Applied Mechanics and Materials Vol. 165

Abstract: The instability of petroleum prices in the world market has caused the price of fuel in Malaysia to increase, especially in the transportation sector. As an alternative, the transition to use hydrogen as fuel was already in the study and research on the ability of hydrogen profit for internal combustion engine in the technical aspect. The governments involvement in the research as source of energy has been undertaken by several government agencies such as MOSTI, universities and automotive manufacturing industries. These agencies are responsible for developing activities, mainly for commercialization. The development of hydrogen energy in this country focuses on the role of hydrogen that includes methods of generating, transporting, storage, production, and long-term planning. Diversity in the use of hydrogen for Internal Combustion Engine (ICE) can be applied through many ways; hydrogen as the primary fuel, hydrogen mixed with gasoline, hydrogen mixed with diesel, and hydrogen mixed with NGV. Compatibility acceptance of ICE with hydrogen as an alternative energy can solve many technical problems such as backfire, knocking, and the reduction of hydrocarbon, carbon monoxide and smoke contaminants during engine ignition delay.

Abstract: Aluminum alloy 7075 is a useful material in industry due to its light weight, high strength, and resistance to general corrosion properties. The drawback of this alloy is its susceptibility to stress corrosion cracking (SCC). From the previous research, it was found that retrogression and re-aging (RRA) heat treatment is able to improve the SCC resistance of this alloy. In this study, the mechanical properties and microstructure alteration due to RRA was studied. First, the tensile specimens are heat treated to T6 and then retrogressed at 165/185/205°C for 10/30 minutes followed by re-aging at 120°C for 24 hours. The retrogression methods are categorized as standard retrogression and oil retrogression. Next, the specimens were gone through tensile test, hardness test, and microstructure characterization by using SEM. From the mechanical test result, the tensile strength and hardness of the alloy decreased upon the increment of retrogression temperature and time. The highest tensile strength of 638.48 MPa was observed at oil retrogress sample at 165°C for 10 minutes which is slight higher than T6 sample. Besides, different phases of precipitation were reviewed by the Kellers etching process. Also, the volume fraction of η phase is increased upon increasing the retrogression temperature and time.

Abstract: In order to reducing emission of internal combustion engines and reducing fuel consumption nowadays, human try to discover efficient internal combustion engines and green engines to protect environment. From last years, there were technologies like turbocharger, hybrid electric and different ways of fuel injection into engine and some others that those were effective in that time. By developing technology human need more efficient engine than past. Also, those technologies have some drawbacks so necessity of new technology is sensible. The new technology that developed by EPA (Environmental Protection Agency). HHVs are hybrid vehicle that use pressurized fluid instead of electric power as alternative power source along with internal combustion engine. Hybrid hydraulic vehicles consist of two important part high pressure hydraulic fluid vessels called accumulators, and hydraulic drive pump/motors. These types of vehicles do not need batteries that use in electric vehicle and it is one of expensive part of HEVs.

Abstract: Fatigue crack propagation in two-dimensional rail track model under constant amplitude loading was analyzed using finite element method. The stress intensity factor was predicted using the displacement correlation method that was written in FORTRAN code and exported to Post2D to run the program and utilizing the singular elements around the crack tip area with automatic remeshing model. The fatigue crack propagation is modeled through the successive linear extensions under the linear elastic assumption. To simulate the propagation a single edge angled-crack was introduced to calculate the accurate values of stress intensity factors. The fatigue crack propagation for rail track under four point bend loading model was successfully simulated. The crack was initially propagated in direction inclined to the rail head surface but changed its direction 90° to rail head surface after certain crack length. The mix mode stress intensity factors were also successfully determined through the proposed model.

Abstract: A car is a wheeled motor vehicle used for driving and transporting passengers. Therefore, cars are one of the most important forms of transportation worldwide. However, high magnitude of whole-body vibration (WBV) that can be associated with the car may lead to various diseases and health problems, such as low back pain, in humans. This study intended to present the value of 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. In addition, this study is done to implements a newly developed statistical analysis method called I-kaz 3D to determine the vibration level accordingly. The high value of I-kaz 3D coefficient corresponds to the high VDV value and otherwise. This study was conducted on a national car. The WBV exposure was measured for 10 min. Data was collected using an IEPE(ICP^TM) accelerometer sensor connected to a DT9837 device, capable of effectively measuring and analyzing the vibration. The vibration results were displayed on a personal computer using a custom graphical user interface (GUI). From the results gathered, it is 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).

Abstract: This paper is aimed to investigate the fatigue assessment of aluminium alloy 6061specimen, one of the widely used aluminium alloys in the production of mechanical components. The alloy possesses the ability of critical failure caused by fatigue when they are subjected to dynamic responses in automotive-type components. The specimens were prepared according to the ASTM E606 and ASTM E1820 standards which were then subjected to two types of cyclic loading amplitude modes namely constant amplitude and random amplitude. The effort is initiated by implementing fatigue data editing approach for random amplitude signal, the conventional method, the finite element method (FEM) and fatigue assessment determination through the statistical method of root mean square (r.m.s) and kurtosis. The input and edited signal acquired will be analyzed for the prediction of the fatigue damage based on the strain model approaches, i.e. Coffin-Manson, Morrow and SWT. From the results obtained, both edited and non-edited signals load display the same amount of fatigue damage to consequently decrease the analysis duration. In addition, the FEM was found to be the best approach for estimating the fatigue life. This research has finally revealed that the higher cyclic load amplitude will only diminish the fatigue life of a specimen. Furthermore, this fatigue assessment study will look forward to improve structural engineering development in monitoring components and consequently access the damage prediction variable which could later be implemented to the manufacturing industry.

Abstract: Fuelling system is one of the crucial variables that must be focused on, in order to achieve good fuel efficiency and low engine out emissions. Fuel injection system seems a promising technology as a medium to supply suppressed fuel because of its high fuel delivery efficiency, enhanced fuel economy and reduced engine out emission. Port-fuel injection (PFI) system has been used widely on small four-stroke gasoline engine because of its simplicity compared to direct injection (DI) system. In this study, the effects of intake manifold angle of a PFI retrofit-kit to the engine performances and emission characteristics were investigated. Experimental works comprised wide-open throttle with variable dynamometer loads for two different angles: 90° and 150°. From this study, it was observed that 150° was the best angle, which produced high brake power (BP) and brake mean effective pressure (BMEP), brake specific fuel consumption (BSFC) and hydrocarbon (HC) emission.

Abstract: Due to the increasing of fuel price, a new approach for the vehicle propulsion system needs to be developed. One of the approaches is by applying an electric motor in the vehicle propulsion unit. A new in-wheel electric motor is designed using finite element software Opera2D. This electric motor is intended to be applied for a small electric vehicle with a maximum speed up to 60 km/h. The electric motor is directly connected to the wheel of the electric vehicle. The total mass of electric vehicle is about 200 kg and the electrical power is fully supplied by rechargeable batteries. The proposed motor is based on the radial technology and one types of motor are developed i.e. Permanent Magnet Synchronous Motor (PMSM) with different value of motor parameters. The better motor design will be implemented in the small electric vehicle. The torque, speed, and power of the developed electric motor are simulated using Opera2D after the actual electric motor dimension is created in the Opera2D. After the simulated results are obtained, then the next phase is to fabricate the actual motor using laminated steel iron, permanent magnet, and coils.

Abstract: Nowadays, the spoiler is fitted at the rear car to make the car looks sporty without taking any consideration to its shape and aerodynamic. This paper carried out other benefits of the rear spoiler respective to the engineering point of view. These study concerns about drag and lift forces were produced by spoiler using wind tunnel test and simulation computational fluid dynamics (CFD) analysis. The main objective of this project is to compare the performances between the two methods in order to determine the aerodynamics performance of three different types of spoiler. The results of C_L and C_D have been determined and compared for all the three spoilers including the baseline model as a reference. The result shows that the comparisons of all models have different value of C_L and C_D but the model of spoiler 3 is more than 5%.