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Analysis of Thermal Stress and Temperature Distribution of Laser Power 10.0w and 20.0w on Material Removal in Aluminium Oxide Ceramic
摘要： The momentum look into researches the thermal stress investigation and temperature distribution of laser power 10.0w and 20.0w in aluminum oxide ceramic. Additionally, this paper explores the impact of thermal stress analysis and temperature distribution on material removal prepare. At the point when laser is connected for machining process for making smaller scale groove, temperature distribution assumes an imperative part for that since large amount of heat release by the laser which is influenced the material and deliver a heat affected zone thus material gets melted and vaporize. Thermal Stress is likewise being done because of nearness of thermal impact in material at the time of heat generation and it additionally assumes a decent part to achieve the great material removal handle. Accomplishing a fancied score of particular measurements is conceivable by having control over process parameters of a laser grooving machine which thus represents the measure of material removed. To handle with this, and concentrating on current trend where laser machining is exceptionally Demanded and connected in industry like like bio medical engineering, aerospace, automobile etc., and so on., it is particularly fundamental to concentrate the temperature distribution in the heat affected zone of the material where heat is created (due to heat energy released by laser beam) and equivalent thermal stress in the material body that is in charge of material removal, Achieving a desired groove with great precision. Limited component examination technique utilizing ANSYS is utilized to to simulate and analyze this temperature distribution and equivalent thermal stress of different laser power. In this paper temperature distribution FEM chart with diagrams for 10.0W and 20.0W, Material removal for 10.0W, 20.0W, Equivalent stress FEM diagram with graph for 100W, 200W are appeared furthermore the correlation of laser power in the vicinity of 10.0w and 20.0w are available.
关键词： Temperature Distribution,ANSYS,Laser Power,Material Removal,Thermal Stress
更新于2025-09-12 10:27:22
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Non-dimensional process maps for normalized dilution limits in laser direct metal deposition
摘要： The quality and integrity of laser direct metal deposition (DMD) processes primarily depend on the substrate dilution and the nature of residual stresses in the deposited layer. An adequate amount of melting of the substrate is required to ensure the formation of sound metallurgical bond between the deposited layer and substrate. Insufficient melting and excessive dilution may lead to adverse effects. Furthermore, the dilution also controls the location of the melt front in substrate where maximum tensile residual stresses occur. The presence of tensile residual stresses in the deposited layer may be detrimental to service life, especially, for components repaired using DMD. These challenges can be overcome by predicting and controlling the dilution and the nature of residual stress as a function of process parameters. To model the direct metal deposition process, a 3D coupled metallo-thermomechanical finite element model is employed to predict the temperature and the residual stress due to thermomechanical interactions and metallurgical transformations and the substrate dilution. Non-dimensional process parameters affecting the dilution in laser DMD have been identified using Buckingham-Π theorem. The metallo-thermomechanical model is used to develop empirical relationships via regression to correlate the dimensionless process parameters with the dilution. These correlations are employed in developing the isopleths in the form of process maps, which could predict regions of inadequate fusion and excessive dilution (unduly large substrate melting). It may be noted that the limiting value of dilution corresponds to the condition where the entire deposited layer (cladding) is under compressive residual stresses. Any dilution higher than this will result in excess substrate melting which is undesirable. The limiting values of normalized dilution are estimated to be 1 and ~1.3 corresponding to complete deposit-substrate fusion and presence of entirely compressive residual stress in deposition, respectively. These process maps are designed to provide a theoretical framework for understanding the influence of process parameters and provide informed decisions on the selection of appropriate process parameters for ensuring the quality and integrity of the deposition.
关键词： Laser cladding,residual stress,metallo-thermomechanical finite element model,process maps,dilution,non-dimensional parameters
更新于2025-09-12 10:27:22
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[IEEE 2019 8th International Conference on Modeling Simulation and Applied Optimization (ICMSAO) - Manama, Bahrain (2019.4.15-2019.4.17)] 2019 8th International Conference on Modeling Simulation and Applied Optimization (ICMSAO) - Thermal Analysis in Laser Surface Alloying of Ti6Al4V with TiC
摘要： Laser Surface Alloying employs high laser power density to melt alloying material and a portion of the underlying substrate to form an alloyed layer over substrate. As melting temperature of Ti alloys is very high, it poses difficulty in alloying using conventional methods. Titanium alloys are vulnerable to induced thermal stresses at high temperature. In this study thermal analysis of laser surface alloyed Ti6Al4V with TiC at different laser power and laser spot diameter is modelled. Melt pool depth and developed thermal stresses at different process parameters are predicted. Subsequently, model is verified with published experimental results. It is observed that developed model is adequate in predicting pool depth with 6.43% error. The von-Mises stress is observed to be lower than the yield strength of the material, indicating less possibility of thermally induced cracks.
关键词： Thermal stress,Numerical modelling,Pool depth,Laser surface alloying,Thermal analysis
更新于2025-09-12 10:27:22
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Finite element prediction and validation of residual stress profiles in 316L samples manufactured by laser powder bed fusion
摘要： Laser powder bed fusion (LPBF) processes continue to grow in popularity and much progress has been made in recent years. However, due to the extreme thermal gradients present, significant residual stresses are inevitable and can be detrimental during component service. Critical to mitigating these stresses effectively is the ability to model the thermo-mechanical process accurately and efficiently. A simplified FE modelling methodology has been developed and applied to a cylindrical component built in both the horizontal and vertical orientations. The resulting distortion of the parts following a slitting process was compared with those predicted by the model and good agreement to within 5% was found. The final stress fields in the components were predicted by the model and then examined to assess the principal stresses driving the distortion and the causes of difference in results between the two build orientations.
关键词： LPBF,residual stress,finite element modelling,Laser powder bed fusion,distortion
更新于2025-09-12 10:27:22
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Fatigue Behaviour of Additively Manufactured Inconel 718 Produced by Selective Laser Melting.
摘要： Selective Laser Melted (SLM) Inconel 718 has promising use in various applications, where complex design and excellent strength is required. Yet fatigue properties of respective components in critical load bearing applications are yet poorly understood. Here, we investigate the fatigue behaviour of different notch geometries of as-build specimens at room temperature. The fatigue strength of semi-circular and v-shaped notch geometries are evaluated and the results compared with those of smooth specimens. The stress fields of the different geometries are analysed by use of analytical models and numerically by use of finite element. The fatigue data shows a smaller scatter in the geometries with printed overhangs than the ones without. High values of notch sensitivity is obtained for both notch geometries. Fatigue properties of AM Inconel 718 are so far underexplored, this research therefore adds to the applicability of this material and manufacturing method for load bearing applications.
关键词： Elastic Stress Fields,Additive Manufacturing,Fatigue,Notch,Inconel 718
更新于2025-09-12 10:27:22
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Cadmium sulfide quantum dots impact Arabidopsis thaliana physiology and morphology
摘要： The differential mechanisms of CdS QDs (Quantum Dots) and Cd ion toxicity to Arabidopsis thaliana (L.) Heynh were investigated. Plants were exposed to 40 and 60 mg L-1 for CdS QDs and 76.9 and 115.2 mg L-1 CdSO4·7H2O and toxicity was evaluated at 5, 20, 35 (T5, T20, T35) days after exposure. Oxidative stress upon exposure was evaluated by biochemical essays targeting non-enzymatic oxidative stress physiological parameters, including respiration efficiency, total chlorophylls, carotenoids, ABTS and DPPH radicals reduction, total phenolics, GSH redox state, lipid peroxidation. Total Cd in plants was measured with AAS. Root and leaf morphology and element content were assessed in vivo utilizing low-vacuum Environmental Scanning Electron Microscopy (ESEM) with X-ray microanalysis (EDX). This integrated approach allowed identification of unique nanoscale CdS QDs toxicity to the plants that was distinct from CdSO4 exposure. The analyses highlighted that CdS QDs and Cd ions effects are modulated by the developmental stage of the plant, starting from T20 till T35 the plant development was modulated by the treatments, in particular CdS QDs induced early flowering. Both treatments induced Fe accumulation in roots, but at different intensities, while CdS QDs was associated with Mn increase into plant leaf. CdSO4 elicited higher levels of oxidative stress compared with QDs, especially the former treatment caused more intense respiration damages and reduction in chlorophyll and carotenoids than the latter. The two types of treatments impact differently on root and leaf morphology.
关键词： oxidative stress,morphology,Arabidopsis thaliana,Iron,ESEM/EDX,CdS QDs
更新于2025-09-12 10:27:22
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Multifunctional single-layered graphene quantum dots used for diagnosis of mitochondrial malfunction-related diseases
摘要： Mitochondria are critical organelles in eukaryotes that efficiently generate ATP for various biological activities and any defect in the process of ATP synthesis may lead to mitochondrial dysfunction and directly link to a variety of medical disorders. Monitoring the ATP variations in cells is key for innovative early diagnosis of mitochondrial diseases. Herein, multifunctional single-layered graphene quantum dots (s-GQDs) with bright green emission were constructed, which exhibit strong binding a?nity for ATP and good mitochondria targeting ability. Using the proposed s-GQDs we successfully achieved to discriminate the primary smooth muscle cells isolated from the transgenic mouse (heterozygote Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) 2 C674S knock-in mouse) with mitochondrial disorders or their littermate controls, indicating s-GQDs as promising probes for the study of cell metabolism and mitochondrial malfunction-related diseases, and targeting endoplasmic reticulum stress is an effective way to modulate metabolic pathways relevant to SERCA 2 inactivity mitochondrial dysfunction.
关键词： graphene quantum dots,ATP,mitochondrial disorders,endoplasmic reticulum stress,sarco/endoplasmic reticulum Ca2+ ATPase
更新于2025-09-12 10:27:22
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Stress distribution in laser metal deposited multi-layer thick-walled parts of Ti-6Al-4V
摘要： The laser metal deposition is an additive manufacturing technology enabling the production of large scale complex parts without additional treatment like welding or machining. The study of the origin of the stress field during laser metal deposition is essential for solving a number of problems, including: the assessment of cold and hot cracking; prediction of the fatigue resistance, and the stress corrosion cracking. The quantitative study of transient and residual stresses in build parts is necessary for optimising the parameters of processing and post-production stress relieving heat treatment. Residual stress field in laser metal deposited 50-layer (4-pass per layer) wall of Ti-6Al-4V was analysed experimentally using neutron diffraction and numerically using finite element simulation. Long dwell time between passes and a rigid substrate was used in order to simulate conditions of large scale parts fabrication. An analysis of the calculated and experimentally measured residual stress field showed that near the edges of the buildup there is a region where all three components of stress field are tensile, and normal stress exceeds the yield stress by more than 25%. Moreover, normal plastic strain in this area are also tensile and reaches 2.5-3%. The longitudinal tensile stress closes to yield stress on almost the entire length of the several last layers near the top of the buildup. Residual stress field calculated using neutron diffraction data according to interplanar lattice distance obtained assuming plane stress approach has a satisfactory agreement with FE simulated results.
关键词： Neutron diffraction,Laser metal deposition,Simulation,Residual stress,Titanium alloy
更新于2025-09-12 10:27:22
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Pulse-Propagation Modeling and Experiment for Femtosecond-Laser Writing of Waveguide in Nd:YAG
摘要： In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG crystals with experimental validation. Stress-induced waveguides are written in Nd:YAG crystals using 515 nm, 300 fs pulses at a 1 kHz repetition rate. Waveguides having a mean propagation loss of 0.21 ± 0.06 dB/cm are obtained, which is lower than the previous reported values for Type-II waveguides written in Nd:YAG crystals. The modeling and experimental results consistently show that the modi?cation (waveguide track) depth increases with input energy. A detailed analysis is presented to control the modal properties of the waveguide in the context of UPPE simulation.
关键词： stress-induced waveguide writing,nonlinear pulse propagation,femtosecond laser writing,Nd:YAG crystal
更新于2025-09-12 10:27:22
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Preliminary outcome of non-ablative vaginal Erbium laser treatment for female stress and mixed urinary incontinence
摘要： Objective: This prospective study presents a preliminary result to compare the clinical ef?cacy of patients with stress urinary incontinence and mixed urinary incontinence using minimal invasive Er:YAG vaginal laser. Materials and methods: A total of 20 patients were included, in which were 10 patients with SUI and 10 patients with MUI (stress and urge incontinence), and underwent a 2940 nm Er:YAG laser with a special SMOOTH mode in an outpatient of?ce without anesthesia or postoperative medications. All patients completed two sessions of treatment with an interval time of 28 days. At three months after treatment, all patients were asked to a clinical visit for evaluate the clinical outcome by pre-treatment and post-treatment ICIQ-SF questionnaire. At pretreatment and 3 months after the completion of two therapy sessions, patients were asked to answer the ICIQ-SF questionnaire. The questionnaire consists of three scales for assessment of the treatment outcome of urinary incontinence as: no change (no change score), improvement (decrease score 1e5), and strong improvement (decrease score >5) for two groups of patients with SUI and MUI. All the results were compared by Student's t test with two way analysis of variance between the two groups. Results: A total of 20 patients presented with SUI symptom relief and improvement with treatment satisfaction. All 10 patients with SUI reported improvement after vaginal laser treatment, 70% with marked improvement and 30% with improvement. All 10 patients with MUI also had improvement, 40% with marked improvement and 60% with improvement. There was no statistically signi?cant difference in the treatment outcome between the two groups. Conclusions: Vaginal Erbium laser produce provides vaginal collagen remodeling and synthesis that may repair and restore the pelvic ?oor function. Despite of sample limitation and short follow up, this treating procedure presented a good and a safe clinical outcome in patients with SUI and with MUI by assessment of ICIQ-SF questionnaire.
关键词： Stress urinary incontinence,Er:YAG vaginal laser,Urge incontinence,Mixed urinary incontinence
更新于2025-09-12 10:27:22