Topic
Spot welding
About: Spot welding is a research topic. Over the lifetime, 12491 publications have been published within this topic receiving 89845 citations. The topic is also known as: Spot_welding.
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TL;DR: In this paper, a solid state spot welding technique is developed, which utilizes laser induced shock waves to accelerate the flyer plate towards the base plate to obtain spot joining of similar or dissimilar metal plates.
43 citations
TL;DR: In this article, a review of the published models for the electrical contact resistance in the resistance spot welding process is presented and an inclusive comparison of the models is presented, where the combined effects of both constriction and film are considered as general models.
Abstract: Contact resistance is a complicated phenomenon and resistance welding significantly escalates its complexity. Interference of various parameters in resistance spot welding, despite extensive research in this field, still makes this process puzzling to the welding researchers. Various models have been developed to deal with the contact resistance, but more or less all of them end up with trial and error to yield an acceptable outcome. Quantifying the contact resistance is a critical problem in the modeling of the resistance spot welding. In this paper, the published models for the electrical contact resistance in the resistance spot welding process are reviewed. Since the total or dynamic electrical resistance is composed of bulk resistance and contact resistance, it is realized that contact resistance is the most essential factor in heat generation. The contact resistance, by itself, is composed of two parts, constriction resistance and film resistance. Some models have been proposed to explain the relationship for constriction resistance of a single point, while some of the other models have dealt with a number of points. In contrast with constriction resistance, few formulations have been suggested for film resistance. Meanwhile, in some models, the combined effects of both constriction and film are considered as general models. One key observation can be drawn from these studies, and it is that reported measurements have shown obvious discrepancies. Contact resistance modeling for simulation of resistance spot welding depends on the modeling of contact resistance after film breakdown. Therefore, mathematical modeling of the constriction resistance is the key to a comprehensive model of the contact resistance. Despite valuable studies that mainly are experimental, generally recognized model of contact resistance that can take into account all of the important influencing parameters has not been developed yet. This might be resulted from the complexity of contact resistance. In the previous studies, analysis of contact resistance is mostly qualitative rather than quantitative, because the performance of the films differs extensively. The major way to study the influence of diverse films has been experimental investigations. The electrical contact involves problematical interaction between contact members of complex geometry and it is not easy to model. Only for the constriction resistance of some simplified cases analytical models are available. In resistance spot welding, understanding the surface conditions, such as size, quantity, and distribution of contacting asperities, is very hard to find. Moreover, it is difficult to explain and describe the surface films precisely. Although the theoretical investigations have been provided for a long time, a useful and systematic model of dynamic resistance has not been presented yet. To provide the researchers in resistance spot welding and other related fields with a comprehensive account of contact resistance, this article reviews and analyzes the published works in this area. Also, an inclusive comparison of the models is presented.
42 citations
TL;DR: In this article, a fully coupled thermo-mechanical finite element model (FEM) model of the plunge phase of a modified refill FSSW was presented, and the simulation results included the temperature, deformation, stress, and strain distributions in the plates being joined.
Abstract: Friction stir spot welding (FSSW) is a solid state joining technology that has the potential to be a replacement for processes like resistance spot welding and rivet technology in certain applications. To optimize the process parameters and to develop FSSW tools, it is important to understand the physics of this complex process that involves frictional contact, high temperature gradients, and large deformations. This paper presents a fully coupled thermo-mechanical finite element model (FEM) model of the plunge phase of a modified refill FSSW. The model was developed in Abaqus/Explicit and the simulation results included the temperature, deformation, stress, and strain distributions in the plates being joined. An experimental study was also conducted to validate the temperatures predicted by the model. The simulation results were in good agreement with the temperatures measured in the experiment. Also, the model was able to predict in a reasonable fashion the stresses and plastic strains in the plates.
42 citations
Journal Article•
TL;DR: In this article, cracks are observed during resistance spot welding a commercial aluminum alloy AA5754, and mechanisms of cracking and healing are discussed in a Metallographic study of welded coupons revealed cracks located on only one side of a weldment in the heat-affected zone (HAZ), with respect to the welding sequence.
Abstract: The phenomenon of cracking was observed during resistance spot welding a commercial aluminum alloy AA5754, and mechanisms of cracking and healing are discussed in this paper Metallographic study of welded coupons revealed cracks located on only one side of a weldment in the heat-affected zone (HAZ), with respect to the welding sequence. Cracks are visible from longitudinal cross sections only. Some of them are partially or fully filled. Crack appearance and orientation are fairly repeatable and their intergranular characteristics and dendritic fracture surface morphology prove they were formed at elevated temperatures in the presence of liquid metal. The discussion of metallurgical factors considering the Al-Mg equilibrium phase diagram and the possible temperature histories of various zones in a weldment during spot welding elucidated the approximate conditions for cracking during spot welding and for mending the structure. A thermomechanical analysis revealed a high possibility for tensile stress huildup on the cracked side of the weldments as a result of material flow, thermal stress development and localized straining.
42 citations
Journal Article•
TL;DR: In this article, the fatigue behavior of the weld-bonded (combination of welding and adhesive bonding) aluminium joint was investigated as part of a study attempting to replace steel with aluminium in the lightweight vehicle structure.
Abstract: Fatigue behavior of the weld-bonded (combination of welding and adhesive bonding) aluminium joint was investigated as part of a study attempting to replace steel with aluminium in the lightweight vehicle structure. Aluminium 5754-H40 alloy and bis-phenol-A epoxy adhesive were used in specimen fabrication. Test results showed that weld-bonded aluminium has a slightly lower fatigue resistance than the adhesive-bonded aluminium (i.e., the presence of the resistance spot weld decreases the fatigue strength by 11% at 3 × 10 6 cycles) but a much higher fatigue resistance than the aluminium of weld-bonded aluminium occurred by either «nugget-through» where failure originated from the weld nugget, or «adherent-tearing» where failure started from the edge of adherend overlap. Statistical analyses of the test results of weld-bonded aluminium indicated that fatigue strength is not significantly affected by the failure modes
42 citations