Darius G. Solomon

Bio: Darius G. Solomon is an academic researcher from Universiti Teknologi MARA. The author has contributed to research in topics: Materials science & Brake. The author has an hindex of 2, co-authored 2 publications receiving 685 citations.

A review on current research trends in electrical discharge machining (EDM)

Abstract: Electrical discharge machining (EDM) is one of the earliest non-traditional machining processes. EDM process is based on thermoelectric energy between the work piece and an electrode. A pulse discharge occurs in a small gap between the work piece and the electrode and removes the unwanted material from the parent metal through melting and vaporising. The electrode and the work piece must have electrical conductivity in order to generate the spark. There are various types of products which can be produced using EDM such as dies and moulds. Parts of aerospace, automotive industry and surgical components can be finished by EDM. This paper reviews the research trends in EDM on ultrasonic vibration, dry EDM machining, EDM with powder additives, EDM in water and modeling technique in predicting EDM performances.

Characterization of Friction Material Formulations for Brake Pads

Abstract: New friction material formulations are compared with a commercial brake friction material used in Light Rail Transit (LRT) operating in Malaysia. Characterization techniques such as SEM, TGA, XRD, friction and wear tests are used to characterize the formulations as well as the commercial material. Out of the 30 formulations made, two formulations viz., S1 and S2 closer to commercial material are presented in this work. Formulation S2 exhibits better thermal stability and better wear resistance. With the help of SEM analysis, physical properties and XRD spectrum analysis, it is shown that formulation S2 has same crystallinity as the commercial specimen and can be considered for replacing the commercial material in LRT brake pad applications. The cost of the brake pad would reduce by half if they are made locally in Malaysia.

A Review on Geothermal Renewable Energy Systems for Eco-Friendly Air-Conditioning

Abstract: Nowadays, air conditioning consumes, on average, around one-fifth of the total power used in buildings globally. The present paper aims to provide the present status on the employment of Earth-to-Air Heat eXchangers (EAHX) to contain the consumption of energy and to reduce the effect on the environment in response to the Montreal and Kyoto protocols in a way to achieve cleaner energy production with a low Global Warming Potential (GWP) and a low ozone depletion potential (ODP). Different peculiarities and applications (direct or hybrid) are critically analyzed and reviewed. Specifically, in this paper, the different hybrid applications presented in the literature, where the Earth-to-Air Heat eXchangers are coupled to advanced systems, are reviewed. Finally, an IoT-based EAHX control system plan is reported and discussed to optimize energy efficiency and thermal comfort to suit operating conditions under different time zones.

Modeling and Simulation of Electric Motors Using Lightweight Materials

Abstract: Electric motors are utilitarian devices of great potential as they can limit the amount of pollution by drastically reducing the release of harmful gases. The implementation of the right type of advanced materials plays a vital role in the amelioration of modern automobiles while maintaining and/or improving the performance and efficiency of the electric motor. The use of lightweight materials could result in a better-performing vehicle that can be much less heavy. The replacement of regular cast iron, steel, and aluminum with lightweight materials such as fiber-reinforced polymer, carbon fiber, and polymer composites can reduce the weight of the motor without impacting its performance and improve its energy-saving capacity. This paper explores a way to reduce motor weight by employing a PA6GF30 30% glass fiber-reinforced polymer casing to reduce the weight of the motor while making cooling system modifications. This material was applied to the motor casing, which resulted in a significant reduction in weight compared to the water-cooled electric motor of aluminum (Alloy 195 cast) casing.

Aluminium-Silicon based metal matrix composites for brake rotor applications: a review

Abstract: In an automotive vehicle, the brake discs, also known as rotors, contribute significant weight to the engine chassis. Hence, lightweight aluminum brake discs are in the developmental stage as a popular alternative to traditional cast iron or steel brake discs. Weight reduction is desirable to improve vehicle performance and fuel efficiency. Monolithic aluminum is not a practical choice as an alternative to existing commercial brake discs because of its poor operational temperature and wear performance. Literature suggests that Aluminum Metal Matrix composite (AMC) can be an ideal choice for brake discs. AMC brake discs are more resistant to warping and cracking than cast iron discs. They also have better heat dissipation properties, which help reduce brake fade and prolong the life of the brake pads. This study examines the different types of aluminum alloys, reinforcements, and manufacturing processes for manufacturing ideal AMC brake discs. The significance of silicon as the principal alloying element to improve thermal characteristics and incorporate various reinforcements to increase the AMC's wear resistance and frictional stability for brake disc applications is outlined. This article focuses on the thermal and tribological behavior of the AMC brake discs' performance over traditional rotors. The review discusses the different equipment required to assess the tribological characteristics of brake discs to meet industrial requirements. In addition to experimental validation, this paper addresses the necessity of proper rotor design selection and numerical analysis to evaluate the thermo-mechanical behavior of the brake disc at various braking events. The article points out that aluminum metal matrix composites have great potential to replace conventional grey cast iron brake discs. Finally, this review discusses possible future research avenues for developing an AMC rotor disc.

Invited review article: high-speed flexure-guided nanopositioning: mechanical design and control issues.

Abstract: Recent interest in high-speed scanning probe microscopy for high-throughput applications including video-rate atomic force microscopy and probe-based nanofabrication has sparked attention on the development of high-bandwidth flexure-guided nanopositioning systems (nanopositioners). Such nanopositioners are designed to move samples with sub-nanometer resolution with positioning bandwidth in the kilohertz range. State-of-the-art designs incorporate uniquely designed flexure mechanisms driven by compact and stiff piezoelectric actuators. This paper surveys key advances in mechanical design and control of dynamic effects and nonlinearities, in the context of high-speed nanopositioning. Future challenges and research topics are also discussed.

Fabrication and Machining of Metal Matrix Composites: A Review

Abstract: Intrinsically smart, metal matrix composites (MMCs) are lightweight and high-performance materials having ever expanding industrial applications. The structural and the functional properties of these materials can be altered as per the industrial demands. The process technologies indulged in fabrication and machining of these materials attract the researchers and industrial community. Hybrid electric discharge machining is a promising and the most reliable nonconventional machining process for MMCs. It exhibits higher competence for machining complex shapes with greater accuracy. This paper presents an up-to-date review of progress and benefits of different routes for fabrication and machining of composites. It reports certain practical analysis and research findings including various issues on fabrication and machining of MMCs. It is concluded that polycrystalline tools and diamond-coated tools are best suitable for various conventional machining operations. High speed, small depth of cut and low feed ra...

Reliable multi-objective optimization of high-speed WEDM process based on Gaussian process regression

Abstract: The paper discusses the development of reliable multi-objective optimization based on Gaussian process regression (GPR) to optimize the high-speed wire-cut electrical discharge machining (WEDM-HS) process, considering mean current, on-time and off-time as input features and material remove rate (MRR) and Surface Roughness (SR) as output responses. In order to achieve an accurate estimation for the nonlinear electrical discharging and thermal erosion process, the multiple GPR models due to its simplicity and flexibility identify WEDM-HS process with measurement noise. Objective functions of predictive reliability multi-objectives optimization are built by probabilistic variance of predictive response used as empirical reliability measurement and responses of GPR models. Finally, the cluster class centers of Pareto front are the optional solutions to be chosen. Experiments on WEDM-HS (DK7732C2) are conducted to evaluate the proposed intelligent approach in terms of optimization process accuracy and reliability. The experimental result shows that GPR models have the advantage over other regressive models in terms of model accuracy and feature scaling and probabilistic variance. Given the regulable coefficient parameters, the experimental optimization and optional solutions show the effectiveness of controlling optimization process to acquire more reliable optimum predictive solutions.