Borigorla Venu

The present study aims to fabricate different Copper surface composites (Cu-SCs) such as Copper-Silicon Carbide (Cu-SiC), Copper-Boron Carbide (Cu-B₄C), Copper-Titanium Diboride (Cu-TiB₂) with enhanced mechanical properties using friction stir processing. The Cu-SCs were fabricated at different levels of tool rotational speed (TRS), traverse speed (TS), and Vol. % of micro-sized Boron Carbide (B₄C), Silicon Carbide (SiC), and Titanium Diboride (TiB₂) reinforcements using blind hole method. The mechanical characteristics such as ultimate tensile strength (UTS), yield strength (YS), percentage of elongation (%EL), impact toughness (IT), and microhardness (H) of the Cu-SCs were evaluated and analyzed. In the next stage, the process parameters were optimized using a graph theory algorithm and utility concept and the TRS, and TS were 1120 rev/min, and 40 mm/min respectively. The Cu-SCs fabricated by using taper threaded cylindrical tool pin profile at four Vol.% of TiB₂ possess enhanced the mechanical characteristics such as UTS, YS, % EL, IT, and H up to 282.07 MPa, 197.76 MPa, 12.96%, 16.67 J, and 168.6 HV. This was happened due to the increased recrystallization temperature, the pining effect, and restricting the grain boundary sliding. The microstructure in the stir zone of Cu-SCs fabricated with 4 Vol. % of SiC, 4 Vol. % of B₄C, and 4 Vol. % of TiB₂ particles exhibit fine grains. This is attributed to uniform distribution of the particles in the copper surface composites. The mechanical characteristics were also correlated with microstructures and fracture features.

Joining of Al-Cu based alloys such as AA2014-T651 is very difficult by fusion welding techniques due to liquefaction and solidification cracks. Therefore, solid state welding namely Friction Stir Welding (FSW) is most suitable to join these alloys. The main objective of this work is to identify the most influenced process parameters such as rotation speed of the tool, and tool traverse speed and their levels for fabricating the weldments by FSW process with using ultrasonic vibrations (UAFSW). A set of experiments were carried out using the plain cylindrical and taper threaded cylindrical tool pin profile at different levels of process parameters and experimental results were collected. A graph theory and utility concept was proposed and found an optimal working condition for better weldment properties. The UAFSW process enhanced the AA2014-T651 weldment mechanical characteristics at 1100 rev/min of tool rotation speed, and 40 mm/min of tool traverse speed. The tensile strength, yield strength, percentage of elongation, impact strength and micro hardness were found to be 431.69 MPa, 307.47 MPa, 11.66%, 8.32 J, and 139 HV respectively at optimal working condition. The weld joint obtained using a taper threaded tool pin profiled with ultrasonic vibration exhibits 95% joint efficiency compared to the weldments made by plain cylindrical taper tool pin profile with ultrasonic vibration. The measured characteristics have been correlated with microstructure and fracture features. The optimized responses were verified by the validation test.

This work focused on the optimization of process parameters, which may result in increasing mechanical properties of copper weldments. The different tool pin profiles such as plain taper cylindrical, taper cylindrical with threaded, triangular, square, pentagonal and hexagonal having constant shoulder diameters were used to fabricate the weldments. The experiments were conducted at different levels of tool rotational speed and weld speeds using six different tool pin profiles. The experimental results revealed that the defect free weldments could be obtained by using different tool pin profiles. From the investigation, it was found the weldments made by using a square (SQ) tool pin profile resulted in better mechanical properties compared to other tool pin profiles. Objective functions are developed for the mechanical properties in terms of input parameters. The input parameters of an SQ tool pin profile were optimized using a metaheuristic optimization based algorithm named teaching learning based optimization (TLBO) technique to improve mechanical properties. The TLBO suggests a combination of 900 rpm of tool rotation speed and 40 mm/min weld speed for better properties.

This study focuses on optimization of process parameters, which may result in improved mechanical properties of the friction stir weldments of AA2014-T651. Plain taper and threaded taper cylindrical tool pin profiles were used for the study. A set of experiments was conducted at different levels of tool rotational and weld speeds using two tool pin profiles. Mechanical properties such as tensile strength, yield strength, impact strength, percentage of elongation, and hardness were measured. Objective functions are developed for the five mechanical properties in terms of input parameters. The input parameters were optimized using teaching–learning-based optimization algorithm technique to improve mechanical properties. The teaching–learning-based optimization algorithm suggested three best combinations such as combination-I (940 r/min and 32 mm/min), combination-II (1100 r/min and 40 mm/min), and combination-III (1205 r/min and 45 mm/min). The optimization is also validated with experimental results.

The present energy scenario hydrogen fuel plays a dominant role in the power generation. Due to its unique characteristics of an extensive range of flammability, high flame speed, and diffusivity. In this present investigation, the diesel engine is converted into dual-fuel mode devoid of major conversions of the engine. The tests are performed on a dual-fuel mode and investigated the efficiency, emissions, and combustion features of the diesel engine. In the present context, hydrogen and biogas are injected from the inlet manifold as subsidiary fuel and diesel are injected as pilot fuel. The gaseous fuel injected in two different flow rates they are, 3 litres per minute (lpm), and 4lpm. The results from the experimentation revealed that the diesel with 4 lpm of hydrogen shows the 31.11 % enhancement of brake thermal efficiency but it shows 4.14% higher NOX emissions when compared with the pure diesel. But it shows. At the same time diesel with 4 lpm of Biogas exhibits 15.90% enhancement of brake thermal efficiency and 8.96% decrease in the NOX emissions in contrast to that of the single-mode of fuel with diesel.