Faculty Publications
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Item Multi-objective Optimization of FSW Process Variables of Aluminium Matrix Composites Using Taguchi-Based Grey Relational Analysis(Springer Nature, 2019) Prabhu B, S.R.B.; Shettigar, A.K.; Herbert, M.A.; Rao, S.S.Successful joining of aluminium alloys using friction stir welding (FSW) opens a new window research in extending this technique to join aluminium matrix composites (AMCs). Current research is focused on optimization of process variables for multiple responses simultaneously. Experiments were performed using tool pin profile, rotational speed (RS) and welding speed (WS) as ideal process variables for multi-objective optimization in FSW of AMCs. Tensile strength, macro-hardness and elongation are considered as multi-response behaviour. Grey relational grade for the chosen multiple responses are obtained using grey analysis. Analysis of variance was utilized to understand the influence of process variables on the grey relational grade. Analysis reveals that RS and WS were the most influencing process variables on the output responses. Confirmation experiments were performed at optimized process variables to validate the present study. Predicted values were in good agreement with the experimental results. © 2019, Springer Nature Singapore Pte Ltd.Item Influence of Process Variables on the Ultimate Tensile Strength of Friction Stir Welded AA6061 Matrix Composite(Springer Nature, 2021) Shettigar, A.; Prabhu B, S.R.; Herbert, M.A.; Rao, S.S.The present study is focused on the application of the friction stir welding process (FSW) to weld aluminium matrix composites (AMCs). Joints are formed by varying FSW process variables such as tool revolving speed (TRS), tool traverse speed (TTS) and the tool pin geometry (TPG). Influence of these parameters on the ultimate tensile strength (UTS) of the joints is investigated. Process variable optimization is done using Taguchi L18 orthogonal array design. Optimum process variables are determined and confirmed by confirmation tests based on the analysis of variance. © 2021, Springer Nature Singapore Pte Ltd.Item Mechanical Properties and Microstructural Characteristics of Friction Stir Welded Aluminium Matrix Composite(Springer Nature, 2021) Subramanya, B.; Shettigar, A.; Herbert, M.A.; Rao, S.S.Nowadays, friction stir welding process appears a promising technique to weld difficult materials by conventional welding techniques. Present study aims to analyse the significance of process variables on the mechanical behaviour of aluminium matrix composite joined by friction stir welding (FSW) technique. FSW is carried out at different welding conditions using conventional threaded cylindrical tool (TC). Microstructural study indicates several tiny reinforced particles are uniformly distributed in the nugget region. Recrystallization and grin refinement are observed in the weld area. Nugget region exhibits higher hardness compared to the base material. Joint efficiency of up to 89% is obtained for the FS-welded composite. The fracture surface reveals that the matrix undergoes a ductile fracture whereas reinforced particles exhibit brittle fracture. © 2021, Springer Nature Singapore Pte Ltd.Item Influence of welding process parameters on microstructure and mechanical properties of friction stir welded aluminium matrix composite(Trans Tech Publications Ltd ttp@transtec.ch, 2017) Prabhu B, S.; Shettigar, A.K.; Karthik, K.; Rao, S.S.; Herbert, M.In this study, the effect of process parameters on microstructure and mechanical properties of friction stir welded aluminium matrix composites(AMC) have been explored. The results indicated that the recrystallized grain size at the bottom of the weld region is smaller than that at the top region due to difference in the heat transfer at the weld region. The joint strength of AMCs depends on proper selection of process parameters like tool rotational speed and welding speed. If process parameter values are beyond the optimal value, the joint strength decreases due to formation of defects. Maximum tensile strength is obtained for rotational speed of 1000 rpm and welding speed of 80mm/min. © 2017 Trans Tech Publications, Switzerland.Item Application of neural network for the prediction of tensile properties of friction stir welded composites(Trans Tech Publications Ltd ttp@transtec.ch, 2017) Shettigar, A.K.; Prabhu B, S.; Malghan, R.; Rao, S.S.; Herbert, M.In this paper, an attempt has been made to apply the neural network (NN) techniques to predict the mechanical properties of friction stir welded composite materials. Nowadays, friction stri welding of composites are predominatally used in aerospace, automobile and shipbuilding applications. The welding process parameters like rotational speed, welding speed, tool pin profile and type of material play a foremost role in determining the weld strength of the base material. An error back propagation algorithm based model is developed to map the input and output relation of friction stir welded composite material. The proposed model is able to predict the joint strength with minimum error. © 2017 Trans Tech Publications, Switzerland.Item Experimental investigation of joint properties of friction stir welded aluminium matrix composite(Elsevier Ltd, 2021) Prabhu B, S.R.; Shettigar, A.; Herbert, M.A.; Rao, S.S.The present study is focused on welding of particulate aluminium matrix composites using friction stir welding process and investigating the influence of various process variables on the joint properties. The microstructural study and mechanical behaviors such as tensile strength and hardness of the weld zone were measured. Microstructural studies showed that process variables play pivotal role in refinement of grains. Compared to the top of the weld region, smaller grains were formed at the bottom due to variation in the heating effect. Measurement of the tensile strength and hardness of the weld zone, indicated that process variables plays important role in controlling the joint properties. Beyond the optimum range of process variables, the joint strength of welded part deteriorates due to the insufficient stirring and lack of plasticization leads to defect formation. Joint welded with traverse speed of 100 mm/min and revolution speed of 1200 rpm exhibited better mechanical properties. © 2021 Elsevier Ltd. All rights reserved.Item Microstructure and hardness of friction stir welded aluminium-copper matrix-based composite reinforced with 10 wt-% SiCp(Maney Publishing, 2014) Shettigar, A.; Veeresh Nayak, C.; Herbert, M.A.; Rao, S.S.In the present work, an attempt has been made to join aluminium-copper matrix-based composite reinforced with 10 wt-% SiCp, by the friction stir welding technique, at different combinations of tool rotational speed (710, 1000 and 1400 rev mm1) and welding speed (50, 63 and 80 mm min1) using square profiled friction stir welding tool. Welding parameters play a predominant role in improving the mechanical strength by minimising the defects. A good number of defect free joints were obtained at various combinations of rotational speed and welding speed. It has been observed that, rotational speed and welding speed have strong influence on microstructure, Vickers hardness and quality of welds. © W. S. Maney &Son Ltd 2014.Item Assessment of influence of process parameters on properties of friction stir welded Al-Ce-Si-Mg aluminium alloy(Institute of Physics Publishing helen.craven@iop.org, 2019) D’Souza, A.D.; Rao, S.S.; Herbert, M.A.The research on friction stir welding is mainly focused on welding of aluminium alloys. The material of interest in this research is an aluminium alloy known as Al-Ce-Si-Mg aluminium alloy. The FSW of this alloy finds applications in aerospace industry like joining of aircraft structure parts such as fuselage, cladding and engine components and in automotive industry for welding of parts of body structure and engine. The quality of the weld produced by FSW such as macrostructure defects, average grain size, ultimate tensile stress and weld zone hardness etc are dependent on input parameters like tool revolution, tool feed rate and tool pin profile. The weld defects like tunnel hole, worm hole and pin holes were not predominant in the tool revolution range of 800 to 1200 rpm and tool feed rate range of 10 to 20 mm min-1. The maximum ultimate stress was found to be lesser in the low and high tool revolution and tool feed rates compared to the medium speeds. The maximum value of UTS noted was 102.55 MPa for the weld at a tool revolution of 800 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool, giving a joint efficiency of 67%. The Vickers hardness values were less at lower and higher speed ranges of tool revolution and tool feed rates for all the tool pin profiles used. The maximum value of Vickers hardness was noted for a tool revolution of 1000 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool. The lowest grain size was observed for the tool revolution of 1000 rpm and tool feed rate of 20 mm min-1 with a triangular pin profile tool, indicating the inverse relation between hardness and grain size. In all the experiments it was observed that the triangular pin profile tool gives the best results at medium tool revolution and tool feed rate ranges. © 2019 IOP Publishing Ltd.Item Microstructure evolution and mechanical properties of friction stir welded AA6061/rutile composite(Institute of Physics Publishing helen.craven@iop.org, 2019) Prabhu B, S.R.; Shettigar, A.K.; Herbert, M.A.; Rao, S.S.Present study explores the Friction stir welding (FSW) of rutile reinforced AA6061matrix composite using various combination of tool traverse speeds (60, 75 and 90 mm min-1), rotational speeds (750, 1000 and 1250 rpm) and tool pin profiles (Threaded cylindrical and Square profiled pin). FSW process variables have significant impact in controlling the mechanical properties of the joint by limiting the welding defects. It has been inferred from the study that tool rotational speed and tool traverse speed majorly affects the microstructure, joint quality, hardness and joint strength. The weld area showed the presence of four distinct regions usually found in FSW of aluminium matrix composites. The weld region exhibited fine equiaxed grains and uniformly distributed tiny reinforced rutile particles. Tool having square profiled pin shows improved joint properties in comparison with tool having threaded cylindrical pin. © 2019 IOP Publishing Ltd.Item Evaluation of Microstructure, Hardness and Mechanical Properties of Friction Stir Welded Al–Ce–Si–Mg Aluminium Alloy(Korean Institute of Metals and Materials, 2020) D’Souza, A.D.; Rao, S.S.; Herbert, M.A.Abstract: A vast majority of the research on friction stir welding(FSW) is mainly focused on welding of aluminium alloys. The research studies in this paper are based on one such alloy known as Al–Ce–Si–Mg aluminium alloy, of which, the microstructure and other mechanical properties of the friction stir welded joints are yet to be studied. The plates of Al–Ce–Si–Mg aluminium alloy were friction stir welded using a non consumable, rotating tool with triangular profile pin and circular shoulder, with different combinations of tool rotation speeds and weld speeds. The microstructure, hardness and mechanical properties of the weld were analyzed. The microstructure of the weld zones revealed that, the average grain size at the bottom of the Nugget Zone (NZ) is 5 ± 0.12 ?m and gradually increases to 15 ± 0.23 ?m at the top of the NZ. In the TMAZ the grain size is 20 ± 0.14 ?m and is bigger compared to the NZ. In the HAZ, the grain size is around 37 ± 0.21 ?m and is bigger than that in the TMAZ. The maximum Vickers hardness value at the NZ center is 231.9 ± 2 Hv, and uniformly reduces to 100 ± 2.4 Hv in the TMAZ and 65 ± 1.3 Hv in the HAZ and then increases to 98 ± 1 Hv in the base material (BM). The maximum ultimate tensile strength (UTS) of FSW joint was found to be around 102.55 ± 3 MPa with elongation at fracture of 2.5%. The BM UTS was 154 ± 4.5 MPa. For a tool rotation speed of 800RPM and a weld speed of 20 mm/min a maximum joint efficiency of 67%. was obtained. Hence these were chosen as the optimum process parameters to join the alloy Al–Ce–Si–Mg by FSW. Graphic Abstract: [Figure not available: see fulltext.] © 2019, The Korean Institute of Metals and Materials.