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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Finite-Element Analysis of Three-Dimensional Polarization Mapping with Pulsed Diode Lasers
摘要： Measuring the distribution of electrical polarization and space charge with focused thermal pulses or waves is one of the basic characterization techniques in electret research. However, in multi-layer systems, reconstructing the polarization from the measured transient current requires a multi-physics approach using finite element analysis. This method is feasible for investigating a range of geometries, including samples with buried light-absorbing electrodes. The present work shows the modeling of the transient thermal-pulse current for a metal-polymer-metal sample, heated on one side with a 15 μs Gaussian-shaped laser beam.
关键词： Pyroelectricity,Finite Element Analysis,Laser Intensity Modulation Method,Thermal Pulse Tomography,Dielectrics
更新于2025-09-11 14:15:04
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Thermo-Mechanical Analysis of Laser Additive Manufacturing for Metals
摘要： The aim of this study is to develop a finite element analysis technique to characterize the distributions of temperature and stress in the process of multilayer deposition of metallic powders by laser additive manufacturing (LAM). Simulation results indicate the residual normal stress in the laser moving direction is greater than that in other directions due to a larger temperature gradient, and it increases with number of deposited layers. Highly residual stresses are present in the LAM build and at the base nearby the interface between the build and base.
关键词： laser additive manufacturing,temperature gradient,finite element analysis,metal,residual stress
更新于2025-09-11 14:15:04
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Efficient and quantitative analysis of photon density of states for two-dimensional photonic crystals with omnidirectional light propagation
摘要： Omnidirectional light propagation in two-dimensional (2D) photonic crystals (PCs) has been investigated by extending the formerly developed 2D finite element analysis (FEA) of in-plane light propagation in which the corresponding band structure (BS) and photon density of states (PDOS) of 2D PCs with complex geometry configurations had been calculated more accurately by using an adaptive FEA in real space for both the transverse electric (TE) and transverse magnetic (TM) modes. In this work, by adopting a wave-guiding theory under the consideration of translational symmetry, the omnidirectional PDOS corresponding to both the radiative and evanescent waves can be calculated efficiently based on the in-plane dispersion relations of both TE and TM modes within the irreducible Brillouin zone. We demonstrate that the complete band gaps shown by previous work considering only the radiative modes will be closed by including the contributions of the evanescent modes. These results are of general importance and relevance to the spontaneous emission by an atom or to dipole radiation in 2D periodic structures. In addition, it may serve as an efficient approach to identifying the existence of a complete photonic band gap in a 2D PC instead of using time-consuming three-dimensional BS calculations.
关键词： two-dimensional photonic crystals,radiative and evanescent waves,finite element analysis,photon density of states,omnidirectional light propagation
更新于2025-09-10 09:29:36
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Piezoelastic response of smart functionally graded structure with integrated piezoelectric layers using discrete double directors shell element
摘要： The purpose of the paper is to predict the electromechanical behavior of composite shell structures with embedded piezoelectric layers using 3D-shell model based on a discrete double directors shell element. The implementation is applicable to the analysis of isotropic and functionally graded shells with integrated piezoelectric layers. The third-order shear deformation theory is introduced in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The present results were compared with reference solutions from literature in order to verify the accuracy of the present formulation and excellent agreement was found. A parametric study is carried out to highlight the in?uence of material composition and curvature radius on the de?ection and axial stress along the thickness.
关键词： Active functionally graded shells,Finite element analysis,Double director shell,Piezoelectric sensors/actuators,Smart structures
更新于2025-09-10 09:29:36
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Improvement of electromechanical coupling coefficient in shear-mode of piezoelectric ceramics
摘要： Shear vibration mode of piezoelectric ceramic has been widely used in energy harvesting for its high electromechanical coupling coefficient (k15) and high piezoelectric constant (d15). In this study, the effects of dimensions on the piezoelectric shear performance of PZT-5A type ceramic were initially studied with ATILA/GiD finite element simulation to improve k15, and verified by experiments. We found out k15 dominantly correlates with the ratio of width to thickness, and dimension optimization was conducted for the first and high order shear vibrations. As a result, a maximum electromechanical coupling coefficient for k15 shear-mode reaching 0.612 was obtained in the first order harmonics. It is worth to note that the dimension ratio for optimized electromechanical coupling factor were in a similar scale regardless of the order of harmonics. In addition to the dimension optimization, the effect of mode coupling between shear vibration mode and unwanted mode was also investigated. The coupling between two vibrations did not only affect electromechanical coupling coefficient but also distorted resonance peak spectrum. Thus, the dimension ratios to avoid mode coupling was provided as the length should far away from the thickness. Finally, the effects of dimensions on mechanical quality factor were examined and the results were discussed. The mechanical quality factor will decrease when the mode coupling happens.
关键词： Electromechanical coupling coefficient,k15 shear-mode,Finite element analysis,Piezoelectric ceramics
更新于2025-09-10 09:29:36
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Magnetic coupling to the advanced Virgo payloads and its impact on the low frequency sensitivity
摘要： We study the electromagnetic coupling of the Advanced Virgo (AdV) input mirror payload in response to a slowly time-varying magnetic field. As the problem is not amenable to analytical solution, we employ and validate a finite element (FE) analysis approach. The FE model is built to represent as faithfully as possible the real object, and it has been validated by comparison with experimental measurements. The intent is to estimate the induced currents and the magnetic field in the neighbourhood of the payload. The procedure found 21 equivalent electrical configurations that are compatible with the measurements. These have been used to compute the magnetic noise contribution to the total AdV strain noise. At the current stage of development, AdV seems to be unaffected by magnetic noise, but we foresee a non-negligible coupling once AdV reaches the design sensitivity.
关键词： finite element analysis,low frequency sensitivity,gravitational-wave detectors,magnetic coupling,Advanced Virgo
更新于2025-09-04 15:30:14