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).

Prediction of the interpass temperature of a wire arc additive manufactured wall: FEM simulations and artificial neural network

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.

Material Flow Behavior on Weld Pool Surface in Plasma Arc Welding Process Considering Dominant Driving Forces

A systematic review of fatigue behaviour of laser welding titanium alloys

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.

Optimizations of extrusion semidie angle and fabrication of extrusion die

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.

CFD case studies on the acoustic performance and backpressure changes on modified reactive mufflers

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...

M. Arunkumar

Papers

Numerical prediction of temperature distribution and residual stresses on plasma arc welded thin titanium sheets