Pusat Pengajian Kejuruteraan Mekanikal - Tesis

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A Model For The Fuzzy Front End Of New Product Development Process
(2016-01)
Abd Rahman, Md Nizam
In 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.
A study of punch-die misalignment in square cup deep drawing process using experiment and finite element analysis
(2022-09-01)
Abdul Ghafar, Alimi
Square deep drawing is a forming process that transforms a flat sheet metal to a seamless vessel by using a set of punch and die. Any misalignment in the punch -die assembly during the process can cause thinning, which can result in the tearing of the drawn part. The onset of thinning due to punch-die misalignment is yet to be explored fully, thus understanding the thinning initiation will be useful for process optimization. In this study, a series of comprehensive methods to identify the presence of punch-die misalignment in square cup deep drawing process is implemented. These methods are deployed at the pre-drawing, during the drawing process and at the post drawing stage. In the pre-drawing stage, an image processing technique is utilized forpre-drawiing inspection. The captured images are analysed to identify the severity of misalignment between the punch and the die. At the second stage (during forming), an in-situ method is used to observe the presence of punch-die misalignment. For this purpose, a customised die rig is fabricated and installed on a universal tensile machine (UTM). A Commercial Electrolytic Zinc-Coated Steel Sheet (SECC) was used as the specimen for the deep drawing process, and the effect of misalignment severity on drawing force and wall thickness distribution are investigated. For comparison, a finite element (FE) simulation is utilized as an early prediction of the punch-die misalignment. The simulation was conducted using Abaqus/Explicit FEA software, utilitising the Hill’48 model, to determine the stress-strain diagram and forming limit diagram (FLD) of the SECC material. Two conditions of misalignment were simulated, 1) single axis punch-die misalignment and 2) multi axes punch-die misalignment with the misalignment severity of 0.1 mm to 0.5 mm. At the post-drawing stage, the wall thickness distributions of the cup for each misalignment conditions were investigated. Variations in wall thickness distributions would indicate the severity of misalignment between the punch and die. Specifically, a novel methods are introduced for detecting the presence of punch-die misalignment in square cup deep drawing process. Both the FE and experimental results were in good agreement with regard to the drawing forces and thinning patterns due to punch-die misalignment. Greater misalignment severity was observed to increase the drawing force and thinning in the wall of the drawn cup. For both misalignment conditions, similar wall thickness distribution patterns were observed, with the maximum thinning occurring in the cup sidewall and minimal thinning at the bottom of the cup. For single axis misalignment, the maximum thickening up to 18% has occured at the lowest misalignment severity of 0.1 mm. On the other hand, for misalignment severity of 0.3 mm and above, the maximum thinning in the x-axis was higher as compared to the y-axis by average of 0.53% and 1.72% based on FE and experimental results, respectively. For multi axes misalignment, the maximum thickening averages at 15%, while the thinning was more pronounced in the rolling direction as compared to the transverse direction. As a conclusion, this study had contribute a positive signification implication in die making, especially punch-die alignment issue in deep drawing process. Alignment punch-die is essential in square cup deep drawing process. A series of comprehensive approach for identifying punch-die misalignment issue according to this study can be referred by researcher and industrial practioner in making high quality square cup deep drawn product.
A study on low temperature synthesis of silicon carbide thermionic cathode and its electron emission analysis for thermionic energy converter
(2020-07-01)
Leong, Thye Jien
Energy conversion of renewable and clean energy such as thermal energy is often related to solar cell and photovoltaic cell. These are the rising technology devices that generate electrical energy for the use in industrial and residential sectors. In order to seek for an alternative approach in meeting the growing energy demand and reducing the dependency on conventional energy resources such as biomass energy, another direct thermal energy to electricity conversion device namely Thermionic Energy Converter (TEC) is being studied. However, the technology involved in this device has one major limitation which is the unavailability of low cost cathode materials with low work function yet easily-obtained. This drawback has motivated the study of cathode material in term of lowering the work function by surface nanostructuring the thermionic cathode for TEC in the mentioned research direction. By using atmospheric pressure chemical vapor deposition (APCVD) method, a low temperature (600°C) synthesis thermionic cathode was developed, as validated by the literature (Xi et al., 2006). In this approach, silicon carbide (SiC) nanostructures were synthesized on the silicon substrate. This method was optimized based on two parameters which are controlling the thickness of catalyst (Magnesium) and the amount of precursors (silicon tetrachloride and 2-ethoxyethanol) used in the experiments. Some material characterization techniques, such as SEM, EDX, and FESEM were performed to the thermionic cathode to support the proposed synthesis method. Besides, a new in-house built TEC system that is equipped with a vacuum chamber, CO2 laser heating system, turbomolecular pump, and digital nanoammeter was developed, which can manipulate temperature of the thermionic cathode. The electron emission analysis of thermionic cathode was performed at different temperature ranges where a copper plate (4.7eV) was used as the anode. Based on the results, a total reduction of ~0.36 eV to the work function of the p-type silicon (111) with ~4.84 eV is achieved by the as-synthesized SiC nanowires thermionic cathode using M200SC3 - ~4.48 eV sample. Lastly, the Schottky effect is proven showing an enhancement to the current density of the SiC nanowires thermionic cathode by compromising a small deviation of the work function of ~0.02 eV. These findings prove that the presence of SiC nanostructures on the thermionic cathode has achieved higher current density, 87 nA cm-2 with the presence of applied voltage at 4000 V/cm and 71.8 nA cm-2 at zero field effect, as compared to 14.4 nA cm-2 for the control sample in this TEC study.
Analysis Of Piston Secondary Motion
(2014-04)
April 2014
In an internal combustion engme, the piston performs secondary motion besides the primary reciprocating motion. The clearance between the piston skirt and cylinder liner allows the piston to move in the lateral direction and rotational motion about the piston pin axis. The piston secondary motion created impact between the piston skirt and the cylinder liner that radiates unwanted engine noise and increases friction loss. A measurement system consists of three laser displacements sensors are developed to capture the instantaneous piston motion and posture directly from the piston assembly under motorized condition. The laser spots aimed at the piston crown with machined profile in order to obtain the rotational and lateral motion of the piston. The instantaneous piston motion showed that the likelihood of contact between the piston skirt and the cylinder liner increases with the occurrence of the piston secondary motion. In addition, a non-linear model of the piston with reciprocating, lateral and rotational degree of freedom is developed to investigate the piston secondary motion and the piston slap induced vibration behavior of the single cylinder engine.
Analysis of void formation for no-flow underfill process using numerical simulation and machine learning-based methods
(2022-09-01)
Nashrudin, Muhammad Naqib
The no-flow underfill process has been developed as an alternative to the conventional capillary flow underfill. It offers low cost and lead time production effectively due to the integration of simultaneous reflow of solder interconnect and cure of underfill material. Somehow, no-flow underfill also faces the same reliability issue which is the potential void formation during the process. The research on the void formation issue in no-flow underfill has been found scarce. In addition, the research works on no-flow underfill focused on the experimental method which is costly and very limited to study the root cause of the issue. Therefore, this research presents a numerical simulation study of the no-flow underfill which has the ability to track dynamically the movement of the flow of underfill in real time during the process. This research investigates and predicts the possible void formation of no-flow underfill. Three major parameters were selected to align with industry requirements which are chip placement speed, bump pitches and viscosity of underfill. Subsequently, previous literature of no-flow underfill experiment, industrial no-flow underfill experiment and current scaled-up imitated flip-chip experiment were compared in term of flow and void formation percentage to validate with the current numerical simulation. Overall, the current numerical simulation produced low discrepancy which is less than 15% error among all the experiments and affirmed the capability and accuracy of the numerical simulation model. It was found that the void formation rate increases with the chip placement speed but decreases with the increase in bump pitch. The highest chip placement speed of 14 mm/s produces 4-6% meanwhile, the low chip placement speed (2-5 mm/s) produces around 2-3.5% of void formation. Moreover, several supervised machine learning prediction-based methods such as linear regression, decision forest regression and neural network regression were implemented to train the numerical values and to investigate further the most significant parameter that affects the void formation in the chip. It is observed that linear regression, decision forest regression and neural network regression produced mean absolute errors between 0.1588, 0.176375, and 0.1818, respectively. The neural network regression is the preferred algorithm method of machine learning in the study since it shows the least error with a high R2 value of 0.95159. Based on permutation feature importance, the most significant parameter that affect the formation of void in the no-flow underfill was chip placement speed compared to bump pitches and underfill’s viscosity with a score of 1.7916, 0.2962 and 0.000878, respectively. This research provided engineers in the microelectronic industry with a deep understanding of the void formation and expected to provide an appropriate guide to minimize the failure for the development of no-flow underfill in the future.
Attenuation of humming type noise and vibration in vehicle hvac system using a tuneable dynamic vibration absorber
(2023-06-01)
Muhammad Safwan Bin Abdul Aziz
The purpose of this research is to study the effect of a Tuneable Dynamic Vibration Absorber (TDVA) in reducing the humming type noise and vibration that originating from the Heating, Ventilation and Air Conditioning (HVAC) system of a Proton Exora vehicle. In this study, a lab-scale experimental rig of Proton Exora HVAC system was built to represent the system inside the vehicle. On top of that, the study also been conducted on the Proton Exora vehicle itself for the data comparison. The TDVA was designed and tuned according to the natural frequencies of the Air Conditioning (AC) pipe structure obtained from Experimental Modal Analysis (EMA) of both the system and vehicle level with natural frequency values of 148 Hz and 173 Hz respectively. Two TDVA, with the length of 5.53 cm and 4.98 cm were fabricated and applied at both lab scale test rig and vehicle level, respectively. The humming type noise and vibration characteristics of the HVAC components were recorded and compared, with and without the implementation of TDVA. The implementation of TDVA into the system was found to reduce the vibration level of the AC Pipe by 80 % and subsequently reducing the noise and vibration level of the whole HVAC system inside the cabin area by 1.5 dBA. It also been observed that the applied TDVA has an effective frequency range of 100 – 500 Hz for the vehicle level and 75 – 250 Hz for the lab scale test rig.
Bio-based and hybrid based polymer composites for enclosures of memory storage device application
(2022-08-01)
Janakiraman, Vishnu Chandar
A large proportion of consumer electrical and electronic packaging applications were made up of thermoplastics. Casings or enclosures are generally used in circuit boards, and data storage which is made up of plastic to ensure the appliances are mobile, lightweight while being tough and durable and at the same time, the plastics used in these applications are very high and also not biodegradable. This research aims to reduce the usage of plastics in storage applications via two approaches, i.e., bio-based and hybrid-based polymer composites. In this work, pure polymer [polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), cellulose acetate (CA)] and its bio-based composite ((PLA/Aluminium oxide (Al2O3)/Boron Nitride (BN)), PLA/BN/Graphene tubes (GT), PHBV/Al2O3/BN, PHBV/BN/GT, CA/Al2O3/BN, CA/BN/GT) sheets with different concentration of hybrid filler [(Aluminium oxide (Al2O3)/Boron nitride (BN), BN/Graphene tubes (GT)] were fabricated. Similarly, pure thermoplastics (polyoxymethylene (POM), polypropylene(PP), polycarbonate (PC)) and its hybrid-based composite POM/PHBV/Al2O3/BN, POM/PHBV/BN/GT, PP/cellulose fiber (CF)/Al2O3/BN, PP/CF/BN/GT, PC/basalt fiber (BF)/Al2O3/BN, PC/BF/BN/GT) sheets with different concentration of hybrid fillers were fabricated using internal mixer equipment and compression molding method. The effect of fillers on the structural, optical, thermal, thermophysical, mechanical, surface, electrical properties of the pure polymer and its bio-based and hybrid-based polymer composite sheets were studied, compared, and suggested for electronic packaging applications. XRD results confirm the presence of polymers and fillers (ceramic, carbon, and natural) in the prepared bio-based and hybrid-based composites. The prepared bio-based (PLA/BN/GT, PHBV/BN/GT, CA/BN/GT) and hybrid-based (POM/PHBV/BN/GT, PP/CF/BN/GT, PC/BF/BN/GT) polymer composites exhibit high UV-VIS-NIR absorption, thermal conductivity (0.29 - 0.51 W/mK and 0.35 – 0.53 W/mK), flexural strength (34.2 – 66.4 MPa and 59.1 –74.8 MPa), flexural modulus (1088 – 3239 MPa and 1313 – 3424 MPa), storage modulus (726 – 2130 MPa and 1492 – 3132 MPa), scratch hardness (0.43 – 0.73 GPa and 0.44 – 1.19 GPa), and low CTE (17 - 42.9 µm/m ºC and 38.6 – 114 µm/m ºC), ESD (<10V to <100V and <10V) compared to composites with Al2O3/BN filler and pure polymer that may be due to the high thermal conductivity, mechanical strength and synergetic effect of BN and GT filler. As for dielectric permittivity, Al2O3/BN reinforced composites exhibit favourable dielectric constant (3.02 - 4.74 and 2.72 –3.37) and loss (< 0.02), whereas BN/GT reinforced polymer composites shows higher values at a lower frequency. Like bio-based, hybrid-based polymer composites also follows the same trend in dielectric permittivity. On comparing the bio-based composites, CA/BN/GT polymer composites are suitable for USB products with high storage capacity as per the obtained melting, glass transition temperature, CTE, ESD, mechanical, and scratch performance, whereas PLA/BN/GT and PHBV/BN/GT polymer composites are suitable for USB products with very low storage capacity and can ultimately reduce 98% of plastics. Similarly, the prepared hybrid-based polymer composites (POM/PHBV, PP/CF, PC/BF) with BN/GT filler are suitable for USB, SSD, and HDD products with both low and high capacity as per the obtained thermal, ESD, mechanical, and scratch performance and can ultimately reduce 15-40% of plastics in enclosure applications.
Cascaded cylindrical micro-perforated panel for noise broadband attenuation
(2023-04-01)
Mohamad Izudin Bin Alisah
This research presents an analysis of cascaded cylindrical micro-perforated panel (MPP) for absorbing the sound of a flow system in a circular duct application. This is important for the cases where the noise source comes from multi direction as actual application would not in single direction. Since the typical MPP has limited narrow band attenuation, it is necessary to have a specific MPP to radiate noise from circular direction and broadband attenuation. The aim of this study is to model using simplified transfer matrix method, optimized via genetic algorithm and demonstrate the effectiveness of cascaded cylindrical micro-perforated panel on vacuum cleaner. Cascaded cylindrical MPP is a special class of cylindrical MPP, where two cylindrical MPPs are arranged in series to improve sound attenuation. The manufacturing of MPP primarily involves the machining of micro perforations because the small holes are not readily made using injection moulding due to the complexity of the die, flow control of the molten polymer through the small orifices and dimensional stability, making it unsuitable for mass production. This limitation can be overcome with the use of additive manufacturing (AM) technology based fused deposition method (FDM), where the micro perforations can be designed and manufactured, with relatively larger tolerances. Moreover, parametric studies on basis of perforation diameter, perforation ratio, depth of air cavity on the diameter of the duct and length ratio are carried out. Result shows that the transmission loss performance of cascaded cylindrical MPP can be improved by reducing the perforation diameter and by correct selection of perforation ratio and air cavity depth value. Experimental validation ensures that the manufactured cascaded cylindrical MPP is performed according to design. The application of transfer TMM framework was aligned with similar trend with boundary element method (BEM) and measured result via two-load method measurement. Small shift of the transmission loss peak values attributed to perforations in printed structures that were not perfectly circular in shape. The average Root Mean Square Error (RMSE) obtained was 3.04 dB. A case study is demonstrated here in the design and additive manufacturing of cascaded cylindrical MPP to attenuate peak noise at 1650 Hz. The manufactured cascaded cylindrical MPP is installed on a vacuum cleaner duct, and the measurement of sound power level shows a reduction of 5.2 dB (A).
Combustion characterization and optimization of mixture biomass producer gas and methane in a constant volume combustion chamber system for fuel combustion efficiency enchancement
(2023-03-01)
Teh Jun Sheng
Most of the world’s energy requirements are still derived from natural resources. This will result in a catastrophic energy crisis with negative environmental consequences. The increased energy supply will result in greater consumption of non-renewable sources. The production of biomass producer gas (BPG) from biomass gasification has received significant attention for reducing global emissions as an alternative fuel because of the depletion of non-renewable resources. The properties of biomass feedstocks significantly influence combustion characteristics. The objective of this experimental study was to determine the combustion characteristics: flame propagation speed, chamber pressure trace and emissions of BPG at different equivalence ratio to obtain the lower chamber peak pressure and greenhouse gas emissions. Using the direct visualization technique, an optical constant volume combustion chamber (CVCC) was developed to measure combustion characteristics. Liquid petroleum gas (LPG) was used to compare chamber pressure and flame propagation speed in the CVCC calibration. In comparison to wood pellet (WP), coconut husk (CH), and palm kernel shell (PKS), the chamber peak pressure at 𝜙 equal to 1 of CH for the combustion of BPG is the lowest at 20.84 bar. At 𝜙 of 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and 1.3, the chamber peak pressure of CH was discovered to be around 17.77, 18.12, 18.81, 20.84, 20.39, 17.25, and 16.37 bar. Compared to the other two types of BPG, CH produces the lowest emission of CO2 and CO, at 2.03% and 0.02%, respectively. From the literature review, increasing CH4 content in the fuel can increase the mole fraction of H, O2, and OH radicals and reaction rates in the flame, further accelerating the flame of the mixtures. Therefore, an optimization study is needed to determine the higher performance combustion of BPG with an increase in the composition of methane. The combustion experiment study was optimized with 17 designed experiments, 0.9 to 1.1 equivalence ratio, and the 0 to 0.1 mole fraction of methane fuel. The BPG-methane-air mixture, according to optimization analysis, achieves the fastest flame propagation speed and the lower chamber peak pressure at 𝜙 equal to 1 and a mole fraction of methane fuel of 0.083. Compared to the BPG-air mixture (𝜙 equal to 1), which had a chamber peak pressure of 20.84 bar, the average results of the optimum configuration parameters reveal a lower peak pressure was 18.97 bar. Comparison of the chamber peak pressure between BPG-methane-air mixture and BPG-air mixture varied by approximately 9.39%. In this context, the gross heat release rate (HRR) is observed to be around 94.44 kW, which represents a 20% reduction when compared to CH fuel. However, there is a slight increase in the emissions of CO and CO2, with a rise of 0.01% and 5%, respectively. In conclusion, the optimal mixture of BPG and methane fuel provides the optimum flame propagation speed with lower chamber peak pressure than BPG.
Data mining for service industry: branch classification of a malaysia retail bank
(2023-01-01)
Chong Siu Hou
The on-going customers’ behavioural shifts from assessing physical banking services to virtual banking services have made retail banks continually review their physical banking network strategies. Such exercise allows the retail banks to maintain their competitive advantages over their competitors while balancing their business portfolios between online banking service needs, optimizing physical clientele coverage, and minimizing costs in running a physical branch network. The research objective is to develop a suitable classification model in decision-making that can mimic experts’ opinions on retail bank branch operational status using a case study on a Malaysian retail bank. Seventy-four branch attributes were used to build a classification model in which experts’ opinions are included as an attribute to allow the data mining (DM) application to emulate experts’ decision-making. The research methodology involves collecting the experts’ opinion through an expert survey to determine the feasibility of a branch remaining open or closing permanently as part of the bank’s network rationalization strategy. The value obtained from the survey was converted into a variable termed “aggregate closure possibility” in this study and then discretized into target class datasets. Then ten classification models were constructed, including ZeroR, Decision Tree, Random Forest, Naïve Bayes etc. Next, three experiments were conducted. The first experiment examined the effect of hyperparameter tuning on classification accuracy. The second experiment studied the impact of changes in the number of target classes on classifier accuracy and then highlighted the best-performing classifier. When the number of target classes was optimized, the accuracy of classifiers improved drastically, of which, three classifiers (Decision Table, J48, and JRip) were the most accurate classifiers. The third experiment studied the effect of attribute selection and instance reduction in optimizing classification performance. It was observed that the accuracy of most classifiers improved proportionate to the reduction of numbers of attributes and instances where Decision Table, J48, BayesNet, and JRip were the best performing classifiers in the third experiment. The result shows that JRip was the best performing classifier in all three experiments. Attribute selection and instance reduction optimized the classification accuracy in encompassing efficient datasets. The study also showed that the DM application could emulate expert opinion in decision-making in retail banking sector. In conclusion, the study has successfully achieved its research objectives. The study contributes to research knowledge on how DM capabilities could improve management decision-making in a real-world application.
Design and implementation of six rotors unmanned aerial vehicle
(2010-04-01)
Mohamed Aziyen, Mohamed Afique
The control of a helicopter is complex, and includes the interaction of forces and the balancing of them. Although a stable condition can be achieved with sophisticated control system, good mechanical design can reduce the problem of instability of a helicopter. One of the designs is the coaxial types of blade system. Nevertheless, a good control system is still needed since a helicopter control involves many parameters. PIC16F876A microcontroller has been used to measured the input from sensor, do the calculation and control the actuators). In this project, ultrasonic sensor is used to control the height of the helicopter. The force that been produce by the helicopter must be the same to make sure that the helicopter is stable.
Development and documentation on use of completely randomised design
(2010-04-01)
Hamid, Zulkharnain
This project presents the development and documentation of actual engineering examples on the use of the Completely Randomized Design (CRD) in PPKEE. The examples involve a single factor experiment that uses the analysis of variance (ANOVA) technique to analyze the data. Basically the project is to understand the single factor analysis on use of the Completely Randomised Design. The other objective of this project are to search the actual use completely Randomized Design final year students of EE School. After searching, the actual examples of potential use of the Completely Randomised Design are developed based on type of research conducted by the EE students. Minitab is using to analysis the data from the previous final year report. There are a two phase in this project are literature review and develop the examples. The parts reviews and searching of the examples involve the three major courses in school of electrical engineering which is Electrical, Electronic and Mechatronic engineering. From the review of the previous final year report, three examples are developed in the project. The evaluation form was designed to get a feedback from engineering student regarding the examples that have been given. From the analysis of the evaluation form, the performance of the examples were developed are at a good level.
Development and performance analysis of hydraulic hybrid regenerative braking system for passenger vehicle
(2022-01-01)
Idris, Khairul Anuar
The 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 pump’s 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.
Development of finger-based computer mouse by using wiimote
(2009-04-01)
Lee, Wee Chuen
This report presents the project of finger-based computer mouse by using a game controller of Nintendo Wii, Wiimote. This project is focusing on developing an alternative computer mouse which is cost-effective, real-time application, user-friendly and can be used at a further distance from computer. It consists of a hardware setup for sending infrared (IR) light to Wiimote and a Graphical User Interface (GUI) that is built by using Microsoft Visual C++. A C++ library, “WiiYourself!”, is being used to obtain three IR dots’ coordinates from Wiimote, which are implemented for computer mouse’s functions. From the experiment, it is found that the user can successfully move the mouse pointer and perform clicking at a maximum distance about 2 meters away from Wiimote, which is good for presentation. The main drawback is the batteries of the glove with IR LED need to be changed after four hours of usage as its voltage dropped to a level that would worsen its performance. Besides, as the user used this system for long time, the users hand started to be uncomfortable. At this moment, the user can successfully move and perform clicking just like a conventional computer mouse with some limitations.
Discrete phase model simulation and optimization of different types nano-reinforced solder fillet using taguchi analysis and neural network method
(2021-12-01)
Muhamed Mukhtar, Muhamed Abdul Fatah
Recently, the electronic industry required electronic components to become reliable, lightweight, and miniature. In order to ensure the functionality of electronic devices, advanced joining through the nano-reinforced solder material was required. In previous studies, the addition of different types of nanoparticles to lead-free solders has been studied. One of the strengthened elements added, such as NiO and TiO2, helps the solder fillet to have better mechanical properties. Nevertheless, there is still a large research gap in the miniaturized part assembly processes through nano-reinforced solder paste on the actual surface mount devices. Hence, this research aims to investigate the advanced joining of ultra-fine packages using the nano-reinforced solder paste. Nanoparticles material name, TiO2, Fe2O3, and NiO with (0.01wt. %, 0.05 wt. %, and 0.15 wt. %) were selected to be reinforced with lead-free solder paste (SAC 305 type 5) to form three different types of nanoparticles samples. The nano-reinforced solder paste was contrasted with the pure SAC305 solder paste in terms of material and mechanical properties. In the current analysis, a two-way interaction is implemented using both the fluid volume method (VOF) and the disperse phase method (DPM) to account for the interaction between both the nanoparticles and the molten solder. DPM simulation is capable of viewing the comprehensive trajectory of nanoparticles as it undergoes thermal reflow from SAC305 based on the comparison of the simulation the experimental result. Additionally, for all cases of nanoparticles being used, strong agreement can be seen between both experimental and simulation data collected. By using different experimental techniques, the microstructure, fillet height, hardness and Modulus Young were investigated. The experimental results showed that the presence of nanoparticles generally strengthened the ultra-fine solder joint's material and mechanical properties. The reflow soldering process parameters were optimized by Taguchi technique based on Taguchi’s L16 orthogonal array. The optimum weighted percentage and nanoparticle material types were determined, and their percentage of contribution was estimated by applying the signal-to-noise ratio and analysis of variance. By adding 0.15 wt. % of TiO2, Fe2O3, and NiO, respectively, it increased the hardness and shear strength of the solder joint. The optimal configuration and the highest mean value of hardness and the modulus Young were obtained by 0.15 wt. % of SAC305+TiO2 nanoparticles were0.2875GPa and 89.65GPa. Meanwhile, optimal configuration and the highest mean for fillet height were obtained by 0.05 wt. % of SAC305+NiO nanoparticles was 0.1719mm. Quasi Newton method of Neural Network (NN) was used to train the experimental values. In comparison between experimental and neural network model results, the percentage error of predictive models for fillet height, hardness, and modulus Young were -0.046% , 1.077% ,and 20.420 %. This research provides engineers with a deep understanding of the ultra-fine package features of the nano-reinforced solder joint in the microelectronics industry. The results are expected to provide an appropriate guide and reference for the electronics industries in order to develop nano-reinforced solder joints of miniaturized electronic packages in the future.
Effect of aperture filling parameters of solder paste on stencil printing process
(2020-05-01)
Rusdi, Mohd Syakirin
The stage that causes major concern compared to the other stages in Surface Mount Technology (SMT) is known as the stencil printing stage. The study of pre-stencil printing is performed using simulation software to minimize fabrication costs and time. Therefore, this research focuses on the 3D simulation of aperture filling using lead-free solder during the stencil printing process via the usage of CFD simulation. The aperture filling of a solder paste at a varying squeegee pressure, squeegee speed and separation speed were studied using a commercial solder paste printer (DEK 265), and a 3D solder paste scanner (KOH YOUNG Aspire 2). A PCB that measures at 183 mm × 133 mm with 2 mm thickness was used in the experiment. Optimization of the process was done via Response Surface Methodology (RSM) where optimum solder filling volume, solder paste height and solder area coverage were obtained during the printing process. The optimum values suggested by RSM were squeegee pressure = 0.69 MPa, squeegee speed = 35 mm/s, and separation speed = 0.498 mm/s, and the optimal responses were volume = 0.783 mm3, height = 0.121 mm, and area = 6.481 mm2. The optimized parameters then were used as the validating data to carry out other extending studies. Anton Parr Physica MCR 301 Rotary Rheometer machine was used to conduct experiments on solder paste rheology (shear rate and viscosity). Parallel-plate (PP) and Cone-plate (CP) spindle were used to carry out five different tests consisting of different spindle type and setting. The volume filled under different squeegee speeds found that PP of 0.5mm gap exhibited the lowest average discrepancy value at 5.4% while CP1° and PP 0.5mm at 11.6% for different aperture sizes. The average discrepancy was the comparison between experiments and simulations results. Then, the studies were further extended to simulate the stencil printing process by using ANSYS Fluent 19. VOF method with Cross viscosity model was selected to undergo the numerical simulation. The volume filled by the solder paste at different aperture size according to the experiment and simulation results were compared. For different aperture size, all the results showed a similar trend with an average discrepancy of 11.6%. Furthermore, another study was added to investigate the stencil printing process efficiency at different squeegee speed and aperture size. The performance of the solder pastes for stencil printing is then compared with different lead-free solder paste (SAC105, SAC307, SAC305, SAC405 and SN100C). Leaded solder paste (Sn62Pb36Ag2) was also included in the analysis to demonstrate how well the lead-free solder pastes perform in comparison to the leaded solder paste. The research results were analyzed by comparing the effects of different angles, stencil thickness and aperture size. Results showed that the SAC305 gives the best result compared to other lead-free solder pastes and also leaded solder paste.
Effect of cold deformation on properties of aluminium alloy fabricated using wire arc additive manufacturing technique
(2023-04-01)
Muhammad Ajwad Bin Roslee
Additive manufacturing (AM) owns a huge potential in repair and remanufacturing industries due to its advantage of minimizing waste while having the abilities to produce complex shapes without mold. Current technique to obtain net shape is limited due to strength and lead time issues. AM also provides low cost solution for repairs with wire arc additive manufacturing (WAAM) which use common welding technique. However, this method produces parts with lower strength and hardness due to the high heat input and porosity. In this study, WAAM produced parts was constructed using manual TIG welding at different orientation and welding direction and new strategy was proposed, where cold forging process is introduced as a post deposition treatment, where the parts are subjected to different thickness reduction. The main aim of this study is to evaluate the tensile properties and hardness of forged AA4043 wire arc additive manufacturing (WAAM) constructed at different welding orientation and direction. Result discovered that the ultimate tensile strength (UTS) increased by 44%, from average UTS of 160 MPa to 200 MPa, and hardness value increases by 70%, from average hardness of 43 HV to 73 HV. Using SEM analysis, it is discovered that forging reduced the porosity sizes by 90%. Even with the improvement made by forging, upright orientation still suffer from interlayer strength, producing lower UTS compared to other parameters. Keywords: WAAM; AA4043; strain hardening; cold forging; repair
Effect of cold deformation on tribological performance of additive manufactured aluminum alloy er 5356
(2023-09-01)
Muhammad Faris Akmal Bin Md. Azlin
As a result of severe sliding wear, the automotive parts are often sent to landfills instead of being repaired or remanufactured. Metal additive manufacturing is now an alternative for reconstructing the damaged section. Despite that, the properties of the part may be affected due to heat during welding. Post-weld deformation, like cold deformation, is known as one of the property enhancement methods used to retain mechanical properties. The effect of cold deformation on the wear performance of aluminum alloy ER 5356 was investigated in this study using MIG-based wire arc additive manufacturing (WAAM). The cold forging process was conducted at room temperature and deformed using a 100-ton mechanical press machine. Unforged and forged specimens were compared to obtain specific wear rates for dry and wet sliding. It was observed that forged specimens have a lower specific wear rate than unforged specimens for both dry and wet cases at various speeds with applied loads. The range of the specific wear rate (mm3/Nm) for unforged specimens for dry sliding was 4.25 x 10-5 to 6.29 x 10-5 mm3/Nm, while for wet sliding, the specific wear rate ranges between 8.91 x 10-6 and 1.41 x 10-5 mm3/Nm. On the other hand, for forged specimens, the ranges of the specific wear rate in dry and wet sliding cases were 2.89 x 10-5 to 5.28 x 10-5mm3/Nm and 2.07 x 10-6 to 4.68 x 10-5 mm3/Nm, respectively. The coefficient of friction (COF) for unforged and forged specimens in dry sliding for all speeds and applied loads decreases as the specific wear rate increases. However, COF for wet sliding is lower for both unforged and forged samples. The cold forging process provides a lower specific wear rate and COF for wet and dry cases compared to unforged samples. Based on this study, cold forging shows a good and potential alternative to reverse the properties such as the tribological performance for part repair or remanufacturing.
Effect of fuel injection strategies and intake air supply control on performance, exhaust emission, and combustion characteristics of diesel engine fuelled with biodiesel fuel
(2023-06-01)
Leong Hau
Split injection strategies were generally agreed to be a promising strategy to achieve simultaneous nitrous oxide (NOx) and soot reduction. The air intake channel of a commercial diesel engine is designed for maximum airflow rate under severe load conditions. At medium load, excessive airflow may contribute to NOx formation. Therefore, air intake restriction with exhaust gas recirculation (EGR) might be a viable option to couple with a split injection scheme when the engine operates in part load. The study comprises of three parts. Firstly, an engine test rig has been built, which consists of a dynamometer, exhaust gas analyser, and an engine coupled with an in-house built electronic fuel injection control unit (ECU). Secondly, the effect of biodiesel blend on engine performance and emission has been studied, and the most desired fuel blend and engine operating condition was used in the next step. Thirdly, the effect of the double and triple split injection with different timing and injection ratio coupled with EGR and intake air throttling has been studied. It has been found that B60 POME blend at 2000rpm and 80 Nm were the optimize mid load engine condition. Where 5050 double split injection with 12CA was the optimize split injection strategies. Intake air throttling has been found to enhance EGR's beneficial impact by driving more exhaust gas via the EGR path. A response surface methodology (RSM) study was performed to optimise air control and split fuel injection strategies to maximise engine performance and minimise exhaust emissions The optimum parameter appears at 12 °CA dwell angle, -4°ATDC SOI timing, 40% intake throttle opening, 6.75% EGR, 800 bar fuel injection pressure, and 50% split injection ratio.
Effect of sintering temperature on the properties of magnesium substituted biphasic calcium phosphate
(2020-05-01)
Marahat, Muhammad Hanif
Biphasic calcium phosphate (BCP) is a bioceramic material which are known to have two distinguish phases which is hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). The aim of this research is to improve the limitation in mechanical properties of BCP by the addition of 0.025 wt% of Mg. The addition of Mg was able to increase the densification of BCP by stabilizing the β-TCP phase and delay the formation of α-TCP at high sintering temperature. Therefore, this study emphasizes on the effect of Mg substitution on BCP upon densification through sintering process. BCP and MgBCP powder was synthesized via wet precipitation method using the ratio of (Ca+Mg)/P 1.61. The obtained as-synthesized powder was pressed in pellet shape and sinter at temperature 900oC, 1000oC and 1100oC. The analysis is separated into two part which covers the unsintered as-synthesized powder and sintered pellet. The as-synthesized powder shows that Mg substitution improved the crystallinity peak from XRD analysis. For sintered pellet, the result for porosity of BCP have shown that the porosity of BCP have decreases from 40% at 900oC to 25% at 1100oC respectively. The trend also decreases as Mg was added, from 39% (900oC) to 22% (1100oC). Moreover, the result for mechanical testing shows that the MgBCP pellet is having higher mechanical strength compared to BCP pellet. The highest compressive strength for BCP pellet is at 5.02 MPa and MgBCP is at 9.41 MPa. The same trend with Vickers hardness testing which record BCP (0.82 GPa) and MgBCP (0.93 GPa). Overall trend shows that sintering at 1100oC gives better mechanical strength. Moreover, in term of biological analysis, MgBCP pellet gives more formation of apatite layer on its surface under FESEM observation due to more dissolution process for apatite to growth.

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