Mohd Afendi Rojan
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Preferred name
Mohd Afendi Rojan
Official Name
Mohd Afendi , Rojan
Alternative Name
Afendi, Mohd
Rojan, M. Afendi
Afendi Rojan, M.
Afendy, M.
Rojan, M. A.
Mohd Afendi, R.
Afendi, M.
Main Affiliation
Scopus Author ID
57188766103
Researcher ID
GQR-0248-2022

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  • Publication
    Finite element modelling of thin intermetallic compound layer fractures
    ( 2017)
    Ooi Eang Pang
    ;
    Ruslizam Daud
    ;
    Nasrul Amri Mohd Amin
    ;
    Mohd Afendi Rojan
    ;
    Mohd Shukry Abd Majid
    A thin intermetallic compound (IMC) of solder ball joint induces strong stress concentration between the pad and solder where a crack propagated near the IMC layer. The fracture mechanism of the IMC layer is complex due to the effect of IMC thickness, crack length, solder thickness and Young’s Modulus. At present, there is still an undefined exact geometrical model correlation for numerical simulations of IMC layer fracture. Thus, this paper aims to determine the accuracy of IMC layer models subjected to crack-to-width length ratio (a/W) in correlation with the ASTM E399-83 Srawley compact specimen model using finite element (FE) analysis. Several FE models with different geometrical configurations have been proposed under 10 MPa tensile loading. In this study, the two dimensional linear elastic displacement extrapolation method (DEM) is formulated to calculate the stress intensity factor (SIF) at the crack tip. The study showed that with an error of 0.58% to 0.59%, a width of 2.1 mm and a height of 1.47 mm can be recommended as the best geometrical model for IMC layer fracture modelling which provides a wider range for a/W from 0.45 to 0.85 instead of from 0.45 to 0.55. This result is significant as it presents a method for determining fracture parameters at thin IMC layers with a combination of singular elements with meshes at different densities which is tailored to the Srawley model.
  • Publication
    Finite element modelling of thin intermetallic compound layer fractures
    ( 2017)
    Ooi Eang Pang
    ;
    Ruslizam Daud
    ;
    Nasrul Amri Mohd Amin
    ;
    Mohd Afendi Rojan
    ;
    Mohd Shukry Abdul Majid
    A thin intermetallic compound (IMC) of solder ball joint induces strong stress concentration between the pad and solder where a crack propagated near the IMC layer. The fracture mechanism of the IMC layer is complex due to the effect of IMC thickness, crack length, solder thickness and Young’s Modulus. At present, there is still an undefined exact geometrical model correlation for numerical simulations of IMC layer fracture. Thus, this paper aims to determine the accuracy of IMC layer models subjected to crack-to-width length ratio (a/W) in correlation with the ASTM E399-83 Srawley compact specimen model using finite element (FE) analysis. Several FE models with different geometrical configurations have been proposed under 10 MPa tensile loading. In this study, the two dimensional linear elastic displacement extrapolation method (DEM) is formulated to calculate the stress intensity factor (SIF) at the crack tip. The study showed that with an error of 0.58% to 0.59%, a width of 2.1 mm and a height of 1.47 mm can be recommended as the best geometrical model for IMC layer fracture modelling which provides a wider range for a/W from 0.45 to 0.85 instead of from 0.45 to 0.55. This result is significant as it presents a method for determining fracture parameters at thin IMC layers with a combination of singular elements with meshes at different densities which is tailored to the Srawley model.
  • Publication
    Dielectric properties and microwave absorbing properties of silicon carbide nanoparticles and silicon carbide nanowhiskers
    ( 2023-04)
    Phey Yee Foong
    ;
    Voon Chun Hong
    ;
    Lim Bee Ying
    ;
    Teh Pei Leng
    ;
    Mohd Afendi Rojan
    ;
    Subash Chandra Bose Gopinath
    ;
    Nor Azizah Parmin
    ;
    Mohd Khairuddin Md Arshad
    ;
    Yeng Seng Lee
    ;
    Ruslinda A. Rahim
    ;
    Uda Hashim
    Silicon carbide (SiC) is well known for their outstanding microwave absorbing properties. SiC nanomaterials (SiCNMs) are expected to have better microwave absorption performance due to their high specific surface area. To date, no study was reported to compare the dielectric properties and microwave absorbing properties of different type of SiCNMs. Therefore, the objective of this paper is to compare the dielectric properties and microwave absorption properties of different types of SiCNMs. In this paper, SiC nanoparticles (SiCNPs) and SiC nanowhiskers (SiCNWs) were characterised using SEM and XRD. In addition, their dielectric properties and microwave absorbing properties were measured using network analyser and transmission line theory. It was found that SiCNWs achieved higher dielectric constant and loss factor which are and εr’ =17.94 and εr″ = 2.64 compared to SiCNPs that only achieved εr’ = 2.83 and εr″ = 0.71. For microwave absorbing properties, SiCNWs and SiCNPs attained minimum reflection loss of -10.41 dB and -6.83 dB at 5.68 GHz and 17.68 GHz, respectively. The minimum reflection loss of SiCNPs and SiCNWs obtained in this study is much lower than the nanometer-SiC reported previously. These results suggested that SiCNWs can be an ideal candidate of microwave susceptors for various microwave applications
  • Publication
    Microwave Welding of Thermoplastic using Silicon Carbide Nanowhiskers as Susceptor: Effect of Heating Duration
    ( 2024-06-01)
    Foong P.Y.
    ;
    Voon Chun Hong
    ;
    Lim B.Y.
    ;
    Teh P.L.
    ;
    Yeoh C.K.
    ;
    Mohd Afendi Rojan
    ;
    Nor Azizah Parmin
    ;
    Subash Chandra Bose Gopinath
    ;
    Low F.W.
    ;
    Kashif M.
    ;
    Rahman N.A.A.
    ;
    Sam Sung Ting
    ;
    Perumal V.
    Microwave welding is becoming more popular than conventional joining methods due to its advantages such as rapid and localised heating as well as applicable to components with complicated geometry. Previously reported susceptor, such as carbonaceous materials and conductive polymers, are toxic and the welding process involving these susceptors is time-consuming. Because of its exceptional microwave absorption and biocompatibility, silicon carbide nanowhiskers (SiCNWs) was employed as the microwave susceptor for microwave welding. Microwave welding in this study comprises of only three simple steps: SiCNWs suspension preparation, SiCNWs application and microwave heating. The weld strength of welded joint was then characterised using tensile test and energy dispersive x-ray spectroscopy equipped scanning electron microscopy (EDS-SEM) to study its mechanical properties and cross-section microstructure. The influence of microwave irradiation time was studied in this study, and it is found that the weld strength rose with the extension of microwave irradiation time, until a maximum weld strength of 1.61 MPa was achieved by 17 s welded joint. The development of SiCNWs reinforced PP nanocomposite welded joint layer is responsible for the enhanced weld strength. Prolonged heating duration may also result in flaws such as void formation at the welded joint, which subsequently lowered the weld strength to 0.60 MPa when the heating duration was extended to 20 s. In sum, a strengthen welded joint can be formed with rapid microwave heating under the proper control of heating duration.
  • Publication
    The Characterization of J-Integral for Elastic-Plastic Crack Growth Evaluation using Finite Element Analysis
    ( 2021-01-01)
    Heng S.H.
    ;
    Muhamad Safwan Muhamad Azmi
    ;
    Mohd Afendi Rojan
    ;
    Mohd Sani Mohamad Hashim
    ;
    Abdul Halim Ismail
    J-integral is a fracture mechanic parameter that can be used to characterize elastic-plastic fracture mechanic (EPFM) behavior. The path independent characteristic in J-integral is proposed by Rice [1], and it is widely used in a lot of research. Another approach is the load-displacement approach, where the J-integral is calculated by the area under the load-displacement curve. However, the validity of the J-integral value by load-displacement approach is yet to be confirmed. This paper is aimed to investigate the effect of crack length ratio of CT specimen to J-integral value by two approaches: path-integral approach and load-displacement approach. Finite element analysis of compact tension (CT) model with crack length ratio a/W between 0.2 to 0.5 was carried out under displacement δ between 0.2 to 1.0 mm using ANSYS parametric design language (APDL). The J value by path integral approach, Jpath is compared to the value calculated from load-displacement approach, Jp-d. It was found that path independency occurs for J value evaluated from path integral approach. A correction factor needs to be introduced since the load-displacement approach cannot be used for shallow crack cases
  • Publication
    Influence of friction stir welding parameters on joint defects, temperature and hardness of AA6061-T6 and S27JR mild steel FSW joint
    ( 2021-10-25)
    Wan Mohd Syafiq Wan Sulong
    ;
    Mohd Afendi Rojan
    ;
    Mazlee Mohd Noor
    The influence of welding parameters such as tool plunge depth, tool travel speed and tool tilt angle on welding temperature during friction stir welding of AA6061-T6 and S275JR mild steel was the focus of this research. Thermocouple placed in the aluminum alloy plate prior to welding was used to measure the temperature during the welding of joints under different set of parameter values. Joint appearance as well as defects occurring on the surface or within the joint was observed. Microhardness profiles were also taken by measuring microhardness values across the cross section of joints. Excessive flash, tunnel defects and insufficient welding were the type of weld defects observed on different joints with different parameters. Defects were attributed to the varied parameter values affecting the heat generation as well as the flow of the plasticized material. Highest temperature was recorded by the joint fabricated using the largest tool plunge depth, owing to the increased downwards pressure. Microhardness profiles were seen to be similar for all the welded joints. A “plateau” of low microhardness value was observed for all joints associated with the thermomechanically affected zone (TMAZ) and heat affected zone (HAZ). A wider plateau was observed for joints welded with higher tool plunge depth due to higher temperature.
  • Publication
    Effect of FSW parameters on temperature profile and grain size of AA6061-T6 and S275JR mild steel FSW joint
    ( 2021-05-03)
    Wan Mohd Syafiq Wan Sulong
    ;
    Mohd Afendi Rojan
    ;
    Mazlee Mohd Noor
    Friction stir welding (FSW) is a solid-state welding technique used to join materials such as aluminum alloy, magnesium alloy, steel and titanium. The process involves relatively low process temperatures compared to other conventional welding techniques. Welded material undergoes severe plastic deformation driven by the rotating FSW tool, which causes dynamic recrystallization of grains. In this study, the temperature during the welding of AA6061-T6 aluminum alloy and S275JR mild steel was recorded using K-type thermocouple. Grains in the stir zone (SZ) of joints were observed in order to measure the grain size. Samples were etched with Keller's reagent to reveal its microstructure. It was seen that the highest temperature was recorded when welding with a high tool plunge depth. Decreasing tool travel speed was seen to increase temperature readings. The lowest temperature was recorded when using a high tool tilt angle due to a reduced contact area between tool shoulder and weld piece. Largest observed grain size was measured in the SZ of the joint welded with a high tool plunge depth, due to the high process temperature experienced by the joint during welding.
  • Publication
    Engine Performance Analysis by Studying Heat Transfer in the Valve Seat through Steady-State Thermal Simulation
    ( 2021-12-14)
    Mohamad Aniq Syazwan Mohamed Hassan
    ;
    Shahriman Abu Bakar
    ;
    Zuradzman Mohamad Razlan
    ;
    Nur Saifullah Kamarrudin
    ;
    Wan Khairunizam Wan Ahmad
    ;
    Mohd Sani Mohamad Hashim
    ;
    Azizi Harun
    ;
    Ishak Ibrahim
    ;
    Azizul Aziz I.
    ;
    Zunaidi Ibrahim
    ;
    Mohd Khairul Faizi Abd Rahman
    ;
    Muhammad Faiz Hilmi Rani
    ;
    Anas Abdul Rahman
    ;
    Mohd Afendi Rojan
    ;
    Rishan Murali
    As the engine reached high speed, the exhaust valve temperature increased exponentially due to the exhaust gas produced by the combustion process between the mixture of air and fuel within the combustion chamber of the internal combustion engine. The valve is subjected to thermal loading due to high temperature and pressure within the cylinder, which must withstand a material temperature for sustainable and optimal operation. To avoid this loss, a perfect medium must be prepared to ensure that the heat is extracted smoothly. This can be done when the valve is in contact with the seat and there is a periodic heat transfer contact. Therefore, it is imperative to research the correlation between valve and valve seat to understand the two sections' heat transfer mechanism. In this study, thermal contact analysis was used to identify heat transfer between the valve and the valve seat as both parts are interconnected. This research also has an interest in studying the two surface conduction mechanisms as the exhaust valve closed in steady-state conditions. Thus, this study portrays a significant method, particularly for the determining the distribution of temperature, heat flux, and heat flux direction between the valve and its seat using ANSYS Workbench.
  • Publication
    Effect of loading protocol on the mechanical properties of 316L stainless steel
    ( 2021-10-25)
    Heng S.H.
    ;
    Muhamad Safwan Muhamad Azmi
    ;
    Mohd Afendi Rojan
    ;
    Mohd Sani Mohamad Hashim
    ;
    Mohd Nasir Ayob
    ;
    Abdul Halim Ismail
    ;
    Muhamad Saifuldin Abdul Manan
    ;
    Abdullah S.
    Two types of loading protocol, i.e., monotonic loading and cyclic loading, were compared to investigate the effect on the mechanical properties of 316L stainless steel. The specimen used is a dog-bone specimen in accordance with ASTM E8 and ASTM E606 standard. For cyclic loading, the multiple-step method is used to obtain the hysteresis loop of the material. A total of 13 strain amplitude conditions had been carried out, ranging from 0.05%-0.65%. The stress-strain curve shows that the cyclic stress-strain curve is higher than the monotonic stress-strain curve due to the cyclic hardening behaviour in the 316L stainless steel. The cyclic hardening behaviour increases the ultimate tensile stress of the material. However, when the material gains its strength through cyclic hardening, the ductility in the material will decrease.
  • Publication
    Effect of Microwave Power and Clamping Pressure on the Microwave Welding of Polypropylene Using Silicon Carbide Nanowhiskers as Microwave Susceptor
    ( 2022-01-01)
    Foong P.Y.
    ;
    Voon Chun Hong
    ;
    Lim B.Y.
    ;
    Teh P.L.
    ;
    Mohd Afendi Rojan
    ;
    Nor Azizah Parmin
    ;
    Subash Chandra Bose Gopinath
    ;
    Mohd Khairuddin Md Arshad
    ;
    Low F.W.
    ;
    Mahalingam S.
    ;
    Manap A.
    ;
    Rahim R.A.
    ;
    Uda Hashim
    Due to their excellent dielectric properties and the rapid response to microwave irradiation, silicon carbide nanowhiskers (SiCNWs) were employed as microwave susceptor in this study to absorb microwave and locally melt the surrounding polypropylene (PP) substrates for the joining of PP substrates. Complete welded joint is formed after the melted PP was cooled and resolidified. Other than microwave susceptor, SiCNWs also acted as the nanofillers in strengthening the welded joint through the formation of SiCNWs reinforced PP nanocomposite at the interface of PP substrates. Besides, the effect of microwave power on the microwave welding of PP substrates using SiCNWs as susceptor was studied and reported. It was found that the tensile strength and modulus of elasticity of the welded joint improved as microwave power increased. However, it deteriorates the flexibility of the welded joint as high stiffness SiCNWs were incorporated deeper into the PP matrix which restricted the PP chain mobility. Aside from microwave power, clamping pressure is also critical in determining the mechanical properties of a welded joint. When compared to unclamped welded joint, the tensile strength, modulus of elasticity and flexibility of welded joint subjected to clamping pressure improved drastically. Moreover, the tensile strength of welded joint increased when the clamping pressure was increased from P1 to P3, but decreased when the clamping pressure was further increased to P4 due to the occurrence of flashing at welded joint. The formation mechanism of SiCNWs reinforced PP welded joint was also proposed in this study. Compared to conventional welding, this welding process is easy, straightforward and is able to produce welded joint with outstanding mechanical properties via precise controlling of the processing parameters. Thus, microwave welding is thought to offer an option for the joining of thermoplastics and other applications.