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Articles by R.A. Bakar
Total Records ( 8 ) for R.A. Bakar
  R.A. Bakar and T. Firoz
  Computer software has been developed and described in the present study for thorough parametric analysis and design of a mechanical diesel fuel injection system. The method is based on the numerical solution of one dimensional, unsteady, incompressible flow equations through the fuel pipe along with appropriate initial condition, pump end boundary condition and nozzle end boundary condition. Method of characteristics was used to solve the mathematical model by using finite difference technique. Computer program has been written in Visual Fortran, which is capable of calculating pressure, velocity and other related parameters at different cam angles at any location of the fuel pipe, including pump and nozzle ends. First of all the numerical scheme was optimized and then its authenticity was verified by comparing its results with calculated and measured results available in the literature. The calculations by the present software were found to have improved agreement and acceptability. It was then used to make thorough parametric analysis of a typical fuel injection system. The results have been presented in the form of graphs.
  A.Z.M. Fathallah and R.A. Bakar
  Problem statement: Most concepts of linear engines were constructed as opposed pistons with complicated control devise to drive the engines. The advantage of the engines was their high overall efficiency. Approach: Although the efficiency was higher than conventional engine, however, it did not be applied yet, because the design of these engines was not only difficult to fabricate, but also it has little chance to compete the traditional engines in the market. Spring is adopted as a return force of the piston movement technique. Results: The unique of using spring as return cycle is the main characteristic of these engines. However, stroke of the engine is not constant as in the traditional engine. The problem is that, the expansion stroke is depending on thrust force of piston. On the other hand, the engine needs to operate in variable speed and load. This study is a prediction of the performance of both rotational and linear engines. Conclusion/Recommendations: The result of the examination can be used as return cycle design data of a single cylinder linear engine with spring device. As a result, the spring mechanism can be adopted to be used as return cycle in linear engine.
  A.R. Ismail , M.Z. Nuawi , N.F. Kamaruddin and R.A. Bakar
  The purpose of this study was to evaluate and validate the Daily Exposure to Vibration A(8) and Vibration Dose Value (VDV) experienced by the car driver, with care taken to elucidate the effects of WBV on the human body and all at once to introduce a newly developed real-time WBV measurement instrumentation. Cars are one of the most important transportation worldwide. It plays a significant role for the human to travel from one place to the other places promptly. However, high magnitude Whole-Body Vibration (WBV) that can be associated with car may lead to various diseases and health problems, such as lower back pain, in humans. This study was conducted on a national car. The WBV exposure was measured for 10 min. Data was collected using an IEPE (ICPTM) accelerometer sensor connected to a DT9837 device, capable of effectively measuring and analyzing the vibrations. The vibration results were displayed on a personal computer using a custom Graphical User Interface (GUI). MATLAB software was used to interpret the results and determine the WBV exposure level. The values of Daily Exposure to Vibration A(8) and the Vibration Dose Value (VDV) during one stretch of car travel were measured as 0.8778 and 3.8862 m sec-1.75, respectively. The results here confirm that WBV absorbed by the human body increases with an increase in the duration and magnitude of vibration exposure by the driver, illustrated by the increase in the value of Daily Exposure to Vibration A(8) and the calculated Vibration Dose Value (VDV).
  M.M. Rahman , K.I. Hamada , M.M. Noor , K. Kadirgama , M.A. Maleque and R.A. Bakar
  This study presents a comparative study of heat transfer characteristics in intake port for spark ignition engine using hydrogen and methane as a fuel. The fuels are led to the different behavior of physical processes during the engine cycle. One-dimensional gas dynamics was used to describe the flow and heat transfer in the components of the engine model. The engine model has been simulated with variable engine speed and equivalence ratio (φ). Engine speed has been varied from 2000 to 5000 rpm with increment of 1000 rpm, while equivalence ratio has been changed from stoichiometric to lean limit. The baseline engine model has been verified with existing previous published results. The obtained results are shown that the engine speed has the same effect on the heat transfer coefficient for hydrogen and methane fuel; while equivalence ratio is effect on heat transfer coefficient in case of hydrogen fuel only. Rate of increase in heat transfer coefficient comparison with stoichiometric case for hydrogen fuel are: 4% for (φ = 0.6) and 8% for (φ = 0.2). While negligible effect was found in case of methane fuel with change of equivalence ratio. But methane is given greater values about 11% for all engine speed values compare with hydrogen fuel under stoichiometric condition. The blockage phenomenon affects the heat transfer process dominantly in case of hydrogen fuel; however the forced convection was influencing the heat transfer process for hydrogen and methane cases.
  H.H. Habeeb , K. Kadirgama , M.M. Noor , M.M. Rahman , B. Mohammad , R.A. Bakar and K.A. Abouel Hossein
  This study discusses the development of first and second order of surface roughness prediction model when machining Haynes 242 alloy with Cubic Boron Nitride (CBN) at dry condition. The relationship between the cutting parameters (cutting speed, axial depth and feedrate) with surface roughness are discussed. Response Surface Method (RSM) has been selected to optimize the cutting parameters and reduce the number of experiments. Surface roughness obtained in these experiments ranged from 0.052-0.08 μm, which consider as an extremely fine finish. Increase in cutting speed from 70 to 300 m min-1, the roughness getting finer. On other hand, increase in feedrate (0.1 to 0.3 mm tooth-1) and axial depth (0.025 to 0.075 mm) surface roughness become rougher.
  M.M. Rahman , M.A.R. Khan , K. Kadirgama , M.M. Noor and R.A. Bakar
  This study presents the experimental investigation of the machining characteristics of austenitic stainless steel 304 through electric discharge machining. The effectiveness of the EDM process with stainless steel is evaluated in terms of the removal rate (MRR), the Tool Wear Rate (TWR) and the surface roughness of the work-piece produced. The experimental work is conducted utilizing Die Sinking electrical discharge machine of AQ55L model. Cylindrical copper electrode having a size of Ø19x37 mm and positive polarity for electrode (reverse polarity) is used to machine austenitic stainless steel 304 materials. The work material holds tensile strength of 580 and 290 MPa as yield strength. The size of the work-piece was Ø22x30 mm. Investigations indicate that increasing the peak current increases the MRR and the surface roughness. The TWR increases with peak ampere until 150 μ sec pulse-on time. From the experimental results no tool wear condition is noted for copper electrode at long pulse-on time with reverse polarity. The optimal pulse-on time is changed with high ampere.
  M.M. Rahman , A.K. Ariffin , S. Abdullah , M.M. Noor , R.A. Bakar and M.A. Maleque
  This study describes the finite element based fatigue life prediction of cylinder head for a two-stroke free piston linear engine subjected to variable amplitude loading, applicable to electric power generation. A set of aluminum alloys, cast iron and forged steel for cylinder head are considered in this study. The finite element modeling and analysis were performed utilizing the finite element analysis codes. The fatigue life analysis was carried out using finite element based fatigue analysis commercial codes. Fatigue stress-life approach was used when the piston is subjected to variable amplitude at different loading conditions. The effects of mean stress and sensitivity analysis on fatigue life are discussed. From the results, it was shown that the Goodman mean stress correction method is predicted more conservative (minimum life) results. It was found to differ significantly the compressive and tensile mean stresses. The compressive mean stress are beneficial however tensile mean stress detrimental to the fatigue life. The effect of materials and components S-N was also investigated and not found to give any large advantages, however the effect of certainty of survival was found to give noticeable advantages and it concluded that the 99.9% are fond to be design criteria. The proposed technique is capable of determining premature products failure phenomena.
  M.M. Rahman , M.K. Mohammed and R.A. Bakar
  This study was addressed the effect of speed on engine performance for four cylinder direct injection hydrogen fueled engine. GT-Power was utilized to develop the model for direct injection engine. This model was employed one dimensional gas dynamics to represent the flow and heat transfer in the components of engine model. Sequential pulse injectors were adapted to the inject hydrogen gas fuel within the compression stroke. Air-fuel ratio was varied from rich limit (AFR = 27.464) to a lean limit (AFR = 171.65). The rotational speed of the engine was varied from 1000 to 6000 rpm. The obtained results seen that the engine speed are greatly influence on the Brake Mean Effective Pressure (BMEP), Brake Specific Fuel Consumption (BSFC). It can also be seen that the decreases of BMEP with increases of engine speed, however, increases the brake specific fuel consumption. The brake thermal efficiency increases nearby the richest condition and then decreases with increases of engine speed. The optimum minimum value of BSFC occurred within a range of AFR from 38.144 (φ = 0.9) to 49.0428 (φ = 0.7) for the selected range of speed. The higher volumetric efficiency emphasizes that the direct injection of hydrogen is a strong candidate solution to solve the problem of the low volumetric efficiencies of hydrogen engine. Maximum brake torque speed for hydrogen engine occurs at lower speed compared with gasoline. The present contribution suggests the direct injection fuel supply system as a strong candidate for solving the power, torque and abnormal combustion problems.
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