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Influence of laser weld shape on mechanical and fatigue behaviour of single lap laser welded joints
摘要： Traditional manufacturing processes, like arc welding and resistance spot welding, are still the main welding processes to join structural components used across the on/o?-road vehicle industry. Due to the abundance of data, experiences and insights over the decades of usage, lot of fatigue design data has been generated for different joint geometries produced using these methods. The laser welding process has excellent capabilities to join thin sheet metal structures with minimum heat input resulting into lower deformation and improved productivity that offers significant benefit as compared to the arc and resistance welding processes. However, due to the agility of designing joint configurations and limited availability of understanding regarding the fatigue behaviour of laser welded joints, the need arises for the fatigue design data. Most of the research presents the use of straight linear shape laser welds and limited knowledge exist regarding the influence of shape of laser welds on mechanical and fatigue performance of the laser welded joints. The laser welded joints produce small notch like radius at the root of laser weld which could act as a stress raiser causing early crack initiation. For this work, C-shape laser weld has been selected as the geometric shape in comparison to the straight linear shape of laser weld produced on a series of single lap joints. Detailed fatigue experimental investigation has been carried out for linear and C-shape laser welded joints tested in 3 different orientations with respect to the applied cyclic load and several different R-ratio’s and the results are compared. The metallurgical studies have been carried out to understand the failure mode and micro-hardness variations across the weld and heat affected zone. Further, the residual stress profiles have been compared for the C-shape laser weld with the linear welds using detailed X - Ray Diffraction based residual stress measurement.
关键词： Laser Weld,Ultra-high strength steel,C Shape,Crack propagation,High strength low alloy steel,Crack initiation
更新于2025-09-23 15:21:01
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Laser transmission welding of thermoplastic with beam wobbling technique using particle swarm optimization
摘要： Laser transmission welding is growing day by day with an increase of the uses of thermoplastic materials. This article presents the effect of various process parameters on weld strength and weld seam width obtained. The transparent polycarbonate and black carbon filled PMMA, each of 2.8 mm thickness have been joined by using low power laser. Here, effect of wobble frequency and wobble width are studied along with other process parameters. It is observed that weld seam width much depends upon the wobble width and the effect of wobble frequency is minimum. It has been observed that laser beam wobbling provides the greater weld strength by enlargement of joint area. Moreover, Beam wobbling plays a significant role to achieve better weld strength and weld width. Response surface methodology has been used to model the laser welding process parameters and responses of welding through regression analysis. The results of ANOVA reveal that the models formed appropriately predict the responses within the range of process parameters. A confirmation experiment has also been conducted to validate the results. A multi objective optimization has been used to find the optimum solution by Particle swarm optimization technique.
关键词： Polycarbonate,Acrylic,Low power laser,Weld strength,Beam wobbling,Particle swarm optimization
更新于2025-09-23 15:19:57
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Experimental and numerical study on laser welding of glass using a CO2 laser and glass fiber as filler material
摘要： Automated laser welding with filler wires for bridging gaps and for connecting complex devices has been established for different metal materials. In spite of that, it is still a challenge to transfer this welding process to the brittle material glass. Therefore, glass welding is often realized through a manual process by heating the glass with a gas flame. In addition, welding of non-rotational components requires filler material for gap bridging between the joining partners, which is applied manually today. This work presents an experimental and numerical study on laser welding of fused silica using glass fiber as a filler material to bridge gaps. The goal was to achieve a defined weld penetration depth and heat affected zone which is important for the production of optical elements. Therefore, a CO2 laser heats up the glass components as well as the glass fiber within a temperature controlled welding process. The numerical investigations were used to identify the general process window for welding fused silica. Within the experimental study, the process parameters, such as the defined welding temperature, laser focal spot size, and feed rate were varied to investigate their impact on the welding outcome. In addition, the impact of the filler wire coating on the material composition of the welded component in the joint zone was investigated. Compared to the manual process, laser welding with glass fiber as a filling material leads to a highly reproducible process enabling a high automation level.
关键词： fused silica,temperature controlled welding,heat affected zone,laser welding,glass fiber,filler material,glass,CO2 laser,weld penetration depth
更新于2025-09-19 17:13:59
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The normal and shear strength properties of laser lap weld
摘要： The study was aimed to clarify the shear strength and the normal strength properties of the lap joint. The welds were characterized with respect to hardness, tensile and fatigue properties. The test materials of this study were low strength carbon steel (LSS) and ultra high strength wear resistant steel (UHSS). The shear strength, perpendicular strength and fatigue resistance of the lap joint laser weld was determined by tensile and fatigue tests. The shear strength of the LSS weld was higher than the strength of the base material. The shear strength of UHSS weld was higher than the LSS weld. However, compared to strength of the base material of the UHSS the weld was weaker even though the weld was harder than the base material. The normal strength of the UHSS and LSS welds was over two times higher than the shear strength of the same welds.
关键词： Shear strength,Laser weld,Normal strength
更新于2025-09-19 17:13:59
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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