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Lightweight materials, such as titanium alloys, magnesium alloys, and aluminium alloys, are characterised by unusual combinations of high strength, corrosion resistance, and low weight. However, some of the grades of these alloys exhibit poor formability at room temperature, which limits their application in sheet metal-forming processes. Lightweight materials are used extensively in the automobile and aerospace industries, leading to increasing demands for advanced forming technologies. This article presents a brief overview of state-of-the-art methods of incremental sheet forming (ISF) for lightweight materials with a special emphasis on the research published in 2015–2021. First, a review of the incremental forming method is provided. Next, the effect of the process conditions (i.e., forming tool, forming path, forming parameters) on the surface finish of drawpieces, geometric accuracy, and process formability of the sheet metals in conventional ISF and thermally-assisted ISF variants are considered. Special attention is given to a review of the effects of contact conditions between the tool and sheet metal on material deformation. The previous publications related to emerging incremental forming technologies, i.e., laser-assisted ISF, water jet ISF, electrically-assisted ISF and ultrasonic-assisted ISF, are also reviewed. The paper seeks to guide and inspire researchers by identifying the current development trends of the valuable contributions made in the field of SPIF of lightweight metallic materials.

This paper presents soft computing-based modeling and multi-objective optimization of process parameters in single-point incremental forming (SPIF) of aluminum alloy sheet in order to obtain desired deformed shape with optimal formability satisfying multiple objectives. Response surface methodology and adaptive neuro-fuzzy inference system (ANFIS)-based models were developed to predict the responses based on the experimental data collected according to central composite design of experiments considering tool diameter, feed rate and step height as inputs, and outputs, namely forming wall angle, deformed sheet thickness and surface roughness. Inverse analyses were also performed to determine the set of input parameters to achieve desired outputs. Two different algorithms, namely back-propagation and hybrid, were employed to train the ANFIS in batch mode with the help of experimental data. The performances of the developed models were tested through real experimental data and also cross-validation methods. ANFIS trained by hybrid algorithm was found to be slightly better than that trained by the back-propagation algorithm in terms of prediction accuracy. Desirability function and a non-dominated sorting genetic algorithm were utilized for performing multi-objective optimization in SPIF, and the obtained optimal results were found satisfactory compared to the experimental data. The proposed approach could provide a reliable guidance for selection of suitable parameters in SPIF to achieve desired formed parts.

Fabricating three dimensional shaped surfaces from flat sheet metals by laser forming, both out-of-plane and in-plane deformations are required. This article presents the modeling of coupling mechanism activated laser forming of sheet metals based on experimental data for prediction and optimization of bending and thickening deformations. Experiments were performed based on a central composite design of experiments on coupling mechanism based laser metal forming process considering the input process parameters like laser power, scan speed and spot diameter, bending and thickening were taken as the outputs. Neural network and neuro-fuzzy system-based models were developed to carry out both forward and inverse modeling of the laser metal forming process under the coupling mechanism. Multi-objective optimization based on the non-dominated sorting genetic algorithm was used to obtain multiple optimal solutions to achieve different amounts of out-of-plane and in-plane deformations. The proposed method could guide for a suitable selection of the process parameters to produce three-dimensional shapes utilizing coupling mechanism-based laser forming using multiple laser line heating.

The present study deals with angular distortions generated in fiber laser welding of Ti6Al4V sheets performed utilizing pulsed mode of laser irradiations. Experiments were conducted considering laser power, scan speed, pulse frequency and duty cycle as input process parameters, and angular distortion measured in terms of out of plane bending was taken as the process output. A central composite design was employed for carrying out pulsed laser welding experiments. The angular distortion was modelled using the response surface methodology for correlating with the input process parameters. Angular distortion was observed to increase with the laser power and scan speed. Optimum values of laser pulse frequency and duty cycle were found for obtaining least angular distortion. The prediction accuracy of the developed model of angular distortion was found to be good. Then, the desirability function approach of optimization technique was used to determine the optimum process parameters for obtaining the minimum distortion. Optimal distortion value was verified by conducting experiments and results were found satisfactory.

In this article, deposition geometry and mechanical properties of Inconel 625 alloy fabricated by wire arc additive manufacturing (WAAM) using gas metal arc welding principle were investigated. Parametric study and optimization of deposition geometry expressed in terms of width, height and cross-sectional area, were carried out considering the input variables such as voltage, wire feed rate, travel speed, and gas flow rate based on Box–Behnken design of experiments and response surface methodology. Mechanical properties of WAAM Inconel 625 were investigated using tensile testing, microhardness tests and fracture morphology of deposited thin wall geometry of Inconel 625. Tensile tests of samples were prepared in different orientations showed anisotropy existed in mechanical properties of the deposited wall, and the tensile properties of longitudinal direction were seen to be higher than the other two directions. Also, the tensile strength of longitudinal direction was highest near-substrate region and successively decreased towards the built direction. Microhardness study in different locations of the deposited wall showed highest value at the bottom region and successively reduced values along the built direction. Fracture morphology and microstructures with compositional analysis were performed on the fabricated wall structure using SEM. The microstructures of Inconel 625 were composed of columnar dendritic structure and tensile specimen fractures showed sharp tearing edges and dimpled surfaces indicative of good layer bonding with ductile failure morphology.

This paper presents investigations on the manufacturing of three-dimensional functional metallic parts through melting and deposition of stainless steel 430L wire material by a metal inert gas welding technique. Experiments were performed on wire arc additive manufacturing following face centered composite design of experiments considering voltage, current, electrode wire material feed rate and welding speed as inputs for modeling single bead geometry in terms of bead width, height, and cross-sectional area. Response surface models were built using the collected experimental data. Performance of the models in predicting the responses was found satisfactory. Models of single bead geometry were employed to calculate void and post-processing in fabricating three-dimensional parts following raster scanning deposition of multiple layers considering the different degree of overlapping and build directions. The theoretically estimated values of void and post-processing were verified through fabrications of two three-dimensional shapes. It was shown that the void and post-processing could be controlled by suitable selection of process parameters, the degree of overlapping between two beads and build direction.

This article presents the investigations on deformation behavior in precision forming of thin sheet metal by laser pulses using finite element analysis. The temperature and deformation fields were estimated and analyzed in pulsed laser micro-forming of AISI 304 stainless steel sheet of rectangular and circular shape considering the effects of different process parameters such as laser power, spot diameter and pulse on time. Response surface models based on finite element simulation results were developed to study the effects of the process parameters on deformations for the rectangular and circular workpieces. The amount of deformation was increased with the increase in laser power and pulse on time, and it was decreased with the increase in spot diameter. The effects of pulse frequency and sample size on deformations were also explained. Experiments were conducted on pulsed laser micro-forming of stainless-steel sheet to validate the finite element results. The results of finite element simulations were in good agreement with the experimental results.

This paper presents numerical and experimental investigations on wire arc additive manufacturing for deposition of 430L ferritic stainless steel. Finite element analysis was used to predict temperature distribution for deposition of multiple layers in wire arc additive manufacturing. The transient temperature distribution and predicted by finite element simulation was in good agreement with the experimental results. A wall type structure was fabricated by deposition of multiple layers vertically, and deposited material was characterized by tensile testing and microstructure study. The microstructure of the deposited wall structure was investigated through optical microscopy and scanning electron microscopy (SEM) with EDS. The microstructure of deposited material was changed from fine cellular grains structure to columnar dendrites structure with the formation of secondary arm. It was found that the YS, UTS, and EL of the deposition direction were better than the build direction. The mechanical properties of the WAAM manufactured material was found comparable to that of the wire metal.

This article presents formability analysis of aluminium alloy 7075 thin sheets in single point incremental forming (SPIF) through prediction of forming limit curve (FLC) and maximum formable wall angle. Deformation instability method based on tool-sheet contact and non-contact zones in incremental forming was used for the prediction of limit strains for plane strain and equi-biaxial stretching strain path. FLC of the material was also determined experimentally, after measuring limit strains for deformed sheet through groove test for the process. Further, maximum forming wall angle of the material was determined for deformed sheet in a square pyramid shape. The theoretical limit strains predicted by deformation instability approach were compared to the experimental values. Theoretically, calculated limit strains were observed to be higher for plane strain path but approximately close for equi-biaxial strain path compared to experimental limit strains. The maximum formable wall was found to be 55˚ for the material in the process.

This article presents experimental investigations and machine learning-based analysis on depositions of super duplex stainless steel (SDSS ER2594) material in wire arc additive manufacturing (WAAM) considering the process parameters namely voltage, wire feed rate, torch travel speed, and gas flow rate. Deposition efficiency and surface height values of the accumulated material were measured to build machine learning models using artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS). The developed ANN model could predict the deposition efficiency and surface height with mean absolute deviations (MADs) of 8.9% and 16.1%, respectively. The MAD for prediction of the two responses for ANFIS model was found to be 6.1% and 14.9% as compared to the experimental data. Multi-objective optimization was also performed to obtain optimal solutions to achieve desired deposition results. Mechanical properties and microstructures of the deposited materials with optimal processing parameters were found comparable to that of the base materials.