Numerical prediction of temperature distribution and residual stresses on plasma arc welded thin titanium sheets
04 Mar 2021-International Journal of Modelling and Simulation (Taylor & Francis)-Vol. 41, Iss: 2, pp 146-162
TL;DR: The residual stresses are responsible for most of the failure of weldments in nuclear industry and the temperature distribution is the key measure to predict these residual stresses as discussed by the authors, and the residual s...
Abstract: The residual stresses are responsible for most of the failure of weldments in nuclear industry and the temperature distribution is the key measure to predict these residual stresses. The residual s...
Citations
More filters
TL;DR: In this article, the influence of idle time on the interpass temperature (IT) of 20-layer single-bead walls produced via wire arc additive manufacturing (WAAM) was analyzed using finite element method (FEM) simulations.
Abstract: Finite element method (FEM) simulations are a powerful tool for understanding the thermal–metallurgical–mechanical effects of wire arc additive manufacturing (WAAM). Nonetheless, owing to the multiphysical nonlinear nature of welding coupled with the longer deposition time of WAAM, FEM simulations can be laborious and time-consuming, which makes it difficult to simulate the numerous procedural parameters of WAAM. Therefore, the present work aimed to employ an FEM mode to analyze the influence of idle time (30–240 s) on the interpass temperature (IT) of 20-layer single-bead walls produced via WAAM and use the FEM results to develop a predictive model for the IT based on an artificial neural network (ANN). The FEM simulations were performed using a heat source and a 20-layer single-bead wall model that was experimentally calibrated and validated. The first layers exhibited similar energy accumulation; however, as the wall height increased, the IT rapidly increased under to low idle times (≤120 s). The ANN was trained using the FEM simulations results, validated with FEM results (not included in the training database), and used to establish a process map (including the idle time, number of layers, and IT). This can help the manufacturers to obtain a suitable balance between productivity (lower idle times) and part behavior (e.g., microstructure and mechanical properties).
12 citations
TL;DR: In this article, the effect of oxygen in the shielding gas on the material flow behavior of the weld pool surface was discussed to clarify the dominant driving weld pool force in keyhole plasma arc welding (KPAW).
Abstract: In this study, the effect of oxygen in the shielding gas on the material flow behavior of the weld pool surface was discussed to clarify the dominant driving weld pool force in keyhole plasma arc welding (KPAW). To address this issue, the convection flow on the top surface of weld pool was observed using a high-speed video camera. The temperature distribution on the surface along keyhole wall was measured using the two-color pyrometry method to confirm the Marangoni force activity on the weld pool. The results show that the inclination angle of the keyhole wall (keyhole shape) increased especially near the top surface due to the decrease in the surface tension of weld pool through surface oxidation when a shielding gas of Ar + 0.5% O2 was used. Due to the change in the keyhole shape, the upward and backward shear force compositions created a large inclination angle at the top surface of the keyhole. From the temperature measurement results, the Marangoni force was found to alter the direction when 0.5% O2 was mixed with the shielding gas. The shear force was found to be the strongest force among the four driving forces. The buoyant force and Lorentz force were very weak. The Marangoni force was stronger than the Lorentz force but was weaker than shear force. The interaction of shear force and Marangoni force controlled the behavior and speed of material flow on the weld pool surface. A strong upward and backward flow was observed in the case of mixture shielding gas, whereas a weak upward flow was observed for pure Ar. The heat transportation due to the weld pool convection significantly changed when only a small amount of oxygen was admixed in the shielding gas. The results can be applied to control the penetration ratio in KPAW.
11 citations
TL;DR: In this paper, a small review on the fatigue behavior of laser welding titanium alloys has been analyzed to enhance its mechanical properties, influence of process parameters, fracture mechanisms, and the strength-to-weight ratio.
8 citations
29 Oct 2020
TL;DR: In this paper, a pilot study has been conducted for selecting a suitable die design for the present work and the selection of the semidie angle has been determined for the die of inlet diameter 12.5mm and outlet diameter 8.1mm.
Abstract: Extrusion is the important manufacturing process and many components have been manufactured. Extrusion load play the major role for that the selection of die angle. A pilot study has been conducted for selecting a suitable die design for the present work. The selection of the semidie angle has been determined for the die of inlet diameter 12 mm and outlet diameter 8 mm. Hot die steel (H-13) is used as the die material for this study.
5 citations
29 Oct 2020
TL;DR: In this paper, the authors compared the stock muffler with new designs by considering transmission loss as the deciding factor since it is a property of the geometry alone and the more the transmission loss the better the muffler is at attenuating the noise generated by the engine.
Abstract: Nowadays the automobile industry is largely driven by designs that complies with the laws and regulations governed by environment concerns. For instance, to counter noise pollution designer came up with the idea of muffler that considerably reduces the noise produced by the engine. An effort has been made to try and compare different models of a reactive muffler through case studies after cumulatively incorporating various changes that are generally considered beneficial. This paper compares the stock muffler with new designs by considering transmission loss as the deciding factor since it is a property of the geometry alone. The more the transmission loss the better the muffler is at attenuating the noise generated by the engine. However, another important factor that should be considered when designing a muffler is the Backpressure it creates on the engine as backpressure negatively impacts its performance. The design with the highest transmission loss along with a controlled backpressure is declared as the most effective design.
2 citations
References
More filters
TL;DR: Based on the ABAQUS software, uncoupled thermal-mechanical three-dimensional and two-dimensional (2-D) finite element models are developed in this article to evaluate the transient temperature and the residual stress fields during welding.
517 citations
TL;DR: In this paper, a working envelope for the process using Ti-6Al-4V was developed, and regression models were calculated for total wall width, effective wall width and layer height.
434 citations
Journal Article•
TL;DR: The solution of a traveling distributed heat source on a semi-infinite plate provides information about both the size and the shape of arc weld pools as mentioned in this paper, and the results indicate that both welding process variables (current, arc length and travel speed) and material parameters (thermal diffusivity) have significant effects on weld shape.
Abstract: The solution of a traveling distributed heat source on a semi-infinite plate provides information about both the size and the shape of arc weld pools. The results indicate that both welding process variables (current, arc length and travel speed) and material parameters (thermal diffusivity) have significant effects on weld shape. The theoretical predictions are compared with experimental results on carbon steels, stainless steel, titanium and aluminum with good agreement. 25 references, 23 figures, 1 table.
364 citations
30 Aug 2013
175 citations
TL;DR: In this article, the authors used the lubricant film of nickel matrix with MoS2 self-lubricating material to obtain high surface quality for Ti-6Al-4V titanium workpiece.
Abstract: Electric hot incremental forming of metal sheet is a new technique that is feasible and easy to control to form hard-to-form sheet metals. In the present study, Ti-6Al-4V titanium sheet was studied because it was wildly used in the aeronautics and astronautics industries. Although Ti-6Al-4V titanium can be well-formed in high temperature, the surface quality is a problem. In order to enhance the surface quality, it is very important to select the proper lubricant. At the same time, because Ti-6Al-4V titanium has a lively chemical property, it is very important to choose a processing temperature range in order to acquire excellent plastic property and to prevent oxidation. Various lubricants were selected in processing to compare the effect, and some workpieces were formed at different temperatures to find the best forming temperature. The results show that using the lubricant film of nickel matrix with MoS2 self-lubricating material, Ti-6Al-4V titanium workpiece was formed with high surface quality, and the optimum thickness of composite coating is 20 μm for Ti-6Al-4V titanium sheet of 1.0-mm thickness. In fact, the lubricant film also does help to prevent oxidation of Ti-6Al-4V titanium sheet. The appropriate temperature range of Ti-6Al-4V forming with slightly oxidized is 500–600°C in processing, and the maximum draw angle formed in this range was 72°.
140 citations