Tribological behaviour and lubricating mechanism of tire pyrolysis oil

The four-ball tester was used in this analysis to demonstrate the lubricity of tire pyrolysis oil (TPO). The tribological performance of the tire pyrolysis oil was compared with diesel fuel (DF) and their blends, DT10 (TPO 10%, Diesel 90%) and DT20 (TPO 20%, Diesel 80%). A scanning electron microscope (SEM) was used to investigate the wear scar. In contrast to diesel fuel, TPO demonstrated better antiwear behaviour in terms of higher load-carrying capacity. DT10, DT20, and TPO’s wear scar diameter (WSD) was 22.35%, 16.01%, and 31.99% smaller than that of diesel at 80 kg load, respectively. The scanning electron microscope micrographs showed that the TPO and DT10 had less wear than their counterparts

Impact response of Kevlar/rubber composite

This study aims to investigate the impact performance of composite panels consisting of plain-woven Kevlar fabric and rubber matrix. A finite element (FE) model in conjunction with experimental tests was developed to simulate the response of neat fabric and composite under impact loading. Each warp and weft yarn of fabric was individually modeled and combined with rubber matrix network to form the composite. To understand the effect of natural rubber on impact resistance of Kevlar/rubber composites, two types of rubber with different formulation were considered and their mechanical properties were obtained by split Hopkinson pressure bar tests and assigned to the model. Numerical results showed good agreement with the experimental data for both neat fabric and composite. It was shown that rubber matrix improves the ballistic performance of Kevlar fabric by keeping composite flexibility. High hardness rubber matrix composite has higher energy absorption capacity compared to the low hardness rubber matrix composite, due to presence of stronger intermolecular chains. Additionally, deformation and damage mechanism of fabric and composite were investigated under impact loading. The results were presented, discussed and commented upon

Unprecedented Impacts of Aviation Emissions on Global Environmental and Climate Change Scenario

There has been a continuously growing trend in international commercial air traffic, with the exception of COVID-19 crises; however, after the recovery, the trend is expected to even sharpen. The consequences of released emissions and by-products in the environment range from human health hazards, low air quality and global warming. This study is aimed to investigate the role of aviation emissions in global warming. For this purpose, data on different variables including global air traffic and growth rate, air traffic in different continents, total global CO2 emissions of different airlines, direct and indirect emissions, air traffic in various UK airports and fuel-efficient aircraft was collected from various sources like EU member states, Statista, Eurostat, IATA, CAA and EUROCONTROL. The results indicated that in 2019, commercial airlines carried over 4.5 × 109 passengers on scheduled flights. However, due to the COVID-19 pandemic in 2020, the global number of passengers was reduced to 1.8 × 109, representing around a 60% reduction in air traffic. Germany was the largest contributor to greenhouse gas (GHG) from the EU, releasing 927 kt of emissions in 3 years. In the UK, Heathrow airport had the highest number of passengers in 2019 with over 80 million, and the study of monthly aircraft movement revealed that Heathrow Airport also had the highest number of EU and International flights, while Edinburgh had the domestic flights in 2018. These research findings could be beneficial for airlines, policymakers and governments targeting the reduction of aircraft emissions

Energy efficient parallel configuration based six degree of freedom machining bed

The process of material removal from a workpiece to obtain the desired shape is termed machining. Present-day material removal technologies have high spindle speeds and thus allow quick material removal. These high-speed spindles are highly exposed to vibrations and, as a result, the accuracy of the final workpiece’s dimensions is compromised. To overcome this problem, the motion of the tool is restricted, and multiple degrees of freedom are given through the motion of the workpiece in different axes. A machining bed configured as a parallel manipulator capable of giving six degrees of freedom (DOF) to the workpiece is proposed in this regard. However, the proposed six DOF machining bed should be energy efficient to avoid an increase in machining cost. The benefit of using the proposed configuration is a reduction in dimensional error and computational time which, as a result, reduces the energy utilization, vibrations, and machining time in practice. This paper presents kinematics, dynamics and energy efficiency models, and the development of the proposed configuration of the machining bed. The energy efficiency model is derived from the dynamics model. The models are verified in simulation and experimentally. To minimize error and computation time, a PID controller is also designed and tested in simulation as well as experimentally. The resulting energy efficiency is also analyzed. The results verify the efficacy of the proposed configuration of the machining bed, minimizing position error to 2% and reducing computation time by 27%, hence reducing the energy consumption and enhancing the energy efficiency by 60%

Capability Enhancing of CO₂ Laser Cutting for PMMA Sheet Using Statistical Modeling and Optimization

Laser cutting is a widely used manufacturing process, and the quality of the resulting cuts plays a crucial role in its success. This research employed the Design of Experiments (DOE) to investigate the impact of input process parameters on kerf quality during the laser cutting of 5 mm polymethyl methacrylate (PMMA) sheets. Response surface methodology (RSM) was utilized to model the relationship between the input parameters and the kerf quality, with regression equations developed for each response using the Design Expert software. A statistical analysis revealed the significant effects of high laser power, cutting speed, and focal plane position on kerf quality. Optimization, guided by the desirability function, identified optimal parameter combinations that offered the most favorable tradeoff among various responses. Optimal conditions were found to involve a high laser power, a cutting speed ranging from 4 to 7 mm/s, and a focal plane position at the center. Experiments indicated the suitability of the models for practical applications. An overlay plot analysis revealed a weak negative correlation between the laser power and the cutting speed, while the focal plane’s position could be adjusted independently