrostrictive material under the small scale Saturation condition. The exact electric solution for the electrode is obtained by using the complex function theory. It is found that the shape of the electric displacement Saturation Zone is sensitive to the transverse electric displacement. A perturbation solution of stress fields induced by incompatible electrostrictive strains for the small value of the transverse electric displacement is obtained. The influence of transverse electric displacement on a microcrack initiation from the electrode edge is also discussed.
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A Crack with an Electric Displacement Saturation Zone in an Electrostrictive Material
Archive of Applied Mechanics, 2006Co-Authors: H. G. BeomAbstract:A crack with an electric displacement Saturation Zone in an electrostrictive material under purely electric loading is analyzed. A strip Saturation model is here employed to investigate the effect of the electrical polarization Saturation on electric fields and elastic fields. A closed form solution of electric fields and elastic fields for the crack with the strip Saturation Zone is obtained by using the complex function theory. It is found that the K _ I -dominant region is very small compared to the strip Saturation Zone. The generalized Dugdale Zone model is also employed in order to investigate the effect of the Saturation Zone shape on the stress intensity factor. Using the body force analogy, the stress intensity factor for the asymptotic problem of a crack with an elliptical Saturation Zone is evaluated numerically.
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Effect of electric displacement Saturation on the stress intensity factor for a crack in a ferroelectric ceramic
Mechanics Research Communications, 2004Co-Authors: K.m. Jeong, H. G. BeomAbstract:Abstract A crack in a ferroelectric ceramic with perfect Saturation under electric loading is analyzed. The boundary of the electric displacement Saturation Zone ahead of the crack tip is assumed to be ellipse in shape. The shape and size of ferroelectric domain switching Zone near a crack tip is determined based on the nonlinear electric theory. The stress intensity factor induced by ferroelectric domain switching under small-scale conditions is numerically obtained as a function of the electric Saturation Zone parameter and the ratio of the coercive electric field to the yield electric field. It is found that the stress intensity factor increases as the ratio of the semi-axes of the Saturation ellipse increases.
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Effect of polarization Saturation on the stress intensity factor for a crack in an electrostrictive ceramic
Philosophical Magazine, 2001Co-Authors: H. G. BeomAbstract:A crack with electrically impermeable surfaces in an electrostrictive ceramic with perfect Saturation under electric loading is analysed. A strip Saturation model is introduced to investigate the effect of the electrical polarization Saturation on the stress intensity factor. The solutions of electric and elastic fields for the insulating crack with a strip Saturation Zone under large-scale Saturation conditions are derived using the complex function theory. The stress intensity factor is obtained on the basis of the strip Saturation model and is compared with that obtained on the basis of the small-scale Saturation model. It is found that the two models predict nearly indistinguishable stress intensity factors.
W. J. Wang - One of the best experts on this subject based on the ideXlab platform.
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Correlation Analysis of Waveforms in Non-Saturation Zone Based Method to Identify the Magnetizing Inrush in Transformer
2006 International Conference on Power System Technology, 2006Co-Authors: D. Q. Bi, X. A. Zhang, H. H. Yang, G. W. Yu, X. H. Wang, W. J. WangAbstract:A novel algorithm base on the correlation analysis of waveforms to distinguish between the magnetizing inrush and the short-circuit fault current is proposed. The algorithm makes use of the characteristics of differential current waveform in the non-Saturation Zone that it is similar with a part of sinusoidal wave under the short-circuit fault and far different with the sinusoid under the inrush condition. To realize this algorithm, the non-Saturation Zone of transformer is decided by comparing the algebraic sum of sampling data in a short slide window of differential current under the magnetizing inrush or the short-circuit fault, then two kinds of normal sinusoidal waveform are structured according to the value and position of peak point of differential current in the non-Saturation Zone. The correlation coefficients between the original waveform and two structured sinusoidal waveforms are calculated, and the magnetizing inrush or fault current is judged according to the average of two correlation coefficients. The experimental results verify that the algorithm can correctly open the differential protection in short time for the internal short-circuit fault in operation and energizing with a turn-to-turn short-circuit fault, reliably block the protection during the magnetizing inrush, and obtains good immunity to the Saturation of current transformer. Low computation and requirement contribute to this algorithm is performed in practice.
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A ratio variation of equivalent instantaneous inductance based method to identify magnetizing inrush in transformers
2005 International Conference on Electrical Machines and Systems, 2005Co-Authors: D. Q. Bi, X. H. Wang, W.x. Liang, W. J. WangAbstract:In terms of the characteristic of instantaneous magnetizing inductance reflecting the Saturation stage in transformer, an improved method is proposed to distinguish between the magnetizing inrush current and short-circuit fault based on the ratio of average equivalent instantaneous inductances between the non-Saturation and the Saturation Zone, which are divided according to a threshold of differential current. During the inrush, the value of equivalent instantaneous inductance varies severely from small to large as the transformer entering into the Saturation and withdrawing from it, so the ratio of average equivalent instantaneous inductances between the non-Saturation and the Saturation Zone is very large in one cycle. However, for the short-circuit fault in transformer, the equivalent instantaneous inductance is very small, and keeps little variation, so the ratio is approximately equal to one. The principle and setting of this method is simple and easy, and its identification time is short. The experimental results verify that the method is correct and effective
