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Influence of multiple laser impacts on thin leading edges of turbine blade
摘要： Laser shock peening is a mechanical surface improvement treatment used to enhance the fatigue life of critical components. This paper investigates the influence of multiple square laser impacts to study their special effect on the diverse mechanical behaviours of the thin leading edge surface of turbine blades. Most works existing in the literature have presented experimental investigations. The originality of our paper is to validate and numerically simulate the proposed model. Indeed, a 3D finite element method of a thin leading edge specimen, Ti–6Al–4V, of a turbine blade is numerically simulated using the ABAQUS software. The mechanical surface modifications (residual stresses, equivalent plastic strains and Johnson–Cook superficial damage) induced by the multiple square laser impact are examined in detail. The main purpose of this investigation is to determine the effects of single-sided and double-sided laser shock peening.
关键词： turbine blade,thin leading edge,Ti–6Al–4V,multiple square laser impacts,finite element method,equivalent plastic strain,Laser shock peening,Johnson–Cook superficial damage,compressive residual stress
更新于2025-09-12 10:27:22
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Residual stress and welding distortion of Al/steel butt joint by arc-assisted laser welding-brazing
摘要： The thermo-elastic?plastic finite element method (FEM) is used to simulate the thermo-mechanical behavior of Al/steel tungsten inert gas (TIG) arc-assisted laser welding-brazing (A-LWB) butt joint. The influence of material nonlinearity, geometrical nonlinearity and work hardening on the welding process is studied, and the differences in the welding temperature field, residual stress and welding distortion by A-LWB and by single laser welding-brazing (SLWB) are analyzed. The results show that the thermal cycle, residual stress distribution and welding distortion by the numerical simulation are in good agreement with the measured data by experiments, which verifies the effectiveness of FEM. Compared with the SLWB, A-LWB can make the high-temperature distribution zone of weld in width direction wider, decrease the transverse tensile stress in the weld and reduce the distribution range of longitudinal tensile stress. And the welding deformation also decreases to some extent.
关键词： arc-assisted laser welding-brazing (A-LWB),residual stress,welding distortion,Al/steel,temperature field,finite element method (FEM)
更新于2025-09-12 10:27:22
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Optimized arrangement of vertical cavity surface emitting laser arrays to improve thermal characteristics
摘要： An optimization method for an arrangement of vertical cavity surface emitting laser (VCSEL) arrays to improve thermal characteristics of the arrays is presented. The method is based on the principle of minimum potential energy and is implemented by a self-organizing algorithm. The thermal and electrical properties of the active regions of the unoptimized and optimized arrays were obtained by a self-consistent thermoelectric simulation of the VCSEL structure based on the finite element method. The output characteristics of the unoptimized and optimized 4 × 4 square VCSEL arrays were studied theoretically and practically. The results showed that the optimized arrays have improved thermal characteristics.
关键词： VCSEL arrays,optimization method,thermal characteristics,self-organizing algorithm,finite element method
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Fabrication of Ultrasmall Silicon Waveguide Lenses Designed by Wavefront-Matching Method
摘要： We design and fabricate ultrasmall silicon waveguide lenses designed by a wavefront-matching (WFM) method by a standard CMOS process. It is experimentally demonstrated that a low-loss several micron free-space light propagation is possible by using the waveguide lens designed by the WFM method.
关键词： Finite-element method,Optimum design method,Silicon waveguide device
更新于2025-09-11 14:15:04
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Fano Resonance in a MIM Waveguide with Two Triangle Stubs Coupled with a Split-Ring Nanocavity for Sensing Application
摘要： Herein, a compact refractive index nanosensor comprising a metal-insulator-metal (MIM) waveguide with symmetric two triangle stubs coupled with a circular split-ring resonance cavity (CSRRC) is theoretically presented. An analysis of the propagation characteristics of the designed structure is discussed employing the finite element method (FEM). The calculation results revealed that a Fano resonance outline emerged, which results from an interaction between the continuous broadband state of the waveguide with two symmetric triangle stubs and the discrete narrowband state of the CSRRC. The influence of geometric parameters on sensing properties was studied in detail. The maximum sensitivity reached 1500 nm/RIU with a high figure of merit of 65.2. The presented structure has great applications for on-chip plasmonic nanosensors.
关键词： refractive index sensor,metal-insulator-metal waveguide,Fano resonance,finite element method
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 2nd International Conference on Electronic Information and Communication Technology (ICEICT) - Harbin, China (2019.1.20-2019.1.22)] 2019 IEEE 2nd International Conference on Electronic Information and Communication Technology (ICEICT) - Method of waveguide port excitation producing appointed direction wave in FEM calculation
摘要： The calculational formulations of exciting appointed direction wave for finite element method are presented. Based on two dimensional finite element method, modes fields of electrical field and magnetic field are achieved firstly. Equivalent source of electric and magnetic current sources are presented simultaneously, which ensure the sole direction of wave that one wants. The calculating results validate the correctness of formulation and method.
关键词： waveguide ports excitation,electric and mangnetic current sources,finite element method
更新于2025-09-11 14:15:04
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Real-time observation of crack propagation and stress analysis during laser cutting of glass
摘要： Laser cutting of glass using a continuous-wave laser is attracting considerable attention because of its high processing speed and minimized generation of microcracks. During laser cutting of glass, a crack develops because of thermal stress and divides the glass plate. In this study, we observed crack propagation during laser cutting of glass in real time and found the distance between the crack tip and the laser irradiation position was 150 μm. Furthermore, we investigated the in?uence of the distance between the crack tip and the laser irradiation position on stress distribution and the stress condition necessary for crack growth. The results show the maximum principal stress at the crack tip increased as the distance between the crack tip and the laser irradiation position increased. In addition, we found that the crack developed when the maximum tensile stress of the crack tip reached 99 MPa. These results can be expected to enable the control of crack propagation and the estimation of appropriate processing conditions during laser cutting of glass.
关键词： laser,glass,cutting,finite element method,crack
更新于2025-09-11 14:15:04
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Parallel Simulation of Fully Coupled Electrothermal Processes in Large-Scale Phase-Change Memory Arrays
摘要： Numerical simulation of fully coupled electrothermal processes in phase-change memory (PCM) arrays is performed in this article. For realizing the ability in simulating the electrothermal responses of large-scale PCM arrays, an in-house parallel simulator based on domain decomposition method (DDM) and time-domain finite element method (FETD) is developed, with its performance evaluated in terms of accuracy and scalability. Then, thermal crosstalk in the PCM array is investigated using the developed simulator, and a diamond layer is introduced to suppress thermal crosstalk. Furthermore, the scaling effects of PCM arrays on their electrothermal performance are examined. A scheme for multibit PCM design is proposed, and the electrothermal characteristics of proposed 2-bit PCM cells and arrays are studied numerically.
关键词： phase-change memory (PCM),multibit PCM,parallel computing,time-domain finite element method (FETD),Electrothermal simulation,thermal crosstalk
更新于2025-09-11 14:15:04
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Efficient thermal finite element modeling of selective laser melting of Inconel 718
摘要： In the powder bed fusion process, an accurate prediction of the transient temperature field of a part is essential to calculate the subsequent thermal stress evolution and microstructure propagation in that part. The experimental method is time-consuming and expensive since the temperature field is controlled by many process parameters. Numerical heat transfer models can be used to estimate the temperature field at any time point. However, traditional numerical simulation schemes are not suitable for the layer-wised fabrication process due to the extremely high computational cost. The computational cost mainly relies on the element number and time step size. This research provides a new efficient and part-level simulation scheme based on an open-source finite element library, which is able to adaptively refine and coarsen the mesh and solve finite element equations with multiple processors in a parallel way. Here, a new mesh strategy that aims to reduce the element number while keeping the solution accuracy is developed. The simulation speed is 12× to 18× faster compared with the traditional simulation scheme depending on the scale of the simulated domain and number of processors. Simulation results have been compared with the experimental results of an Inconel 718 component. It is shown that the testing point in the simulation experiences the same thermal cycles of the same point in the experiment. This simulation scheme can also be used to optimize the process parameters such as scanning pattern, scan velocity, and layer thickness and can be easily extended to other additive manufacturing processes.
关键词： Selective laser melting,Finite element method,MPI,Heat transfer,Adaptive mesh
更新于2025-09-11 14:15:04
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Label-free detection of ambient refractive index based on plasmonic Bragg gratings embedded resonator cavity sensor
摘要： In this work, we incorporated Bragg gratings in the standard ring resonator design in order to enhance the sensitivity of the refractive index sensor. The transmission spectrum and electric field distribution of the device are simulated using the finite element method (FEM). The numerical simulation results obtained from the transmission spectrum are used to examine the sensing characteristics of the structure. The size of the grating teeth has a significant effect on the intensification of surface plasmons which in turns enhances the interaction between the ambient medium and the light. Bragg grating embedded resonator cavity design has the best sensitivity, FOM and Q-factor of 1680 nm/RIU, 48 and 48.4, respectively which is much higher than several previously reported values.
关键词： metal-insulator-metal waveguide,Plasmonics,Bragg grating,Refractive index sensor,finite element method
更新于2025-09-11 14:15:04