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Study of correlation between edge roughness and gas flow characteristics in laser beam fusion cutting
摘要： Fiber laser fusion cutting trials on AISI 304 stainless steel sheets of 10 mm thickness were performed with the aim to gain further insights into the striation formation process on cut edges. The study is based on a factorial Design-of-Experiment (DoE) approach with consideration of laser power, focal plane position, gas pressure, nozzle stand-off and nozzle diameter as control factors. Analyzed responses include the achievable cutting speed, the cut kerf geometry and the cut edge roughness. In addition, numerical simulations of the cutting gas flow were carried out for adapted kerf geometries and gas parameters. The evaluation of these results reveals strong correlations between experimental roughness values and the numerically computed rear-directed shear stress component within the transition zone between cutting front and cut edge surface. This finding supports the hypothesis that the particular characteristics of the boundary layer zone of the cutting gas flow affects the structure and roughness of cut edges.
关键词： Laser beam fusion cutting,edge roughness,modelling and simulation,gas flow characteristics,design-of-experiments
更新于2025-09-12 10:27:22
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An energy model of machine tools for selective laser melting
摘要： Selective laser melting (SLM) is a metallic additive manufacturing process and uses a laser beam to fuse powder particle, creating 3D-parts. To enable the prediction of energy consumption of SLM, some experimental studies are carried out and can be used for development of empirical models. However, empirical models do not explain the detailed mechanisms of energy consumption of a SLM-machine tool and can be inaccurate when the system component is changed. Therefore, this paper first proposes an approach to develop and apply an energy model for SLM-machine tools based on physical modeling, looking inside of machine functions and describing energetic behavior of system components. Second, a case study with the implementation of the developed energy model is carried out as well.
关键词： energy simulation,SLM-machine tool,energy model,Additive manufacturing,selective laser melting
更新于2025-09-12 10:27:22
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Development of a simulation tool for predicting energy consumption of selective laser melting by using MATLAB/Simulink
摘要： Additive manufacturing (AM) is the umbrella term for manufacturing processes that apply materials layer by layer to create 3D-parts. This technology implies many revolutionary benefits. Selective laser melting (SLM) is one promising metal AM technology which uses a laser beam to melt material on the selective area of a powder bed for creating parts. In order to ensure the sustainable value of SLM, the energy consumption for manufacturing parts with SLM should be analyzed in the design phase. Addressing this issue, this paper introduces the development of a simulation tool for energy consumption prediction with SLM by using MATLAB?/Simulink?. The development approach includes 5 phases: data acquisition, definition of system parameters, modeling using bond graphs, creation of Simulink? models, and creation of data structure and GUI. The result of this work shows that the simulation tool is a useful tool for analyzing and evaluating the energy consumption of SLM in the design phase.
关键词： additive manufacturing,MATLAB/Simulink,energy simulation,selective laser melting
更新于2025-09-12 10:27:22
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Simulation of laser ablation mechanism of silicon nitride by ultrashort pulse laser
摘要： A mathematical model is developed to find the depth of laser ablation and laser-material interaction in laser processing of Si3N4 (SL200-BG) by an ultrashort (picosecond) pulse laser. The model is verified with experiments which were carried out at different laser scan speeds from 1 mm/s to 100 mm/s. Experimental validation shows a model accuracy of 85%. Additionally, the results show that in laser intensities (IL) higher than 1.5 × 109 W/cm2, the laser-material interaction is “Multi Photon Ionization” (MPI) with no effects of thermal reaction while in lower values of IL, there are effects of thermal damages adjacent to the laser cut.
关键词： Ultrashort pulse laser,Simulation,Silicon nitride
更新于2025-09-12 10:27:22
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A Novel Way for Improving the Overall Photoelectric Conversion Efficiency of Dye Sensitized TiO 2 Solar Cells
摘要： The past several years has witnessed a sharp increase in the number of scientists and researchers who have attached great importance to studying Dye sensitized solar cells (DSSCs) because of its low cost and potential high photoelectric conversion efficiency. There are two main factors that influence the photoelectric conversion efficiency of dye sensitized solar cells. One is the low photon absorption rate of solar cells, and other one is the low transmission rate of the photo-generated electrons through the thick nanocrystalline film. So in order to further research and improve efficiency, an accurate model using COMSOL Multiphysics is investigated to reveal the photoresponse and current transport processes of DSSC. Specifically, an optical model is studied to determine how much the solar energy each cell takes in, and an electrical model is investigated to determine how much the overall efficiency. Besides, three adjusted micro/nanostructures of DSSCs have been built for improving the efficiency. The study shows that a more suitable structure can collect more solar energy and improve the electronic diffusion efficiency so as to improve the overall photoelectric conversion efficiency of DSSC.
关键词： Dye sensitized solar cells (DSSCs),COMSOL Multiphysics,Photoelectric coupling simulation,Micro/nanostructure
更新于2025-09-12 10:27:22
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Influence of process parameters on thermal cycle and intermetallic compounds formation in high speed laser weld-brazing of aluminium-steel angle joints
摘要： AA6016-T4 aluminium and DX56D+Z140M steel sheets were joined by fluxless laser weld-brazing process with ER4043 AlSi5 filler wire at high brazing speed. The configuration studied corresponds to typical automotive roof/body-side angle joints. At the interface, the measurements of thermal cycle are performed with K-thermocouples. The results are compared to simulated thermal cycles obtained through SYSWELD Software. Thermal cycles are evaluated with the maximal temperature reached, the time of interaction at high temperature and the cooling speed. Several combinations of laser power and brazing speed are both investigated experimentally and by simulation to study their influence on the thermal cycle and the intermetallic layer thickness. Thermal cycles are discretized to calculate the theoretical growth of the intermetallic compounds with a diffusion-based model. The result is compared to experimental intermetallic layer measured with optical microscopy. The power tends to influence both the maximal temperature and the cooling speed whereas the brazing speed only influences the maximal temperature. The calculation demonstrates the capability to distinguish the process configuration which will lead to the thickest intermetallic layer.
关键词： fluxless laser weld-brazing,simulation,Fe-al dissimilar joints,intermetallic layer calculation,thermal cycle,process parameters
更新于2025-09-12 10:27:22
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Novel thermodynamic efficiency indices for choosing an optimal location for large-scale photovoltaic power generation
摘要： Sustainable energy is a current key priority across the globe. Hence, renewable energy sources have been widely accepted as potential substitutes for fossil fuels in the existing energy infrastructures. A recent report showed that photovoltaic power generation constituted around 100 GW out of 2378 GW of the global renewable power capacity installed in 2018. Consequently, various researchers are investigating how the increasing utilisation of photovoltaics can be handled in order to reduce future environmental impacts; whilst leveraging their operational zero-emission. From a circular economic paradigm, recycling, reuse and reduction strategies are often adopted to improve the sustainability of systems. This study proposes novel thermodynamic ef?ciency indices as a resources reduction strategy. By selecting an optimal location for large-scale photovoltaic power generation (LSPPG), the same amount of resources (such as land space, materials, energy) will achieve higher utilisation ef?ciency. In this study, actual two-year solar radiation and temperature data were sourced from Nigerian Meteorological Agency, Abuja. A probability distribution modeling was used to generate statistical mean values for solar radiation and temperature based on the classical almost sure central limit theory. Then, Photovoltaic modeling and simulation code was used to simulate the power generation characteristics of the LSPPG. Comparative analyses of the results for a 5 MW (MW) LSPPG showed that statistical mean value of power generation, energy ef?ciency index and exergy ef?ciency index range from 0.76 to 0.99 MW, 1.315 to1.254 and 1.298 to1.237, respectively, across the locations studied. Overall, the thermodynamic ef?ciency indices can complement the current laboratory-based rating of the photovoltaic modules in order to establish the environmental, economic and policy rationales for sitting a LSPPG. This would ultimately improve the cradle-to-cradle management of LSPPG installations based on resources reduction strategy.
关键词： Solar energy,Thermodynamic ef?ciency indices,Nigeria,Photovoltaic modules,Modeling and simulation
更新于2025-09-12 10:27:22
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Insights in the effects of quantum dots size and temperature on efficiency of InAs/GaAs quantum dots intermediate band solar cell
摘要： The main problem of the photovoltaic conversion device is that low energy photons cannot excite charge carrier to the conduction band, so that the concept of the quantum dot solar cell is proposed in the intrinsic region of the p-i-n structure. In this work, numerical simulation has been proposed using the Matlab software. We simulate and measure the effects of quantum dots size and temperature on efficiency of GaAs p-i-n structure solar cells incorporating quantum dots (QDs) InAs under illumination. The results show that the efficiency of p-i-n solar cell depend strongly on size of QDs and temperature.
关键词： p-i-n solar cell,simulation,optimization,temperature,quantum dots size
更新于2025-09-12 10:27:22
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COMSOL Simulation of Heat Distribution in Perovskite Solar Cells: Coupled Optical–Electrical–Thermal 3-D Analysis
摘要： The heat dissipation has been rarely investigated in solar cells although it has a significant impact on their performance and reliability. For the first time, an extended three-dimensional (3-D) simulation of heat distribution in perovskite solar cells is presented here. We use COMSOL Multiphysics to investigate the temperature distribution in conventional perovskite solar cells through a coupled optical–electrical–thermal modules. Wave optics module, semiconductor module, and heat transfer in solid module are coupled in COMSOL Multiphysics package to perform the simulation in 3-D wizard. The electrical behavior, optical absorption, and heat conduction or convection are considered to gain insight into heat dissipation across the cell. The simulation results suggest that the heat produced in the cell is best dissipated from the metallic contact where the PbI2 defect forms because of oxidation or decomposition of the perovskite layer at moisture exposure. The generated heat varies significantly from the front FTO contact to bottom metallic electrode. The more heat dissipation and accumulation is observed at the junction and electrode sides too. In our simulations, we consider the Joule heating, nonradiative recombination heating, and heat flux in every layer of the cell and calculate the carrier’s concentration, electric field distribution, Joule heating, Shockley–Read–Hall heating, total heat flux, and temperature distribution across the solar cell structure. The simulations reveal that the metallic contact must be selected as a highly heat conductive material in order to accelerate the heat dissipation on the bottom of the cell and to enhance the cell reliability against temperature increase under normal operation.
关键词： solar cell,heat,perovskite,temperature profile,simulation,COMSOL,distribution
更新于2025-09-12 10:27:22
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Simulation of the GaAsN-based Schottky solar cell prototype
摘要： Dilute nitride semiconductors, such as GaAs1-xNx alloys, have attracted considerable attention due to their unique physical properties and wide range of their possible application in optoelectronics. In this report, a comprehensive numerical simulation under solar illumination of AM1.5G with SCAPS software, is used to find the optimum geometrical and physical parameters that yield the best efficiency of an n-GaAsN based Schottky solar cell. This optimization task is a function of the nitrogen concentration, the metal work function, the doping and the thickness of the GaAsN layer. According to our results, the choice of metal that allows to have a high barrier height while controlling the doping and the thickness of the GaAsN active layer allows the development of high quality GaAs1-xNx based SJSCs. Efficiency greater than 27% is expected with a nitrogen concentration of x = 0.004 for this new design of the n-GaAsN Schottky solar cell.
关键词： solar cell,GaAsN,simulation,Schottky
更新于2025-09-12 10:27:22