Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Department of Design and Automation

The conventional constant current arc welding of Hastelloy X (Ni-Cr-Fe-Mo) leads to the solidification and liquation cracks in the weldment. The higher heat supplied in constant current weldment develops the secondary carbide precipitates. It promotes the development of hot cracks in the weldment. In this study, joining of Hastelloy X plates was carried out by constant current gas tungsten arc welding (GTAW) and pulsed current gas tungsten arc welding (PCGTAW) with C263 filler wire. The result discovered that no hot cracks were formed in the weldment. In constant current mode, Cr-rich and Mo-rich Cr23C6 (M23C6), Fe2MoC, Fe3Mo3C (M6C), and Cr2Ti precipitates were observed. Whereas, in pulsed current mode, Ni3(Al, Ti), Ni3Ti, Co3Ti, Cr2Ti precipitates are found due to the segregation of Co, Al, and Ti. No Cr-rich and Mo-rich carbide phases identified in pulsed current weldment due to rapid cooling rate and higher thermal gradient observed during solidification. The tensile results revealed that 8.23% increase in the ultimate tensile strength and a 29.62% increase in elongation of pulsed current mode welding compared to constant current welding. Further, the microhardness and impact toughness of PCGTAW is 3.32% and 5.45% higher than GTAW, respectively. In pulsed current welding, better mechanical properties were identified compared to constant current welding. The nonappearance of Cr and Mo-rich phases and refined microstructure in the weldment are the main reason for better strength. © IMechE 2021.

World University root node

School of Mechanical Engineering

Vellore Campus

Department of Manufacturing Engineering

Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering

Prospects of pulsed current arc welding on aerospace grade Hastelloy X

In Malaysia, the majority of household electricity (45%) is consumed by air conditioning. Such high energy consumption is mainly caused by inefficient insulating materials with poor thermal performance. Hence, the selection of a thermal wall insulator with low thermal conductivity is vital to reduce the energy consumption. Utilizing agro waste based thermal insulation materials has become an efficient and economical method for energy efficient building. In this review, the standards required for an efficient thermal insulator have been addressed. Moreover, thermal, acoustic, physical and mechanical performance of oil palm empty fruit bunch fiber (OPEFB) and sugarcane bagasse fiber and their composites are described in detail. Optimal fiber loading and different surface modifications were reported to enhance the thermal performance, acoustic, physical and mechanical performance of composites. From the observations, it has been concluded that agro waste based OPEFB and bagasse fibers can act as an efficient thermal insulator, which will significantly reduce the excess utilization of energy and thus the costs. © 2020 Elsevier Ltd

Construction and Building Materials

Potential of oil palm empty fruit bunch (OPEFB) and sugarcane bagasse fibers for thermal insulation application – A review

The use of composites from the past few decades has been outstanding. Composites are becoming very popular due to their high specific strength. The main aim of this research is to analyze the behavior of the composite structure under low-velocity impact. In this paper, curved composite panels were studied under single and multiple impacts where impact analysis is done numerically. Numerical analysis includes finite element modeling and finite element analysis of the structure through Abaqus software. Different parameters were obtained, and the results of which include deformation, stress distribution, contact force, and energy absorbed by the structure. Numerical results were compared for different materials as well as impacts and are validated with literature data. © 2021, Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

Low Velocity of Single and Multiple Impacts on Curved and Hybrid Curved Composite Panel for Aircraft Applications

Fusion deposition modeling (FDM) is the most prevalent technique of additive manufacturing. This is for its practice in many applications. Polycarbonate (PC) reinforced acrylonitrile-butadiene-styrene (ABS) composite in 3D printing upsurges properties and crops better strength for components by 3D printing. A study on 3D printed (FDM) PC/ABS composite material was investigated in this paper. The influence of variations in material composition on mechanical properties such as hardness, flexural strength, and impact strength was studied. The proposed work aims at analyzing PC/ABS composite material by the FDM process in terms of mechanical performance, microstructural study, and their processibility. Specimens with three different compositions (10 wt%, 20 wt%, 30 wt%) polycarbonate (PC) reinforced in ABS were prepared. The best composition of polymer composite by FDM was proposed from their mechanical properties, and a microstructural study was done to trace the deviations in the impact strength of PC/ABS composite. The study evidences the compatibility of PC/ABS polymer composite. The hardness and strength of the composite are improved with a rise in polycarbonate (PC) content in the material. This exhibit excellent strength to the component at various compositions of polycarbonate reinforcement. Polymer composition contributes to producing intricate 3D printed components with various benefits and applicable for vast applications in many fields. © 2021. the Author(s), licensee AIMS Press. All rights reserved.

Fulltext

AIMS Materials Science

Experimental characterization of mechanical properties and microstructure study of polycarbonate (PC) reinforced acrylonitrile-butadiene-styrene (ABS) composite with varying PC loadings

The final drivetrain ratio is an essential part of a vehicle. It is responsible for providing the desired torque to overcome obstacles while maintaining the speed and acceleration of a vehicle. A vehicle must have an optimum gear ratio to obtain the desired velocity and acceleration. To achieve this, four different approaches were used considering the input parameters of a BAJA All-Terrain Vehicle (ATV). The traction received from the ground is calculated and plotted against velocity on different terrains. Further, a drivetrain was modeled in Simulink to obtain different parameters like vehicle speed, acceleration, and wheel slip. A range of gear ratios was obtained by following a similar trend of vehicle parameters that were best suited for improving vehicle performance. Graphs were plotted to compare the effect of various vehicle parameters, and an optimum gear ratio was obtained. Based on the obtained results, it can be concluded that a gear ratio ranging from 7.5 to 8.5 will provide the optimum ratio and exhibit a consistent trend of results. ©

SAE Technical Papers

Determination of Optimal Gear Ratio of BAJA SAE All-Terrain Vehicle

This work deals with the modeling of nonsmooth vibro-impact motion of a continuous structure against a rigid distributed obstacle. Galerkin’s approach is used to approximate the solutions of the governing partial differential equations of the structure, which results in a system of ordinary differential equations. When these ordinary differential equations are subjected to unilateral constraints and velocity jump conditions, one must use an event detection algorithm to calculate the time of impact accurately. Event detection in the presence of multiple simultaneous impacts is a computationally demanding task. Ivanov (Ivanov A 1993 “Analytical methods in the theory of vibro-impact systems”. Journal of Applied Mathematics and Mechanics 57(2): pp. 221–236.) proposed a nonsmooth transformation for a vibro-impacting multi-degree-of-freedom system subjected to a single unilateral constraint. This transformation eliminates the unilateral constraints from the problem and, therefore, no event detection is required during numerical integration. This nonsmooth transformation leads to sign function nonlinearities in the equations of motion. However, they can be easily accounted for during numerical integration. Ivanov used his transformation to make analytical calculations for the stability and bifurcations of vibro-impacting motions; however, he did not explore its application for simulating distributed collisions in spatially continuous structures. We adopt Ivanov’s transformation to deal with multiple unilateral constraints in spatially continuous structures. Also, imposing the velocity jump conditions exactly in the modal coordinates is nontrivial and challenging. Therefore, in this work, we use a modal-physical transformation to convert the system from modal to physical coordinates on a spatially discretized grid. We then apply Ivanov’s transformation on the physical system to simulate the vibro-impact motion of the structure. The developed method is demonstrated by modeling the distributed collision of a nonlinear string against a rigid distributed surface. For validation, we compare our results with the well-known penalty approach. © The Author(s) 2020.

JVC/Journal of Vibration and Control

Galerkin–Ivanov transformation for nonsmooth modeling of vibro-impacts in continuous structures

European union end of life vehicle directive mandates the use of more sustainable/recyclable materials in automotive industries. Thermoplastics matrix-based composites allow recyclability of composites at the end of life; however, their processing technology is more challenging than thermoset composites. Manufacturing process and mechanical testing of sustainable sandwich composite made from sustainable materials: flax, recycled carbon fiber, polypropylene, and recycled PET foam are presented in this article. High pressure compression molding with adhesive thermoplastic polymer film was used for manufacturing sandwich composite skin. The recycled PET foam core was integrated/joined with the skin using a thermoplastics adhesive film. A three-point bending test was conducted to compare the flexural properties. The results show that such sustainable sandwich composites will be an excellent material for truck side panel to operate in adverse wind/storm conditions. The sustainable sandwich composite can potentially be an excellent candidate for the fabrication of light-duty, lightweight, and low-cost engineering structures in automotive industry to meet the EU end of life requirements. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Journal of Composites Science

Sustainable sandwich composites manufactured from recycled carbon fibers, flax fibers/pp skins, and recycled pet core

Strain Wave Gear (SWG) or Harmonic Drive (HD) shows moderate performance under symmetrical involute teeth. Teeth interference, excessive teeth meshing, vibration due to improper teeth engagement are the major drawbacks of strain wave gear under symmetrical involute teeth. In the present paper, an attempt has been made to improve the performance of strain wave gear by replacing the symmetrical involute teeth with asymmetrical involute teeth. Present investigation finds that under ‘asymmetric toothed strain wave gear’, aspects such as teeth interference, teeth engagement and teeth contact stress of strain wave gear are improving clearly and as a consequence some other aspects such as individual teeth strength, load carrying capacity, tooth endurance are also improving inherently. In the present analysis for symmetrical teeth 20°–20° pressure angle and for asymmetrical teeth, three different combinations of pressure angles such as 25°–20°, 30°–20° and 35°–20° are taken. © IMechE 2021.

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

Performance analysis of asymmetric toothed strain wave gear

This research work utilizes the concept of recurrent strategy of neurons, which performs sequential tasks where the output and input data are dependent with each other. The major advantage of using recurrent neural network (RNN) for humanoid motion planning lies in spending the previous used long sequence information through memory. RNNs form direct cycles having internal state and form prime candidate for handling learning procedure. In this paper, long short-term memory (LSTM) RNN is implemented in humanoid robot to test the motion planning analysis. In the neural network model, the obstacle distances from robot’s location are fed as input parameters, and moving angle (MA) is obtained as the output parameter from RNN to guide the humanoid to reach the target with LSTM. Both simulation and experimental navigations are carried out through the developed technique. Probability plot between the simulation and experimental results is performed with normal distribution with comparison analysis. It is found that the results are satisfactory for humanoid navigation. The percentage of deviation between simulation and experimental results in terms of navigation variable is below 6%, which is in acceptable limit range. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Probability Plot Result Comparison with Recurrent Neural Network Approach for Path Navigation of a Humanoid in Complex Terrain

Recent advances in the development and application of bio-based (natural fiber and biopolymer) composites are gaining broad attention because the resulting polymer completely degrades and does not release harmful substances. In this study, natural fiber 3 D braided yarn textile PLA (Polylactic acid) bio-composites are developed by film sequencing followed by hot-press compression molding. Bio-deterioration and thermal stability of the composites are analysed for storage, machining, transportation, and in-service uses in different environmental conditions (compost and thermal). Composite samples with different fiber wt.% (0, 22, 44) are exposed to compost soil. Tensile testing is performed under different configurations to characterise the tensile properties. Prepared bio-composite specimens are evaluated for weight loss and reduction in tensile properties over soil burial time, to observe the rate of biodegradation of braided yarn textile bio-composites. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) is employed to analyse the biodegradability of the composites. To study the thermal stability of the prepared bio-composites thermogravimetric (TG) analysis is carried out. Results showed that biodegradability, tensile properties and thermal stability of the composites are enhanced significantly with the reinforcement of 3 D braided yarn fabric. © The Author(s) 2021.