Developments in non-conventional machining for sustainable production - a state of art review

Abstract

An Unusual Association of Aplasia Cutis Congenita with Twin Pregnancy and Maternal Varicella Case Report

We report an unusual case of aplasia cutis congenita associated with twin pregnancy and maternal varicella in first trimester, occurring over the extremity of one of the twin while other twin was perfectly normal

Advances in polymers based Multi-Material Additive-Manufacturing Techniques: State-of-art review on properties and applications

Recently, the demand and studies related with Multi-Material Additive Manufacturing (MMAM) is continuously increasing. To uncover the essential knowledge hidden in the current mess of research works, this study, based on a simple review methodology, helps to identify and discuss the current knowledge about: limitations of software and hardware, the interface bonding strength of dissimilar materials, polymer reinforcement with continuous fiber, polymer-based multi-materials, and future and challenges. The review method starts with a list of topics to check: MMAM of polymers, the bonding strength between materials, knowledge gaps, and new development lines in polymer applications. Then, it continues with the search procedure on electronic databases and the inclusion and exclusion criteria definition. Finally, to help the discussion and assessment, the information is collected in tables

Application of the Finite Element Method to the Incremental Forming of Polymer Sheets: The Thermomechanical Coupled Model and Experimental Validations

Single Point Incremental Forming (SPIF) is an innovative die-less low-cost forming method. Until now, there have not been viable numerical solutions regarding computational time and accuracy for the incremental forming of polymers. Unlike other numerical approaches, this novel work describes a coupled thermomechanical finite element model that simulates the SPIF of polymer sheets, where a simple elastoplastic constitutive equation rules the mechanical behavior. The resulting simulation attains a commitment between time and accuracy in the prediction of forming forces, generated and transmitted heat, as well as final part dimensions. An experimental test with default process parameters was used to determine an adequate numerical configuration (element type, mesh resolution, and material model). Finally, compared to a set of experimental tests with different thermoplastics, the proposed model, which does not consider complex rheological material models, shows a good agreement with an approximation error of less than 11% in the vertical forming force prediction

A technical overview of metallic parts in hybrid additive manufacturing industry

Additive manufacturing technologies have emerged as the promising alternatives of conventional manufacturing techniques. Conventional manufacturing techniques involves cutting and removal of material by mechanical procedures to achieve final product. Whereas, discrete chunks of material in any form are combined point by point and layer by layer for the fabrication of final product in additive manufacturing processes. Numerous advantages and inefficiencies of these manufacturing techniques are reflected in factors such as the design, fabrication, material properties and working condition etc. Therefore, development of a production technology by combining the benefits of both conventional and additive techniques is significantly important. “Hybrid Manufacturing” jointly apply additive and conventional production methods to attain final products. Hence, this short overview covers the operation aspects of both additive and subtractive manufacturing of metallic materials

Parametric optimization for cutting forces and material removal rate in the turning of AISI 5140

The present paper deals with the optimization of the three components of cutting forces and the Material Removal Rate (MRR) in the turning of AISI 5140 steel. The Harmonic Artificial Bee Colony Algorithm (H-ABC), which is an improved nature-inspired method, was compared with the Harmonic Bee Algorithm (HBA) and popular methods such as Taguchi’s S/N ratio and the Response Surface Methodology (RSM) in order to achieve the optimum parameters in machining applications. The experiments were performed under dry cutting conditions using three cutting speeds, three feed rates, and two depths of cuts. Quadratic regression equations were identified as the objective function for HBA to represent the relationship between the cutting parameters and responses, i.e., the cutting forces and MRR. According to the results, the RSM (72.1%) and H-ABC (64%) algorithms provide better composite desirability compared to the other techniques, namely Taguchi (43.4%) and HBA (47.2%). While the optimum parameters found by the H-ABC algorithm are better when considering cutting forces, RSM has a higher success rate for MRR. It is worth remarking that H-ABC provides an effective solution in comparison with the frequently used methods, which is promising for the optimization of the parameters in the turning of new-generation materials in the industry. There is a contradictory situation in maximizing the MRR and minimizing the cutting power simultaneously, because the affecting parameters have a reverse effect on these two response parameters. Comparing different types of methods provides a perspective in the selection of the optimum parameter design for industrial applications of the turning processes. This study stands as the first paper representing the comparative optimization approach for cutting forces and MRR

ASSOCIATION OF THE IMPACT OF POSTNATAL NUTRITION ON THE GROWTH OF PRETERM INFANTS

Objectives: The objectives of the study were to measure the actual daily amount of each nutrient (protein, glucose, and fat) energy and fluid as per current ESPGHAN guidelines for preterm infants and to analyze the role of nutrients at different gestational age on growth and weight of preterm infants. Material and Methods: An observational and prospective cohort study was conducted from January 1, 2018, to December 31, 2018. This study included all preterm infants born <34 weeks gestational age admitted in the neonatal intensive care unit during this period at Mahatma Gandhi Medical College and Hospital. A total of 120 preterm neonates were studied. Results: There were mean weight, length, and head circumference continues to rise till the study end. Mean energy at birth was also continues to rise till the end. Conclusion: In the study, proper nutritional supplement as per ESPHAGEN guidelines was used for the development of preterm infant. The study showed that there were statistically significant results with anthropometry parameters with preterm baby growth in all domains

Investigations on quality characteristics in gas tungsten arc welding process using artificial neural network integrated with genetic algorithm

Gas tungsten arc welding (GTAW) technology is widely used in industry and has advantages, including high precision, excellent welding quality, and low equipment cost. However, the inclusion of a large number of process parameters hinders its application on a wider scale. Therefore, there is a need to implement the prediction and optimization models that effectively enhance the process performance of the GTAW process in different applications. In this study, a five-factor five-level central composite design (CCD) matrix was used to conduct GTAW experiments. AISI 1020 steel blank was used as a substrate; UTP AF Ledurit 60 and UTP AF Ledurit 68 were used as the materials of two tubular wires. Further, an artificial neural network (ANN) was used to simulate the GTAW process and then combined with a genetic algorithm (GA) to determine welding parameters that can provide an optimal weld. In welding experiments, five different welding current levels, welding speed, distance to the nozzle, angle of movement, and frequency of the wire feed pulses were used. Using GA, optimal welding parameters were determined: welding current = 222 A, welding speed = 25 cm/min, nozzle deflection distance = 8 mm, travel angle = 25°, wire feed pulse frequency = 8 Hz. The determination coefficient (R2) and RMSE value of all response parameters are satisfactory, and the R2 of all the data remained higher than 0.65

Phase change material heat storage performance in the solar thermal storage structure employing experimental evaluation

One of the most investigated and broadly used mediums in the solar thermal storage systems is using phase change materials. In this research, a comprehensive performance test bench for solar thermal utilization system using a controllable heater to substitute different levels of solar input was established. The test bench is not limited by the weather and equipped with alternative heat storage tanks for different PCMs. The heat storage structure and the performance of paraffin in low temperature system was examined using numerical simulation method. The results showed that the heating power received by PCM was stable at 6–8 kW under the heating condition of 85 °C. At the stage of incompletely melting, the temperature difference between the inside and outside was as high as 31.6, which can reduce the loss of heat to a great extent