- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Numerical and experimental investigation on microstructure and residual stress of multi-pass hybrid laser-arc welded 316L steel
摘要： In multi-layer welding, the interaction between the weld beads had a great impact on the performance of the overall joint. Therefore, experimental research and thermal-plastic analysis of 316L stainless steel multi-layer hybrid laser-arc welding were performed. The reasonable heat sources were proposed to simulate hybrid laser-arc welding (HLAW) and laser beam welding (LBW). The simulation results of temperature field and residual stress distribution were both validated and in accordance with experimental measurements. On this basis, Combining the simulated results with the metallurgical analysis, the microstructure of multi-layer weld was divided according to temperature histories. The formation mechanism of feathery ferrite precipitated in the re-melting zone (RZ) was analyzed. The feathery ferrite could increase the micro-hardness of the interlaminar position of weld. Moreover, the residual stress along the multi-layer weld thickness direction was simulated and X-ray diffraction (XRD) measured, which indirectly demonstrated the size and orientation variation of the grains in the RZ.
关键词： Residual stress,Microstructure,FE analysis,Hybrid laser-arc welding
更新于2025-11-28 14:24:20
-
In-situ Measurements and Thermo-mechanical Simulation of Ti-6Al-4V Laser Solid Forming Processes
摘要： Residual stresses and distortions are two technical obstacles for popularizing the Additive Manufacturing (AM) technology. The evolution of the stresses in AM components during the thermal cycles of the metal depositing process is not yet clear, and more accurate in-situ measurements are necessary to calibrate and validate the numerical tools developed for its simulation. In this work a fully coupled thermo-mechanical analysis to simulate the Laser Solid Forming (LSF) process is carried out. At the same time, an exhaustive experimental campaign is launched to measure the temperature evolution at different locations, as well as the distortions and both the stress and strain fields. The thermal and mechanical responses of single-wall coupons under different process parameters are recorded and compared with the numerical models. Good agreement between the numerical results and the experimental measurements is obtained. Sensitivity analysis demonstrates that the AM process is significantly affected by the laser power and the feeding rate, while poorly influenced by the scanning speed.
关键词： Numerical simulation,Laser Solid Forming (LSF),Thermo-mechanical analysis,Additive manufacturing (AM),In-situ measurements of residual stresses
更新于2025-11-28 14:24:20
-
Effect of shielding gas flow on welding process of laser-arc hybrid welding and MIG welding
摘要： The influence of shielding gas on welding process of laser-arc hybrid welding (LAHW) and metal inert-gas welding (MIG) was investigated by the computational fluid dynamics analysis (CFD) and high-speed photography. The results show that the process stability of MIG under high gas flow rate is poorer than that of LAHW. And the force of gas flow Fg can hinder the droplet transfer, whether MIG or LAHW. But the vaporization-induced recoil force Fv in LAHW helps to reduce this kind of hindrance and keep the process stability. Next, it can be found that the shielded gas flow mode in the main welding area cannot be changed significantly by increasing the shielding gas flow rate, while high gas flow rate can increase the area of high argon concentration and benefit the spread of molten metal.
关键词： Welding process,Computational fluid dynamics analysis,Laser-arc hybrid welding,MIG welding
更新于2025-11-28 14:24:20
-
Effects of phase transition temperature and preheating on residual stress in multi-pass & multi-layer laser metal deposition
摘要： To investigate the influences of phase transition temperature and preheating on the residual stress of multi-layer and multi-pass laser metal deposition (LMD), the multi-layer and multi-pass LMD, with and without preheating, were performed using five kinds of alloy with different phase transition features, and their residual stresses were measured using the hole drilling method. A finite-element (FE) model incorporating the phase transition was developed based on experimentally obtained physical property data. The results demonstrated that the low-temperature solid phase transition has a tensile stress relaxation effect, which leads to the formation of a compressive stress area. This relaxation effect was observed to decrease with the increase of the phase transition temperature. The high-temperature solid phase transition has no significant tensile stress relaxation effect during the multi-layer and multi-pass LMD process, which is different from the single track LMD. when the solid phase transition temperature is low, the preheating can improve the uniformity of the stress field only to a certain extent. However, when the preheating increases the lowest temperature of the thermal cycle and makes it higher than the starting point temperature of the solid phase transition, the tensile stress relaxation effect of the solid phase transition can be brought into full play.
关键词： Finite element analysis,Preheating,phase transition temperature,Residual stress,Laser metal deposition
更新于2025-11-28 14:24:20
-
Optimizing Processing Parameters for Multi-Track Laser Cladding Utilizing Multi-Response Grey Relational Analysis
摘要： Multi-track laser cladding is the primary technology used in industrial applications for surface reinforcement and remanufacturing of broken parts. In this study, the influence of processing parameters on multi-track laser cladding was investigated using a Taguchi orthogonal experimental design. A multi-response grey relational analysis (GRA) was employed to identify laser cladding processing parameters that simultaneously optimize the flatness ratio of the coating and the cladding efficiency. The optimal parameters setting found by GRA were validated experimentally. Results showed that the flatness ratio and cladding efficiency were closely correlated to the overlap rate and laser power, where the overlap rate shows the most significant impact on the flatness ratio and the laser power shows the most significant impact on cladding efficiency. Results from the validation experiment were within one percent (0.97% error) of the predicted value. This demonstrates the benefits of utilizing GRA in laser cladding process optimization. The methods presented in this paper can be used to identify ideal processing parameters for multi-response multi-track laser cladding processes or other industrial applications.
关键词： orthogonal experimental design,grey relational analysis,multi-track cladding,laser cladding
更新于2025-11-28 14:24:20
-
A Comparative Study of Deformation Behaviors Between Laser-Welded Joints and Base Metal of Ti-22Al-24.5Nb-0.5Mo Alloy
摘要： The tensile deformation behaviors of laser-welded Ti-22Al-24.5Nb-0.5Mo alloy joints have been investigated at room temperature and 650 °C using in situ tensile analysis methods. The a2 phase had a significant influence on deformation behaviors of base metal at room temperature and 650 °C. The microcracks mainly nucleated in B2/a2 phase boundaries or within a2 phase and then propagated along B2/a2 phase boundaries subsequently. Compared with the plastic fracture of base metal, the fracture modes of the fully B2-phase fusion zone at room temperature and 650 °C were quasi-cleavage and intergranular fracture, respectively. While dislocation slips became foremost deformation mode in the fusion zone at room temperature, there were a great amount of slip bands on the surface of grains caused by the slip systems. The microcracks of fusion zone at 650 °C nucleated and propagated along the grain boundaries of B2 phase. Owing to the lack of grain deformation, the cross-slip bands were in small quantities on the surface of B2 phase grains.
关键词： in situ analysis,laser welding,deformation behaviors,Ti2AlNb alloy
更新于2025-11-28 14:24:20
-
FFT analysis of surface structures fabricated by laser interference lithography
摘要： This paper presents an FFT (fast Fourier transform) analytical method for the study of surface structures fabricated by laser interference lithography (LIL). In the work, the FFT analytical method combined with Gaussian fitting is used to determine the periods and pattern distributions of surface structures from frequency spectra. For LIL, the processing parameters of incident and azimuth angles can be obtained corresponding to the period and pattern distribution. This work facilitates the detection of micro- and nano-structures, the analysis of pattern distribution in engineering, and the processing error analysis of LIL.
关键词： surface structures,micro- and nano-structures,pattern distribution,laser interference lithography,FFT analysis
更新于2025-11-25 10:30:42
-
Accelerating single molecule localization microscopy through parallel processing on a high-performance computing cluster
摘要： Super-resolved microscopy techniques have revolutionized the ability to study biological structures below the diffraction limit. Single molecule localization microscopy (SMLM) techniques are widely used because they are relatively straightforward to implement and can be realized at relatively low cost, e.g. compared to laser scanning microscopy techniques. However, while the data analysis can be readily undertaken using open source or other software tools, large SMLM data volumes and the complexity of the algorithms used often lead to long image data processing times that can hinder the iterative optimization of experiments. There is increasing interest in high throughput SMLM, but its further development and application is inhibited by the data processing challenges. We present here a widely applicable approach to accelerating SMLM data processing via a parallelized implementation of ThunderSTORM on a high-performance computing (HPC) cluster and quantify the speed advantage for a four-node cluster (with 24 cores and 128 GB RAM per node) compared to a high specification (28 cores, 128 GB RAM, SSD-enabled) desktop workstation. This data processing speed can be readily scaled by accessing more HPC resources. Our approach is not specific to ThunderSTORM and can be adapted for a wide range of SMLM software.
关键词： super-resolved microscopy,high-performance computing,Automated image analysis
更新于2025-11-21 11:24:58
-
Single-cell redox states analyzed by fluorescence lifetime metrics and tryptophan FRET interaction with NAD(P)H
摘要： Redox changes in live HeLa cervical cancer cells after doxorubicin treatment can either be analyzed by a novel fluorescence lifetime microscopy (FLIM)-based redox ratio NAD(P)H-a2%/FAD-a1%, called fluorescence lifetime redox ratio or one of its components (NAD(P)H-a2%), which is actually driving that ratio and offering a simpler and alternative metric and are both compared. Auto-fluorescent NAD(P)H, FAD lifetime is acquired by 2- photon excitation and Tryptophan by 3-photon, at 4 time points after treatment up to 60 min demonstrating early drug response to doxorubicin. Identical Fields-of-view (FoV) at each interval allows single-cell analysis, showing heterogeneous responses to treatment, largely based on their initial control redox state. Based on a discrete ROI selection method, mitochondrial OXPHOS and cytosolic glycolysis are discriminated. Furthermore, putative FRET interaction and energy transfer between tryptophan residue carrying enzymes and NAD(P)H correlate with NAD(P)H-a2%, as does the NADPH/NADH ratio, highlighting a multi-parametric assay to track metabolic changes in live specimens.
关键词： Fluorescence Lifetime Imaging Microscopy (FLIM),single-cell analysis,NADPH/NADH ratio,NAD(P)H,redox,FAD,fluorescence lifetime redox ratio (FLIRR),NAD(P)H-a2%
更新于2025-11-21 11:24:58
-
Gaussian FRET two-hybrid assays for determining the stoichiometry of hetero-oligomeric complexes in single living cells
摘要： Here we integrate multiple Gaussian-functions analysis into fluorescence resonance energy transfer (FRET) two-hybrid assays (Gaussian FRET two-hybrid assay) to determine the stoichiometric ratios of intracellular hetero-oligomers in single living cells. This method adopts in multiple Gaussian-functions to fit the E-count histograms of both donor- and acceptor-centric FRET efficiency (ED and EA) images of a single cell for obtaining the peak values (EDi and EAi), thus yielding the corresponding stoichiometric ratios (EDi/EAi) of intracellular hetero-oligomers. We performed Gaussian FRET two-hybrid assay for living Hela cells coexpressing different FRET tandem plasmids, and obtained consistent results with the expected values. Gaussian FRET two-hybrid assay for cells coexpressing Bad-CFP and Bcl-XL-YFP reveals that Bcl-XL binds with Bad to form a hetero-oligomeric complex with a stoichiometry of 2:1 on mitochondria.
关键词： Multiple Gaussian-functions analysis,FRET imaging,Single living cell,Stoichiometry,Hetero-oligomeric complex
更新于2025-11-21 11:24:58