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Finite-element inverse analysis of residual stress for laser welding based on a contour method
摘要： The thermal effect of laser welding degrades the local material properties, and this inevitably leads to thermal deformation and thermal residual stress in welded joints. In this study, the residual stress distribution of laser-welded Al–Li alloy parts was measured by a combination of the contour method and finite-element simulation. First, the contour deformation of the cutting surfaces of welded parts resulting from the release of residual stress was measured by a coordinator. Then, the reverse contour deformation was applied to the finite-element model as the displacement boundary condition to invert the full-field residual stress of the cutting surface. Furthermore, a thermal/structural sequential coupling analysis method was used to establish a complete three-dimensional finite-element model of a laser-welded plate and calculate the residual stress field, taking the actual weld morphology as the characteristic parameter of the heat source, using the improved conical heat source model of laser welding. The result is consistent with the results of the contour method.
关键词： Laser welding,Residual stress,Contour method,Thermal/structural finite-element analysis,Improved conical heat source model
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Ottawa, ON, Canada (2019.7.8-2019.7.12)] 2019 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Analysis of Carrier Transport through GaN/AlN Periodically Stacked Structure Photodiode
摘要： In this paper, we focus our attention on the performance of read heads under the off-track reading condition when the reader is under the influence of the recorded magnetization patterns on the medium, and analyze how the magnetic field due to various data patterns impacts the read head behavior. The analysis is based on the micromagnetic modeling of the state of magnetization in read sensor considering its external magnetic fields due to both the hard bias and the media magnetization pattern. The effects of various magnetization patterns on media are analyzed. The effect of thermal magnetic agitation of the gyromagnetical precession of magnetizations is also evaluated. It is shown that to account for such effect is important for evaluation of magnetic recording schemes for extremely high density.
关键词： Finite element analysis,micromagnetics,magnetic recording,magnetic sensors
更新于2025-09-23 15:19:57
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Study on the Mechanism of Ultrasonic Power Measurement Sensor based on Pyroelectric Effect
摘要： PVDF pyroelectric sensor has been widely applied in many fields, such as intruder alarm. Nowadays, this sensor shows a potential for ultrasonic power measurement. However, the transformation mechanism between the acoustic and pyroelectric signals has not been particularly studied until now. In this paper, a physical model was introduced for theoretical study of the mechanism of energy transformations. In addition, a simulation program based on finite-element analysis method was built up for analyzing the ultrasound propagation characteristics and the temperature rise on the PVDF, as well it predicted the waveform and amplitude of the generated pyroelectric signal. Besides that, a PVDF pyroelectric sensor was fabricated and used for acoustic power measurement experiment. Finally, the experiment and simulation results were compared, confirming that the physical model is suitable for pyroelectric sensor characteristics analysis. It can also provide useful suggestions for the design and fabrication of PVDF pyroelectric sensors with high sensitivity.
关键词： ultrasonic power,PVDF,finite-element analysis,pyroelectric sensor
更新于2025-09-19 17:15:36
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The Application of Least-Squares Finite Element Method to Simulate Wave Propagation in Bianisotropic Media
摘要： The finite element method (FEM) has been one of the major numerical techniques for electromagnetics (EM) ever since the introduction of the spurious-free edge element. On the other hand, a so-called least-squares finite element method (LSFEM) is becoming increasingly popular due to its unique properties. For instance, the generated stiffness matrix is positive definite. Effort has been made to apply this node-element-based LSFEM to model EM problems, mostly in the theoretical aspect. In this paper, we will use normalized Maxwell’s equations incorporated with the constitutive relations of bianisotropic media, which represents the most general cases in the linear regime. Subsequently, the corresponding variational formulation is derived, followed by the generation of matrix systems. We then implement and validate various boundary conditions. Further we apply this scheme to simulate wave scattering in the presence of bianisotropic media that are categorized into 3 types. A good convergence rate and agreement between the LSFEM results and the referenced solutions has been achieved, which proves the Lagrange-element-based LSFEM as a feasible alternative to the edge-element-based FEM currently used in EM modeling.
关键词： Electromagnetic metamaterials,Electromagnetic propagation,Finite element analysis
更新于2025-09-19 17:15:36
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Liquid Crystal Based Rib Waveguide
摘要： In this paper, we focus our attention on the performance of read heads under the off-track reading condition when the reader is under the influence of the recorded magnetization patterns on the medium, and analyze how the magnetic field due to various data patterns impacts the read head behavior. The analysis is based on the micromagnetic modeling of the state of magnetization in read sensor considering its external magnetic fields due to both the hard bias and the media magnetization pattern. The effects of various magnetization patterns on media are analyzed. The effect of thermal magnetic agitation of the gyromagnetical precession of magnetizations is also evaluated. It is shown that to account for such effect is important for evaluation of magnetic recording schemes for extremely high density.
关键词： magnetic sensors,micromagnetics,magnetic recording,Finite element analysis
更新于2025-09-19 17:13:59
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[IEEE TENCON 2018 - 2018 IEEE Region 10 Conference - Jeju, Korea (South) (2018.10.28-2018.10.31)] TENCON 2018 - 2018 IEEE Region 10 Conference - Examination of Compact and Online Diagnosis Methods Based on Temporal Fluctuation of String Currents of a Photovoltaic Solar Plant
摘要： In this paper, we focus our attention on the performance of read heads under the off-track reading condition when the reader is under the influence of the recorded magnetization patterns on the medium, and analyze how the magnetic field due to various data patterns impacts the read head behavior. The analysis is based on the micromagnetic modeling of the state of magnetization in read sensor considering its external magnetic fields due to both the hard bias and the media magnetization pattern. The effects of various magnetization patterns on media are analyzed. The effect of thermal magnetic agitation of the gyromagnetical precession of magnetizations is also evaluated. It is shown that to account for such effect is important for evaluation of magnetic recording schemes for extremely high density.
关键词： magnetic sensors,micromagnetics,magnetic recording,Finite element analysis
更新于2025-09-19 17:13:59
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DEFORMATION ANALYSIS OF H62 Cu ALLOY FOIL SUBJECTED TO MULTI-PULSED LASER DYNAMIC FORMING: SIMULATIONS
摘要： By utilizing the ABAQUS software, this paper simulates and analyzes the forming of the H62 foil subjected to multi-pulse laser dynamic forming (LDF). The Johnson–Cook failure mode is adopted to predict the fracture threshold value of the H62 foil. Compared with the single-pulsed LDF, the multi-pulsed LDF improves the limit depth and forming quality of the foil e?ectively. With the increase of impact number, the uniformity of foil is e?ectively improved. Appropriate peak pressure and impact number are important to increase limit forming depth and improve forming quality.
关键词： finite element analysis,Laser dynamic forming,H62 Cu alloy foil,limit forming depth,multi impacts
更新于2025-09-19 17:13:59
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Finite Element Modelling and Analysis for Dynamic Investigation of a Laser Spot Welded Hat-Plate Structure under Initial Stress Influence
摘要： This paper presents the finite element modelling and analysis of the dynamic behaviour of a laser spot welded structure under the influence of initial stress. Modal based updating with a new scheme was used to improve the finite element model of the structure. Element connectors with CWELD ELPAT format were used to represent the laser spot welded in the structure. The modal parameters of the structure were measured using impact hammer testing and roving accelerometers under free-free boundary conditions. NASTRAN SOL 200 was used in updating the finite element model in light of the experimental results. In this study, it was found that modal updating with the new scheme has successfully matched the finite element model of the welded structure with the experimental model. The achievement demonstrates the accuracy and efficiency of the proposed new scheme.
关键词： Finite Element Analysis,Initial Stress,Experimental Modal Analysis,Model Updating
更新于2025-09-16 10:30:52
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Increasing of ENF Bonded Joints Performance by Design of Laser Surface Texturing
摘要： The quality of a bonded joint is strongly linked to the surface treatment used for the adherends. Recently, many studies have showed the opportunity to use a CO2 laser for enhancing the mechanical properties of bonded joints in FRP. Nowadays, to optimize their process parameters and texturing represent a necessary step for the growth in this technology. In this work, an experimental and numerical study of the effect of laser texturing on end notched flexure (ENF) joints realized in CFRP has been developed. The laser texturing showed an important effect on the mechanical resistance of ENF joints, with an increase of at least 76% respect untreated ones. The numerical results showed a good agreement with the experimental ones. Therefore, it is possible to design of the laser texturing for optimizing the mechanical response of bonded joints.
关键词： finite element analysis,Adhesive bonding,laser treatment
更新于2025-09-16 10:30:52
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Damage Evaluation of TBC by Rapid Thermal Cycling Test Utilizing a Laser Irradiation
摘要： Thermal barrier coating (TBC) is deposited onto the gas turbine blade surface in order to protect the substrate from high-temperature combustion gas. Cracks and delamination of the ceramic coating which come from high heat flux loading are serious problem in TBC. In this study, the rapid thermal cycling device utilizing laser irradiation was developed. It was then investigated how the damage progresses in the ceramic coating exposed to cyclic rapid thermal loading. As a result, a sintering layer was formed in the surface of the ceramic coating, although such phenomenon was not recognized in TBC sample tested by the conventional thermal cycling test using an electric furnace. It was also revealed from the cross-sectional observation that the vertical crack was initiated at the surface of TBC and propagated into sintering layer. Finally, mechanical factors of those damages from finite element analysis using the TBC model including sintering progress was discussed.
关键词： Thermal Barrier Coatings,Gas Turbine,Finite Element Analysis,Laser irradiation
更新于2025-09-16 10:30:52