Pusat Pengajian Kejuruteraan Mekanikal - Tesis
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Browsing Pusat Pengajian Kejuruteraan Mekanikal - Tesis by Type "master thesis"
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- PublicationA Model For The Fuzzy Front End Of New Product Development Process(2016-01)Abd Rahman, Md NizamIn general, New Product Development (NPD) methodology can be broken down into five phases, Strategic Planning. Idea Generation, Pretechnical Evaluation, Technical Development, and Commercialization. The first three steps are known as the front end and the last two are known as the back-end of the NPD methodology. The scope of this research work is limited to the first two steps of the NPD methodology, which are strategic planning and idea generation. The objectives of this research work are I) to piece together the various steps required in executing strategic planning process to ensure its effectiveness and 2) to define guidelines in selecting idea generation techniques that are suitable for a given set of conditions. Through analyzing case studies on thirty cornpapies that have been proven successful in NPD programs, the main factors that have significant impact on the success of NPD strategic planning process are verified and guidelines for selecting suitable idea generation techniques for a given set of conditions are developed.
- PublicationDevelopment and performance analysis of hydraulic hybrid regenerative braking system for passenger vehicle(2022-01-01)Idris, Khairul AnuarThe global fuel consumption of passenger vehicles has been rising dramatically over time. Since fossil fuel is non-renewable energy, there is a need to improve the passenger vehicles efficiency. Therefore, the hydraulic regenerative braking system (HRBS) is introduced to recapture the lost energy during the deceleration. This study aims to develop HRBS and determine its performances. The experimental work involved designing and fabricating a test rig of the HRBS in a parallel configuration. The performance of the developed system was determined in terms of efficiencies of hydraulic motor and pump. The study findings developed a mechanical efficiency map for the hydraulic motor for different pressures. It was found that the efficiency gradually increased with the increase in pressure from 20 to 80 bar, but a slight drop was seen with further increase in pressure above 80 bar. The highest efficiency recorded by pump and motor were 83 % and 74 %, respectively. Meanwhile, hydraulic pumpās mechanical efficiency maps in terms of pressure were determined for four different speeds. The efficiency was steadily increasing from the pressure 20 to 75 bar. The optimum operating pressure was 65 bar for both the pump and motor. The optimum operation also played a crucial role in establishing the higher mechanical efficiency for the motor and pump, subsequently affecting the overall performance of the developed HRBS system.
- PublicationEncapsulation process of polymer for led packaging(2021-12-01)Alim, Md. AbdulSeveral developments and innovations have reported strengthening the reliability and efficiency of these devices to speed up the LED packaging industry for the past few years. To develop a sustainable LED packaging process, die attachment and encapsulation shape are key factors. Epoxy based non-conductive adhesive (NCA) is popular die attachment material. Though NCA have many benefits so, an investigation on the suitable shear strength, adhesive thickness, and adhesion area are essential for die attachment process. Normally, high viscous epoxy resin is used as encapsulation material. A proposed low viscosity epoxy encapsulation shape can represent a new milestone for low-cost LED fabrication. In this work, the relationship between adhesive thickness and shear strength developed in chip and substrate joint is evaluated by using different adhesive applicator. Surface morphology of chip and substrate are also studied by using the SEM, EDS, and image processing software. The result indicated that the suitable shear strength 37.42 N/mm2 obtains at 24 Āµm thickness of the adhesive layer. A new moldless dispensing method for forming dome shaped encapsulation is studied. Luminous intensity of LED is determined by mixing verity of weight % of phosphor with the epoxy and variation in shape of encapsulation The results show that this method can produce the lenses with high aspect ratio (height over radius) on substrates of different sizes. The improvement of light output was found about 2.37% for dome shaped (average H/R value 0.71) encapsulation. This experimental work is a good guideline to master the geometric shape of encapsulation for further development and to choose technological criteria for LED packaging.
- PublicationFinite element modeling of warpage molded printed circuit board in a reflow process(2022-05-01)Sek, Chun HeiA printed circuit board (PCB) consists of multi-layer materials that allow electrical current flow. Each material layer has its own specific coefficient thermal expansion (CTE), such as Youngās modulus, Poissonās ratio, etc. A conventional PCB board consists of polymer, silicon, copper, and dielectric. With each layers having different CTE values, this causes PCB to warp.In the semiconductor industry, PCB warpage has greatly impacted assembly process yield and solder joint reliability. The present study explores the warpage changes of molded PCB during the reflow process. Warpage behavior on molded PCB models has been investigated experimentally and numerically. Experimental set-up employs Shadow MoirĆ© technique to measure real-time warpage measurement for a benchmark model with the size of 10 Ć 10 Ć1 mm. Temperature profile with progressive heating from 25 ā to 300 ā with an interval of 50 ā is employed. Then, the sample undergoes a cooling process until it reaches the room temperature. Numerically, ANSYS FEA simulation was carried out to investigate the warpage on different sizes of PCB models. In addition, thermal stress induced by CTE mismatch is studied to understand its impact on PCB warpage. The results revealed that the experiment and the FEA simulation results are in a good agreement, in particularly at the peak temperature of 300 ā, with less than 5 % deviation between both results. Moreover, the overall package warpage had also been influenced by package size in the reflow temperature. In addition, the results lead to the suggestion that the thermal stress exerted on the contact surface between different material types could lead to PCB warpages. The present research has established FEA that obtaining good warpage prediction model. The insights attained from this study would be beneficial for PCB design improvement, by optimizing materials and dimensions of PCB, in the attempt to minimize the warpage occurrence.
- PublicationMoisture diffusion during solder reflow processes of electronic packages(2022-01-01)Elwin Heng, Chia JieThe modern electronic packages has evolved and become so complex while the size has continued to shrink. packages continues to shrink. As a result, modern days electronic has become complex in manufacturing yield and reliability defect has become a huge concern. Moisture induced quality and reliability defect are not new to electronics industries. But the complexity of the modern days packages has caused moisture induced defect to become a huge concern. Hydroscopic materials in electronic packages are capable to absorb moisture upon exposure to environment throughout storage, manufacturing process and transport phase. Although moisture is supposed to be desorb when going through high temperature reflow process, but the presences of hydrophobic material in the structure could possibly obstruct and hinder the moisture desorption, causing residue moisture to continue reside in electronic packages. The internal moisture will develop high internal vapour pressure when going through high temperature loading. This vapour pressure can cause void, delamination, cracking to electronic packages internal structure, which can be detrimental to electronic packages. The moisture diffusion is very difficult to be analyse as electronic packages often made up from multiple components with different material properties, causing the moisture diffusion very difficult to be modelled can calculated. This paper will utilize Direct Concentration Approach (DCA) to model the moisture diffusion accurately to analyse the effect from moisture diffusion. Aside from the pressure develop from moisture, the high temperature subjected to electronic packages will also causing thermal stress. The typical electronic package with hydrophobic material could obstruct moisture desorption and causing moisture residue found to be 36% higher in vapour pressure compared to bi-material model, going beyond saturate vapour into superheated vapour or compressed liquid, which expose electronic package to higher pressure. The maximum Von-Misses syress induced by moisture significantly increase on package with hydrophobic material by 115% compared to model with hydrophilic material. With the use of Direct Concentration Approach, the effect of moisture diffusion and coupling with thermal stress in the aspect of Fluid Structural Interaction will be able to be studied.
- PublicationNumerical Simulation And Experimental Investigations On The Effect Of Polypropylene Rheology In The Injection Molding Process(2014-11)Rusdi, Mohd SyakirinThe design and fabrication of the mold are costly for the injection molding machine. Prior to the fabrication process, the prior to molding analysis is important to investigate the flowability of molten plastic in the mold design. The pre-molding analysis is carried out using simulation software, with the purpose to reduce the fabrication cost and time. Numerical simulation has been proven as a good tool and cost effective way for pre-molding analysis. Therefore, this research focuses on the unsteady three-dimensional (3D) simulation of mold filling during the thermoplastic injection molding process using ANSYS FLUENT 14 software. Common Polypropylene (PP) and medical grade materials are considered in the study. Commercial single screw injection molding machine (Battenfeld TM750/21 O) is used to study the flow front advancement of the common polypropylene at different injection pressures and melt temperatures ofa single cavity of the tray. GOTfFERT Rheograpb25 Capillary Rheometer machine is employed to perform the experiments on the rheological behavior of the polypropylene (i.e., shear rate and viscosity) at different melt temperatures. The rheological results are compared with those obtained by numerical simulation.
- PublicationPredicting Smoke Emission From Palm Oil Mill Using Artificial Neural Networks(2002-11)Ahmad Razlan Bin YusoffMalaysia produces 50 % of the total quantity of palm oil produced in the world and this makes it the largest palm oil producer in the world. Palm oil is produced in palm oil mills, which have their captive steam power plants and these plants use palm oil waste (shell and fibre) as fuel for the boilers. Unfortunately, the combustion products of these materials cause severe atmospheric pollutions. According to a survey in 1999, only 76 % of the palm oil mills in Malaysia meet the regulation of Department of Environment (DOE) regarding the emission. The emission released through the chimney can be monitored by modeling its process of input (in fuel, turbine, boiler) and output of the pollutants. Modeling the emission from the palm oil mill boiler based on Artificial Neural Networks (ANN) is used in this research.
- PublicationTar Removal From Biomass Producer Gas By Absorption And Adsorption Methods(2014-12)Ahmad, Nor AzlinaTar in biomass producer gas should be removed to avoid blocking of the pipe lines and to allow producer gas utilization in internal combustion engines (ICE) and turbines for power generation. Among the physical tar removal methods, scrubbing technique are more attractive to remove tar from biomass producer gas. This technique aims to use reusable material for tar removal. Tar removal system was conducted by two methods: absorption method (collected waste palm cooking oil (CWPCO), laboratory waste palm cooking oil (LWPCO), diesel oil and water) and combination of absorption method (optimum absorption medium are selected) with adsorption method (commercial activated carbon (CAC), empty fruit bunch char (EFBC) and oil palm shell char (OPSCĀ». Tar species and oil-based mediums (CWPCO, LWPCO and diesel oil) were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Whilst, adsorption medium properties were determined using Thermogravimetric Analyzer (TGA), Microstructure Analysis (BEn and Scanning Electron Microscope (SEM).
- PublicationThe Hp-Adaptive Finite Element Method For Three Dimensional Multiphysics(2014-03)Kamaludin, Siti SarahAlthough the hp-adaptive strategy is well implemented in two dimensional problems, its convergence performance in three-dimensional multiphysics problems particularly with tetrahedral mesh is still yet to be fully matured. This thesis presents a code development of a fully automatic hp-adaptive finite element method for steady-state multi physics problems in three dimensions. The adaptivity is achieved by a systematic combination of mesh refinements using bisecting approach(/Z) and polynomial order(p) extensions of the approximation functions. Mesh adaptation process is implemented such that conformity among the elements is preserved. The adaptive strategy is driven by a residual-based a posteriori error estimator computed element-wise, where a scheme has been developed to identify elements that need to undergo refinement processes.
- PublicationVibration attenuation of the small scale boat engine handle using dynamic vibration absorber(2022-01-01)Md Isa, Mohamad SyazwanA small-type motorboat engine used by fisherman in the rural area has a direct handle-engine mounting mechanism which can exposed them to the high level of vibration and lead to the Hand-arm Vibration syndrome (HAVs). This study investigates the vibration transmissibility of 3.3 Hp motorboat engine and the application of Dynamic Vibration Absorbers (DVA) at two critical points of motorboat handle to attenuate the vibration in specific direction and frequency ranges. A lab-scale experimental rig is constructed to represent the actual operation of the motorboat engine. Natural frequencies of the handle are determined before and after the DVA implementation to study the resonance effect that may excites the handle vibration.Two types of parameters are taken into consideration for the vibration measurement which is the engine speed (Speed 1: 3000 rpm and Speed 2: 6000 rpm) and gear condition (neutral gear and forward gear) in all three axis directions. From this study, the first and second natural frequencies of the handle are determined in the frequency ranges of 70-78 Hz and 92-95 Hz, respectively, and the values been shifted closed to the targeted frequency ranges when the DVAs are applied. From the vibration measurement, the handle resulted in high vibration at y axis direction within 45-50 Hz for Speed 1, and 95-100 Hz for Speed 2 in both neutral and forward gear conditions. Two set of DVAs are fabricated and attached at two critical points (point 1 and 3) for each relative engine speed. As a result, the DVAs are capable to reduce the handle vibration in y axis by 42.08% for neutral gear condition at Speed 1, while 53.56% of vibration reduction is obtained in y axis for Speed 2 at forward gear condition. The vibration transmissibility of the handle shows a significant result (above than 1) in frequency range of 0-100Hz and the application of DVAs have improved the vibration transmissibility of the handle. The vibration data is then filtered based on ISO 5349 and the result shows that by applying the DVA, the vibration transmissibility of the handle is significantly reduced by 57.14% for neutral gear condition at Speed 2 and 38.46% vibration reduction is achieved for forward gear condition at Speed 1. Thiscan subsequently reduce the risk of getting HAVs among the motorboat engine operators.