Volume 14, Issue 4

The thermal analysis of Modified 9Cr-1Mo steel plate during GTA welding is carried out using finite element method employing SYSWELD software. First, the simulation of bead on plate welds for 16 varying process parameter conditions by employing a double ellipsoidal heat source was carried out. Simulated bead on plate weld bead dimensions for the 16 welds were compared with the actual bead dimensions obtained experimentally. Then the simulation of GTA welding of square butt joint on 3 mm thick plates of dimensions 300 × 125 × 3 mm was carried out. The simulated thermal profiles were validated using thermocouple measurements. There was good agreement between the predicted and measured weld bead profiles and thermal cycles for square butt joint. The investigation on the effect of copper back up plate on the peak temperature and the cooling rate has revealed that the peak temperature decreased by 147 °C and the cooling rate increased by 35%.

Race tracking is movement of the resin along the sides, inside the mould in between the gaps of the preform and the mould; it is also the path of least friction in the flow. The issues related to design of the infusion set up to minimize the race tracking and methods of avoiding the race tracking during the infusion are highlighted in the paper. Presence of race tracking in a two-dimensional (2-D) radial infusion schemes, and the average increase in the thickness of the preform due to race tracking is evaluated here with different infusion strategy. Setups having the same material properties, and mould size are used for better comparison. The setup dimensional aspect for race tracking free infusion is also highlighted in the paper. Further numerical simulation of three different infusion strategies in the radial two-dimensional infusions is carried out to closely understand race tracking and its implications.

The present investigation deals with the determination of temperature profile and subsequent rates of cooling at certain points on the external surface along axis of an ERW pipe, during TIG welding. Two samples of different diameters of pipes of ASTM A 106 Gr. B, seamless type are selected for experimentation. The temperatures on the external surface at different locations on each of these seamless pipes (of different diameters) during welding have been measured with the help of digital pyrometers. The temperature variation along the axis of pipe from the weld arc has been presented. Thereafter, through separate analytical methods the temperature distribution across the external surface of the pipe for a given point heat source is theoretically calculated, and the results are compared with the previously found experimental values of temperatures. They are found to be well in agreement. Further, the rates of cooling of a pre-selected point on the pipe surface are experimentally and analytically determined under varying welding conditions and are compared likewise and are found to be in good agreement too.

The last decade has witnessed an increasing interest in the novel applications of electrical discharge machining (EDM) process. Due to the continuous efforts by the researchers many innovations have been made to improve the performance of EDM process. Among various EDM variants, powder EDM is one of the successful technique, which shows the considerable improvement in the performance of EDM by increasing the MRR and surface finish as both of these responses are mainly considered by the industries. Despite the better processing results, powder mixed EDM process is used in industry at slow pace. Therefore, with a vast future scope of powder EDM in areas of machining and surface modification of difficult-to-machine materials, authors in this paper explored all the parameters and terms related with powder mixed EDM process. The main aim of the paper is to help the researchers to understand this concept thoroughly and research the process parameters further in more details to get more improvements in the process resulting in achieving desired quality levels.

Resin bonded sand system is an emerging area, and it can be used to produce dimensionally accurate castings with good surface finish. In the present paper, experimental investigations are carried out on the resin bonded cores, to develop a non-linear mathematical model, using the concept of design of experiments. Subsequently, an artificial neural network (ANN) with four neurons each on input and output layers has been used to model the resin bonded sand system. It is important to note that the process parameters, such as percentage of resin, percentage of hardener, number of strokes and curing time are considered as inputs and the mechanical properties of the core, namely compression strength, tensile strength, shear strength and permeability are treated as the outputs of the network. It is to be noted that the performance of developed ANN depends on several factors of the network, such as type of transfer functions, coefficients of transfer functions, number of neurons in the hidden layer and connecting weights between different layers. In the present study, two population based search and optimization algorithms, namely genetic algorithm (GA) and artificial bee colony (ABC) are used for optimizing the parameters of ANN. It has been observed that both GA and ABC trained neural networks (that is, GA-NN and ABC-NN) are found to have good agreement with the experimental data and can be used effectively to model the resin bonded core sand system.