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- PublicationNumerical and experimental studies of a different striker bar shape for the achievement of a constant strain rate in shpb tests(2023-07-14)The Split Hopkinson Pressure Bar (SHPB) test is a widely used experimental technique for investigating the dynamic behaviour of materials under high strain rates. One of the challenges in conducting SHPB tests is achieving a constant strain rate throughout the duration of the test. Different strain rates often result in different stress-strain responses, which makes comparative material analysis difficult if the strain rate is not constant. The accuracy of the experiment result also can be disturbed when the strain rate is not constant. This research focuses on studying the effectiveness of a different striker bar shape in attaining a constant strain rate in SHPB experiments. The new striker bar design, which is conical in shape with a spherical end and tapered end surface, has been developed and compared with the conventional flat end striker bar. The striker bar used to impact the specimen which is copper to study the effect toward achieving constant strain rate in SHPB test. The copper was impacted with three different pressures for each striker bar design. In this study also, we develop a finite element model (FEM) for each striker bar design to study the wave propagation of different shape striker bar and to identify whether the wave produced in the SHPB test can be replicated. The results show that the new striker bar design has a significant impact on achieving a constant strain rate in this SHPB test. The new design effectively reduces the strain rate variations for certain pressure throughout the duration of the test compared to the conventional striker bar shape. The magnitude of the stress strain curve graph for the new striker design are different and much lower compared to the conventional striker bar design. The new striker bar design also has a lower strain rate value compared to the conventional flat end surface striker bar. In conclusion, different shapes of striker bars in SHPB tests have a huge impact on achieving constant strain rate. The simulation for new striker bar design have encounter an error due to several factor and cannot be used to determine the similarity of the experimental and simulation results.
- PublicationA single unit concept and design of a high maneuverability mobile robot(2023-07)The aim of his project is to develop a single unit concept and design of a high maneuverability mobile robot to assists human beings in hazardous tasks. Robots that can climb walls can complete work in unsafe places where people might find them risky or inaccessible. They are able to work in challenging environments like high altitudes, cramped quarters, or places where chemicals, radiation, or extremely hot or cold circumstances could pose a risk. The risk to human workers is greatly decreased by utilising a wall-climbing robot. The robot's ability to maneuver through a dangerous environment and carry out activities without putting people in danger reduces the likelihood of mishaps, injuries, or exposure to poisonous materials. This magnet embedded wall-climbing robot is able climb vertical surfaces like metal buildings, ceilings, or walls. This makes it possible for it to reach places that are difficult or hazardous for humans to access, such as heights. It offers human employees who would normally need to use ladders, scaffolding, or harnesses a safer alternative. Furthermore, the robot can firmly cling to surfaces thanks to the high magnetic force, which also ensures its attachment even in risky or unstable conditions. This stability reduces the possibility of the robot falling or slipping, which is essential when working in high or risky places. This design is able to solve the existing limitations of wall-climbing robot. A solid model drawing has been created using SolidWorks software and control system were done by using Arduino IDE software and Blynk app. Then, the prototype was fabricated using 3D printing and also cutting process. The hardware that have been used to connect the robot are NODEMCU ESP32 board, L298N motor driver and DC motors. After building the prototype the experimental studies and testing on the prototype were carried out. The final phase of the project was the application of the prototype on the real surface of the environment which is metal or iron board which acts as the wall. The robot was activated with the Wi-Fi. The prototype of the wall climbing robot was able to move in vertical direction of the wall with the magnetic adhesion from Neodymium magnet that has been attached with passive attachment.
- PublicationTetrahedral amorphous carbon (TaC-Ti) nanocomposite coating application on selector carrier for friction reduction in double diaphragm pump(2023-07-14)This study focuses on the application of a tetrahedral amorphous carbon (TaC Ti) nanocomposite coating on the selector carrier of a double diaphragm pump to reduce friction. The objective is to identify a suitable coating that can improve the lifespan of the carrier by introducing tribological properties. The research involves characterizing the coating's tribological properties, including the coefficient of friction (CoF) and wear resistance, through experimental testing and analysis. Furthermore, the mechanical properties of the coating, such as hardness and reduced modulus, are evaluated using nano-indentation techniques. At the end of this study, the coefficient of friction values for each coating were determined: uncoated (0.20), anodized coated (0.19), anodized with Teflon coated (0.16), and TaC-Ti (0.10). The results clearly indicate that TaC-Ti coating exhibits the lowest coefficient of friction among the tested coatings. This finding shows that TaC-Ti coating possesses superior tribological properties, making it a suitable choice or improving the lifespan of the carrier. By reducing friction and wear, the TaC-Ti coating can enhance the overall performance and durability of the carrier in practical applications. Additionally, the coating exhibits superior wear resistance and enhanced mechanical properties compared to other coatings. The findings from this study contribute valuable insights into the application of TaC-Ti nanocomposite coatings for friction reduction in double diaphragm pumps.
- PublicationExperimental study of temperature distribution on bias acoustic liner(2023-07-13)Aircraft icing can cause serious damage to aircraft, which can lead to crashes. There are number of ways to mitigate aircraft icing, including utilizing electrical thermal deicing to produce heat and melt the ice accumulated on aircraft. Furthermore, to mitigate the engine noise produced by aircraft, a noise abatement tool, Bias Acoustic Liner (BAL) is installed in the nacelle cowl zone, which is the primary source of noise. However, there is limited understanding of how the liner behaves thermally during operational conditions with the ice protection system. Therefore, this research paper aims to conduct an experimental testing and analyze the heat transfer rate of Bias Acoustic Liner (BAL) to facilitate with anti-icing system in aircraft applications. Ten averages of free stream velocities ranging between 0.6 m/s to 2.1 m/s, with ten different heat dissipations ranging from 0.1686 W to 2.6765 W have been examined. Reynolds number recorded in the experiment are ranging from 4800 to 15600. The respective temperature measurements and velocities for this experiment were recorded using thermocouples, data logger and anemometer, where the overall uncertainties for both systematic error and random error is 5.13 %. Based on the recorded data, it can be observed that the heat transfer coefficient decreases as the heat dissipation is higher. Hence, based on the experiment conducted, it can be indicated that increasing the temperature will lead to a decrease in the heat transfer coefficient. Besides, the heat transfer coefficient and Nusselt number exhibit a proportional relationship with the Reynolds number for all heat dissipation rates. In conclusion, the bias acoustic liner proves to be a highly effective tool for noise reduction and can work efficiently with ice protection system in aircraft.
- PublicationNumerical modelling and simulation for dynamic response and fatigue life prediction of printed circuit board(2023-07-06)In everyday life, PCB in electronics is receiving impact from various sources such as vibrational damage, fall damage, or thermal damage via abusive usage or act from users. Hence, designers and engineers should identify the durability and quality of their PCB design to ensure the electrical circuit of electronic gadgets provided by the solder ball connecting the PCB and BGA package mechanically will not fail easily via product reliability testing with reference to JEDEC standards. To reduce material wastage in the reliability testing stage, FEA simulation came up as a viable solution to this conflict. In this study, a simplified 3D geometrical PCBA model with accurate material data obtained from literature is simulated with controlled boundary conditions, which act as the cyclic fatigue loading sustained by the PCBA. Differing from the conventional mean, BLCBT is used rather than BLDT due to its better result reproducibility and accuracy. The simulated PCBA model is subjected to cyclic bending load with similar magnitude in both upward and downward directions discretely to identify the effect of loading conditions towards the plasticity damage sustained by the most critical solder ball. Besides, the PCBA is also subjected to low cycle fatigue loading (100 cycles) and higher cycle fatigue loading (500 cycles) to obtain the trend of plasticity damage sustained by the most critical solder ball. Finally, the equivalent plastic strain sustained by the solder ball from the simulation result is exported and the fatigue life of PCBA is calculated using Manson-Coffin fitted low cycle fatigue life numerical model for metal. The strain against the life curve of PCBA is predicted using the Manson-Coffin equation and post-processed using MATLAB.
Most viewed
- ItemMAT 122E- Differential Equations I (Persamaan Pembezaan I)(Universiti Sains Malaysia, 2006-06)Universiti Sains Malaysia Peperiksaan Kursus Semasa Cuti Panjang Sidang Akademik 2005/2006 Jun 2006 MAT 122E- Differential Equations I [Persamaan Pembezaan I] Duration : 3 hours [Masa : 3 jam]
- ItemFlow Pattern And Hydraulic Characteristics A Of Hexagonal Modular As Channel Bed(Universiti Sains Malaysia, 2019-05-01)Studies have shown that sustainable designs such as Sustainable Drainage Systems (SUDS) would help mitigate some of these effects sustainable. SUDS is natural drainage systems that simulate the natural drainage of a catchment and work in harmony to achieve an increase in ground infiltration and treatment of runoff; and a reduction in flow rates and volume of surface runoff, improving biodiversity and ultimately improving sustainability. However, the sustainability of SUDS devices is questionable because their component parts involve the use of natural resources. This study proposed the application newly designed namely Green Drainage System (GDS) using HM as channel bed. Therefore, it is important to determine the hydraulic characteristic of this module focusing on HM. This thesis investigated experimentally using tilting flume channel and rig simulator. HM as a bed channel was tested at three different slopes of 0.002, 0.005 and 0.008 and each slope consists of four different discharges. In order to verify the results of experimental measurements of the flume channel, the numerical modeling for all the cases was considered, under the same operating conditions with experimental measurements using porous media models and turbulence model (FLOW3D). Results agreed that the experimental and numerical results show good agreement. The maximum flow velocity occurs near the water surface with an increasing flow velocity at increasing depth. The steeper the slopes shows higher maximum water velocity near the water surface emphasized toward the end of flume channel. HM as the effect of porous bed on the turbulent characteristics of the flow in an open channel is different in comparison with the impermeable bed. The velocities are reduced with the decreasing of the water level due to the greater influence of the HM on the flow above the porous bed. It is apparent that the order of reduction velocity porous bed with HM >porous bed without HM > impermeable bed.
- ItemImplementation Of Safety Requirements By Contractors In The Construction Industry(2002-04)This thesis was carried out to study the implementation of safety requirements by contractors in the construction industry. In this research, we shall discuss on the safety of employees and examined this perspective in the construction industry. A case study was conducted to study the perfonnance of construction companies in the aspects of safety requirements at the construction site. The purpose of this study was to investigate whether contractors really understand safety requirements and properly implement safety at the workplace, in this case, the construction site. It was also aimed to observe the level of commitments from the management of the company towards the safety and to examine the awareness and understanding of the management in term of workplace safety. In addition, the objective of this study was also to examine the ways to improve the implementation of safety requirements by the contractors for their employees in the construction industry. Based on the case studied conducted, a systematic safety programme and plan was formulated for the construction companies.
- PublicationThe Influence Of Innate Psychological Needs On Intention To Stay Among Academics Employed At Malaysian Research Universities(2022-06)This study examined the relevance of innate psychological needs among Malaysian academics in the context of Malaysian research universities. It encompasses the innate psychological needs for autonomy, competence, and relatedness that can influence the intention to stay. A model was developed based on the self-determination theory to identify the predictors of innate psychological needs to examine how influential factors in three innate psychological needs can enhance the intention to stay through employee engagement. This study investigated how employee engagement plays a mediating role between innate psychological needs and the intention to stay. This study also investigated the relationship between employee engagement and the intention to stay. In addition, this study also examined how perceived organizational support moderates the relationship between innate psychological needs and employee engagement. Data was collected from 329 Malaysian academics from five Malaysian research universities via an online survey questionnaire developed from related literature. The collected data was then analyzed using Smart PLS. Findings indicate that innate psychological needs for autonomy (job autonomy), competence (social status), and relatedness (psychological ownership) have a significant positive impact on employee engagement.
- PublicationFormulation Of Fire Safety Evacuation Management Strategy For The Government Hospital Buildings(2022-12)The purpose of this research is not only to investigate fire safety evacuation management, but also to redefine the fulfilment of the design criteria of needed Means of Escape (MOE) by-Laws and other associated fire safety rules and regulations and to assess the building's compliance with the evacuation code. The study also seeks to develop parameters for fire safety management at the Government hospital buildings.