ABSTRACTThis paper presents a circular recycling system for end-of-life tires (ELTs) under extended producer responsibility (EPR) by integrating Individual Producer Responsibility (IPR) and Industrial Symbiosis (IS). The system aims for sustainability and circularity in the tire industry, avoiding the detrimental effects of landfilling. It focuses on emission-free recyclers to create IS for ensuring environmental sustainability. Additionally, the system uses a “dynamic pricing strategy” to take-back ELTs from consumers. This paper also presents a “multi-period scenario-based nonlinear mixed integer programming” model to investigate the economic sustainability of the proposed system under uncertainty. Three different evolutionary metaheuristic algorithms, “genetic algorithm (GA)-based simulated annealing”, “GA” and a new variant of “particle swarm optimization” are used to obtain the solution of the model. Through a case study, it is found that the proposed system is economically sustainable and has the potential to aid in the successful implementation of EPR in the tire industry.

ABSTRACTAn insight study has been addressed to communicate the machining behavior of SS 431 in terms of tool wear rate (TWR) and chip study. Experimental investigation shows that cutting speed (VC) as the most significant parameter to have TWR for SS 431. At low VC 19.5 m/min, chip formed was continuous hairy structure with regular saw fractured morphology, principally promoted due to intensely concentrated shear bands between neighboring segments resulting from shear localized instability in the primary shear zone. 25.9 and 30.6 m/min produces continuous ribbon shape chip and twisted chip, respectively. At high VC 30.6 m/min, owing to high-temperature generation, shear deformation zone was softer and perfectively plastic with least chip contact length encouraged to produce least TWR. The parameters 30.6 m/min, 0.08 mm/rev, and 0.15 mm of VC, feed, and depth-of-cut found optimum to reach least TWR. Further ANN was exercised to predict TWR is good agreement with the experiments.

ABSTRACTDistillation is an energy-intensive non-stationary process represented using non-linear model equations and involves multiple objectives. For such processes, data-based multi-objective optimization methods are more suitable compared to conventional non-linear optimization methods. Therefore, a surrogate-assisted multi-objective optimization (SAMOO) approach is developed by hybridizing an artificial neural network (ANN) and genetic algorithm (GA) to simultaneously minimize the annualized capital expenditure cost (ACAPEX) and annualized operational expenditure cost (AOC) for the methanol separation process. The approach is then extended for operational optimization to maximize methanol purity and minimize heat duty. The Pareto optimal fronts obtained using the data-based SAMOO approach are found to be very close to the optimization results obtained using the actual physics-based Aspen Plus model. The coupling of the genetic algorithm and ANN modeling in SAMOO approach reduces the computing time of optimization by ∽ 50% with nearly the same results as that of the physics-based model.

ABSTRACTThe effect of polarity and shielding gases on the droplet transfer behavior and formation trend of cable-type welding wire gas metal arc welding was studied under the same welding parameters. An acquisition system was used to observe welding parameters, droplet transfer and arc behavior. The results showed that the arc shapes with different polarities under the same shielding gas were different. The arc length and width in direct current electrode positive (DCEP) mode were smaller than those in direct current electrode negative (DCEN) mode. For the same polarity and different shielding gases, with increasing CO2 gas content, the arc length and width gradually decreased. In DCEP mode, droplet transfer was characterized by globular and projected droplet transfer modes. The droplet transfer modes with different polarities differed under different shielding gases. The droplet transfer mode was basically the same for the same polarity. With increasing CO2 content, the weld bead formation gradually improved.

ABSTRACTIn this study, electrical discharge drilling (EDD) investigation of Si3N4-TiN ceramic composites is carried out. 25 experimental trials were performed by process parameters and performance characteristics using brass electrode were investigated. Multiple regression analysis (MRA) is employed to develop predictive models, and the validated findings show an accuracy of 90%. An integrated teaching learning based optimization (TLBO) and MRA is employed for simultaneous optimization of all responses. The outcomes were achieved with I = 7.0 A, Pon = 17.6 µs, Poff = 5 µs, DP = 17 kg/cm2, S = 5.0 m/sec, MRR = 0.1972 g/min, SR = 0.5194 µm, WR = 2.5371%, and MT = 0.3018 min. The validated result shows an error of 0.85%, 4.5%, 0.85%, and 4.1% for MRR, SR, MRR, and WR, respectively. Scanning electron micrographs have been proven experimentally, by combining the optimal parameters, to increase machining accuracy, geometrical tolerances, surface quality, and minimize micro-void frequency.

ABSTRACTIn January 2022 final electromagnetic stirrers were installed to improve billets’ macrostructure and to reduce defects in ŠTORE STEEL, Slovenia. From January to September 2022 the material from 1121 batches, out of 2284 batches produced, was examined using ultrasonic testing. Among these 1121 batches, 270 batches were detected with defects larger than 2.5 mm. Based on various metallurgical reports made from samples taken after an ultrasonic inspection, the root causes were found to be shrinkage porosity and segregations. Based on the gathered parameters from this period (chemical composition, casting parameters, cooling or heating parameters of billets), the occurrence of inner defects was predicted using logistic regression and genetic programming. The genetic programming proved to be better than logistic regression. Based on modeling results, optimization of the final electromagnetic stirrers position for 51CrV4 spring steel was conducted. Consequently, out of 41 examined batches, only 2 were detected with defects larger than 2.5 mm.

ABSTRACTNitrogen strengthened austenitic stainless steels are uneasy to machine. 22-13-5 stainless steel better known as Nitronic-50 is also not an exception. The current study deals with such an investigation where Nitronic-50 has been machined under varied cutting speeds, feeds and depths of cut and its machinability has been tried to be adjudged on the basis of cutting forces, apparent coefficient of friction, tool-tip temperature, chip reduction coefficient, flank wear width, chip morphology and surface roughness. It is seen that while using higher cutting speed-lower feed-higher depth of cut combination, tangential cutting forces were 18.83% and 29.57%, apparent coefficient of friction was 9.48% and 12.90%, tool-tip temperature was 11.02% and 22.31%, flank wear was 41.25% and 29.91%, and surface roughness was 22.91% and 24.27% lesser as compared to the higher values obtained with higher cutting speed-higher feed-higher depth of cut and intermediate cutting speed-higher feed-higher depth of cut combinations, respectively.

ABSTRACTReducing pulse duration is the sole effective strategy to improve the processing accuracy in ultra-short pulse electrochemical microfabrication. High cost and unsuitability in practical production also restrain its development. This study aims to propose a method based on sinusoidal signals with variable resistance. The bilayer capacitor cannot be fully charged to achieve a transient machining state. An equivalent circuit differential equation is established, and the resistance becomes an effective parameter to control the machining accuracy. The experimental result shows that the machining accuracy increases significantly with the increase in resistance. The approach is applied to machine microstructures and achieves sub-micron scale accuracy on a pure nickel sheet. The same superior machining accuracy can be obtained by machining microstructures on hard-to-cut superalloy plates.

ABSTRACTTiAl alloys with different Al atomic compositions, i.e. Ti45Al, Ti48Al, and Ti51Al, were produced via double-wire arc-based additive manufacturing by altering the aluminum wire feed rate. The microstructure and mechanical performance of deposited parts were researched. By changing the aluminum composition from 45 at% to 51 at%, the microstructure in the uniform area transforms from equiaxed α2/γ lamellar and near-lamellar colonies to dual-phase structures and near-lamellar colonies, the volume fraction of α2 phase decreases from 46.5% to 12.4%, and the total microhardness decreases from 411 to 356 HV. As the aluminum composition increases, the compressive strength presents an increasing trend first and then a decreasing trend, and the compressive ratio presents an increasing trend. The maximum compressive strength and compressive ratio in the vertical and horizontal orientations are 1822.5 MPa, 1732.5 MPa, 19.9%, and 20.2%, respectively.

ABSTRACTThe effect of cutting edge radius (rβ) on the chip formation mechanism during the finish turning of Ti6Al4V is studied. An increase in rβ decreases the cutting to thrust force ratio and produces lower chip thickness due to the increase in plowing zone depth. Larger radius tools produce thinner loosely curled chips whereas tightly curled thicker chips are formed for the unprepared edge tool (36 µm). As rβ increases, the chip flow angle (β) increases and free-flowing chips with reduced up-curl but increased side and lateral curl and consequently larger resultant chip curl radius are produced. The chip serration height to overall chip thickness ratio increases whereas chip core thickness reduces owing to the increased plowing action as rβ increases. Chip segmentation analysis reveals increased serration height, thermal instability, and shear localisation in the shear zone due to the increased ploughing effect beyond ~60 µm edge radius.

ABSTRACTA long batch process typically runs for several hours to produce different process outcomes. During the entire duration of the process, several sensor data are recorded involving complicated non-linear dynamics among process constituents, which are difficult to model. The users are often interested in predicting the eventual process outcomes well before the completion of the process so that the process can be terminated in case the predicted outcome is not as desired. Virtual Metrology (VM), a virtual property estimation procedure, has gained importance over the years as a supporting tool to address this problem. In this paper, we have proposed a generalized VM pipeline including a deep-learning model that can be scaled to support high-dimensional input sensors and outputs. The developed model is able to predict the end-results for an industrial problem with less than 10% error after about one-fifth of the total process-time.

ABSTRACTThis study introduces a new method for efficient and low-damage machining of Ti6Al4V: laser-assisted CBN belt grinding. The impact of laser power and grinding depth on the machining behavior of the material is investigated, the elemental distribution and chemical state of the ground surface are analyzed, and the removal mechanism of laser-assisted CBN belt grinding is described. The results show that increasing laser power will improve processing efficiency, enhance plastic material removal, and improve surface quality; the tangential grinding force is decreased by 63.5% and the normal grinding force is decreased by 72.6% at the maximum laser power; a large amount of Ti and N are present on the ground surface, and they are present in the form of TiN compounds. This study is a guide to the research on efficient and low-damage machining of hard-to-process materials like titanium alloys.

ABSTRACTClean-integrity processing of nuclear-grade AISI 316L austenitic stainless steel components finished by the wire brush and sequent flap discs is performed for high-performance manufacturing of the nuclear power plant equipment. Two steel wire brushes of AISI 304 austenitic stainless steel and 65Mn carbon spring steel are used for the grinding under a spindle speed of 550–2000 rpm. Sequent polishing is carried out by the flap discs using silicon carbide cloth under 2000 rpm. An equivalent pitting corrosion resistance to that of the original stainless steel in 3.5% NaCl solution is obtained for finished samples by the combined processes. The contaminants composition of ground stainless steel samples is determined by the redness degree of chromaticity inspection. The contaminants microstructure and finishing-induced microstructure are dependent on the impedance phase angle change in eddy current impedance diagrams. The surface clean-integrity of nuclear-grade stainless steel is characterized by the series of nondestructive evaluation methods.

ABSTRACTAmused with the blissful benefits of micro-textures, researchers consider it a promising option for improving cutting tool performance, especially during machining superalloys. Through this study, the machining performance of two homothetic and six hybrid micro-textured tungsten carbide inserts have been comparatively assessed while dry turning Inconel-718. Dimple and channel micro-textures were the two independent homothetic textures. Dimple and channel micro-textures with 0°, 45°, and 90° orientation angles and a combination of triangle, square, and dimples constituted six different hybrid micro-textures. Micro-textures were fabricated on the rake face of inserts using a Ti-sapphire fired, nanosecond pulsed, infrared fiber laser. Dimple and channel micro-textured tools at 90° texture angle on rake face performed exceptionally well. Improvements in average tool life, cutting forces, and surface finish have been reported. Adhesion and attrition were the predominant forms of tool wear. Chip morphology study revealed long helical and continuous but segmented chips.

ABSTRACTThis article demonstrates the electro erosion milling process in Al-SiC metal matrix composites. Material Erosion Rate (MER) and Tool Erosion Rate (TER) are measured which depict the productivity aspect of the process. Depth and width of the slots, surface roughness (Ra) is used to indicate the geometrical accuracy. Maximum MER (0.1097 mm3/min) is obtained at 5A. Maximum TER (0.65 µm/min) is obtained at 2.15A. Minimum Ra (2.13 µm) is obtained at 2.15A. Maximum MER (0.1194 mm3/min) is obtained at 100µs. Lowest TER (0.73µm/min) is obtained at 10µs. Lowest Ra (7.66µm) is obtained at Ton of 100µs. Jaya algorithm is used to optimize and create Pareto front from which the results are extracted and reported. Material removal mechanism has been detailed which includes melting / evaporating of matrix material, electrochemical dislodging of SiC grains. Better surfaces have crater diameters ranging from 40–50µm and the bigger craters are in the range of 100–150µm.

ABSTRACTOptimal composite bone plate is designed for Periprosthetic Femoral Fracture (PFF) fixation using genetic algorithm (GA) by hybrid and varying fiber orientation. The bone plate should allow higher displacement in axial direction and minimum movement in shear direction. Composite material is considered for the bone plate, the most important constraint in this design problem is that the axial movement and shear movement are limited to 2 and 0.5 mm, respectively. The simulated data from the finite element analysis (FEA) are used for creating the artificial neural network (ANN) surrogate models for the bone displacements in both the directions, which act as the objective functions for the GA-driven optimization in the multi-objective fashion. FEA is used to validate the solutions derived through the design optimization process. The FE simulations have shown only 10% deviation in the simulation output when compared to the achieved optimum solutions.

ABSTRACTFull-field simulations used to enhance the predictive capability of classical finite element models require the preparation of high-quality initial digital material representation (DMR) data. Depending on the selected method, such a procedure can be time-consuming and, in subsequent model runs, result in a significant increase in computational time. An unconstrained grain growth algorithm based on the random cellular automata (RCA) method can be used as a potential solution to provide high-quality DMR. However, the most time-consuming part of that approach, the neighbor-search algorithm, should be optimized from an algorithmic point of view before practical application in full-field analysis. Therefore, four neighbor-search algorithms dedicated to the RCA method were developed and benchmarked within the paper for the algorithm's complexity and impact of individual parameters on computational efficiency. The research has shown that significantly reducing RCA simulation time is possible with the properly developed neighbor-search algorithm and problem-specific code optimizations.

ABSTRACTTi-6Al-4 V ELI is an advanced titanium alloy used in different sectors. Being a hard-to-machine material, it is crucial to explore the machinability of Ti-6Al-4 V ELI. Boric acid powder mixed with deionized water is utilized as a dielectric to machine Ti-6Al-4 V ELI in electrical discharge machining (EDM). The effect of powder concentration (PC), current, and pulse-on time on material removal rate (MRR), tool wear rate (TWR), surface roughness (SR), and specific energy consumption (SEC) is evaluated. X-ray diffraction (XRD) analysis revealed the formation of TiO2, TiB, and Al2O3-like hard compounds over the surface. Scanning electron microscope (SEM) test indicates that there are more craters and globules on the surface machined in 5 g/l PC compared to that of 15 g/l PC. The overall evaluation criteria are designed to maximize the MRR and minimize the TWR, SR, and SEC by optimizing the variable parameters.

ABSTRACTThe present work concerns microchannel fabrication using magnetic-assisted electrochemical discharge machining on silica glass. The magnetic field regulates the process by controlling bubble formation and separation adjacent to the tool edge. Due to the applied magnetic and electric flux on the electrolyte and electrode interface, the Lorentz force impacts the bubble establishment and film quality. The fractional bubble coverage decreases with the magnetic field, which increases the current density and affects the discharge frequency. The analytical model is explored here to investigate the magnetic field influences on departure radius. A novel approach has been adopted to couple the Laplace and Navier stokes equations for studying the magnetohydrodynamic effect. The experimental and analytical results reveal that magnetic flux decreases the bubble departure radius. The regression model explains the impact of controllable factors on surface roughness, material removal rate, and width overcut. The multi-response optimization with the hybridization of response surface methodology and grey relation analysis technique provides the optimum value of material removal rate, width overcut and surface roughness as 1.2 mg/min, 0.046 mm, and 1.58 µm, respectively.

ABSTRACTThis experimental investigation introduced the gas metal arc welding-based additive manufacturing to deposit single-layered beads of ER70S–6 and 316 L stainless steel (SS). Different experimental conditions are generated through response surface methodology for illustrating the effect of wire electrode material and deposition parameters on bead characteristics. From parametric analysis, wire feed speed and torch speed are found to be the most controlling factors for bead width, height, deposition area, penetration depth, dilution, and contact angle. Deposition with 316 L SS wire exhibits minimal bead characteristic features than ER70S–6 because of high electrical resistivity that restricts excessive flow of arc current (low thermal energy development) and maintains the molten pool stability. Microstructural transformation from the continuous nature of δ-ferrite into an isolated core-like structure indicates the heat input’s role over grain refinement. X-ray diffraction depicts α-Fe and ϒ-austenite phases (with δ-Fe) in ER70S–6 and 316 L SS deposits.