Now showing 1 - 10 of 148
  • Publication
    Regression analysis of the dielectric and morphological properties for porous Nanohydroxyapatite/Starch composites: a correlative study
    This paper aims to investigate the dielectric properties, i.e., dielectric constant (ε′), dielectric loss factor (ε″), dielectric tangent loss (tan δ), electrical conductivity (σ), and penetration depth (Dp), of the porous nanohydroxyapatite/starch composites in the function of starch proportion, pore size, and porosity over a broad band frequency range of 5 MHz–12 GHz. The porous nanohydroxyapatite/starch composites were fabricated using different starch proportions ranging from 30 to 90 wt%. The results reveal that the dielectric properties and the microstructural features of the porous nanohydroxyapatite/starch composites can be enhanced by the increment in the starch proportion. Nevertheless, the composite with 80 wt% of starch proportion exhibit low dielectric properties (ε′, ε″, tan δ, and σ) and a high penetration depth because of its highly interconnected porous microstructures. The dielectric properties of the porous nanohydroxyapatite/starch composites are highly dependent on starch proportion, average pore size, and porosity. The regression models are developed to express the dielectric properties of the porous nanohydroxyapatite/starch composites (R2 > 0.96) in the function of starch proportion, pore size, and porosity from 1 to 11 GHz. This dielectric study can facilitate the assessment of bone scaffold design in bone tissue engineering applications.
  • Publication
    The effect of stacking sequence on fatigue behaviour of hybrid pineapple leaf fibre/carbon-fibre-reinforced epoxy composites
    ( 2021) ; ; ; ;
    Mohamed Thariq Hameed Sultan
    ;
    Ain Umaira Md Shah
    ;
    Kamarul Arifin Ahmad
    ;
    Adi Azriff Basri
    This study examined the fatigue behaviour of pineapple leaf fibre/carbon hybrid laminate composites under various stacking sequences. The vacuum infusion technique was used to fabricate the symmetric quasi-isotropic oriented laminates, in which the stacking was varied. The laminate was tested under static and fatigue tensile load according to ASTM D3039-76 and ASTM D3479-96, respectively. Maximum tensile strength and modulus of 119.34 MPa and 6.86 GPa, respectively, were recorded for the laminate with external PALF ply and internal carbon ply oriented at [± 45°2, 0°/90°2]s (PCCP_45090). The fatigue tests showed that PCCP_45090 and CPPC_09045 (with internal PALF ply and external carbon ply oriented at [0°/90°2, ± 45°2]s) exhibited a higher useful life, especially at the high-stress level of the ultimate tensile strength. The normalised stress against the number of cycles showed that the stacking sequences of different ply orientations affected the fatigue behaviour more than the stacking sequences of the material. The laminate stacking sequence significantly affected the hysteresis energy and stiffness evolution. The scanning electron microscopy images showed that the fatigue failure modes included fibre pull-out, fibre breakage, matrix cracking, debonding, and delamination. The study concluded that PCCP_45090 exhibited an outstanding fatigue performance.
  • Publication
    Electric Discharge Machining on Stainless Steel Using a Blend of Copper and Fly Ash as the Electrode Material
    ( 2022-10-01)
    Balamurugan P.
    ;
    Uthayakumar M.
    ;
    Pethuraj M.
    ;
    Mierzwiński D.
    ;
    Korniejenko K.
    ;
    In the current work, several composites made with fly ash reinforcements are used to conduct electrical discharge machining (EDM) on stainless steel that is commercially accessible. Four composites were prepared with 2.5 to 10% reinforcement of fly ash with steps of 2.5%, copper is used as the matrix material. The specimens were created using the powder metallurgy method, which involved compaction pressures of 450 MPa and 900 °C for 90 min of sintering. The prepared composites are used as the electrode tool for EDM. EDM studies were carried out at two different current amplitudes (5A and 15A) by maintaining the Pulse on time (100 µs), Pulse off time (50 µs), and the depth of machining as 2 mm. The findings show that the addition of more fly ash to the copper matrix increased the material removal rate when cutting the SS304 plate and had a negative impact on the tool. The composite loses its ability to transfer heat during machining as the level of fly ash increases, raising the temperature in the copper matrix and causing the copper to melt more quickly at the electrode interface during machining, leading to increased electrode wear. While tool life was reduced because of the increase in current amplitude, machinability was enhanced.
  • Publication
    Physical, thermal, and mechanical properties of highly porous polylactic acid/cellulose nanofibre scaffolds prepared by salt leaching technique
    ( 2021)
    Revati Radakisnin
    ;
    ; ;
    Mohd Faizal Mat Tahir
    ;
    ;
    Hassan Al Alshahrani
    This study aimed to prepare and characterise polylactic acid (PLA) reinforced with cellulose nanofibre (CNF) from a Pennisetum purpureum-based composite scaffold and determine its structural and mechanical properties. Porous scaffolds with CNF compositions of 5‒20 wt% in the PLA matrix were developed using solvent casting and particulate leaching of its porogen at 90 wt% of loadings. Morphology studies using field emission scanning electron microscopy revealed that the scaffolds had well-interconnected pores with an average pore size range of 67‒137 µm and porosity >76%. X-ray diffraction confirmed the interconnectivity and homogeneity of the pores and the fibrous structure of the scaffolds. The compressive strength of the fabricated scaffolds varied between 2.34 and 6.66 MPa, while their compressive modulus was between 1.95 and 6.04 MPa for various CNF contents. Furthermore, water absorption and thermal degradation studies showed that the scaffold had good hydrophilicity and improved thermal stability. These findings highlight the need to modify the pore structure and mechanical performance simultaneously for tissue engineering. Thus, this study concludes that the developed PLA scaffolds reinforced with CNF from Pennisetum purpureum are potential candidates for cell attachment and extracellular matrix generation.
  • Publication
    Fatigue life investigation of UIC 54 rail profile for high speed rail
    ( 2017-10-29)
    Gurubaran Panerselvan
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    ;
    Nur Fareisha M. A.
    ;
    ;
    Haftirman I.
    ;
    This study is to investigate the fatigue life of high speed rail in Malaysia. This paper describes about the experimental and simulation analysis investigation on fatigue life of rail profile UIC 54 using bulk specimen according to ASTM E 466-15 standard. The Fatigue life testing was performed in the fatigue testing machine (Instron 8800) 100 kN. Meanwhile, the fatigue life analysis was performed in ANSYS Workbench 14.5. Furthermore, the stress levels for experimental testing were applied as 16.7%, 25%, 35%, 50%, 58.3%, 66.77% and 75% with machine frequency of 20 Hz. Apart from that, the total fatigue life cycles for rail profile UIC 54 were acquired from both experimental and simulation. The fatigue life S-N curves were plotted and validated with the results of the simulation analysis with experimental results.
  • Publication
    Finite element modelling of thin intermetallic compound layer fractures
    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
    Structural, morphological and thermal properties of cellulose nanofibers from napier fiber (Pennisetum purpureum)
    ( 2020-09-01)
    Radakisnin R.
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    ; ;
    Jawaid M.
    ;
    Sultan M.T.H.
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    The purpose of the study is to investigate the utilisation of Napier fiber (Pennisetum purpureum) as a source for the fabrication of cellulose nanofibers (CNF). In this study, cellulose nanofibers (CNF) from Napier fiber were isolated via ball-milling assisted by acid hydrolysis. Acid hydrolysis with different molarities (1.0, 3.8 and 5.6 M) was performed efficiently facilitate cellulose fiber size reduction. The resulting CNFs were characterised through Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), particle size analyser (PSA), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The FTIR results demonstrated that there were no obvious changes observed between the spectra of the CNFs with different molarities of acid hydrolysis. With 5.6 M acid hydrolysis, the XRD analysis displayed the highest degree of CNF crystallinity at 70.67%. In a thermal analysis by TGA and DTG, cellulose nanofiber with 5.6 M acid hydrolysis tended to produce cellulose nanofibers with higher thermal stability. As evidenced by the structural morphologies, a fibrous network nanostructure was obtained under TEM and AFM analysis, while a compact structure was observed under FESEM analysis. In conclusion, the isolated CNFs from Napier-derived cellulose are expected to yield potential to be used as a suitable source for nanocomposite production in various applications, including pharmaceutical, food packaging and biomedical fields.
  • Publication
    Failure envelope modelling of glass/epoxy composite pipes using system identification method
    The paper aims to model the performance of the Glass Fibre Reinforced Epoxy (GRE) composite pipe under multiaxial loading via system identification approach. System identification modelling depends on the input and output data of the experimental result. In this study, the experimental data used are obtained from a pressurised test rig. The model is based on pure hydrostatic (2H: 1A) loading using GRE pipes with three different winding angles (±45°, ±55°, ±63°). Several models based on different model structures are derived for comparison to obtain the best modelling accuracy. The result shows that the transfer function method could model and has the highest efficiency compared with the experimental result. The ±45°pipe model have achieved 92.41% and 85.13% for both its hoop and axial model. The ±55°pipe model has achieved 96.64% and 86.1%. Follow by the ±63°which the best fit is 92.41% and 94.26%. At the last part of this research, the ±55°pipe model and experimental data has been use to identified when the damage occur and found that the axial strain of 78 bar can damage the experimental pipe in this research.
  • Publication
    Influence of pre-heating technique on the titanium alloy for machinability using mill insert
    ( 2023-10-27)
    Vemanaboina H.
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    Ananda K.E.
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    ;
    Naidu B.V.V.
    ;
    Pugazhenthi R.
    Ti6Al4V is a composite material with low density (4.5 g/cm3), melting point (16680C), and modulus of elasticity (107 GPa). Ti6Al4V's ambient temperature tensile values can reach 1400 MPa, and its yield strength is noted. The Ti6Al4V alloys are also extremely malleable, making them simple to make and machine. The cutting capabilities of titanium compound will be improved by introducing and registering a novel technique presented in this work. Pre-heating the workpiece with an induction coil heating device before end milling on a vertical machining centre will be studied (VC450-Spinner). WC-Co/PCD inserts placed 25 mm across the mill (R390-025B25-11M/R390-170408E-NLH13A) were thoroughly studied with general preheating method on Ti6Al4V machinability metrics like span of tool, Ra & Fc, noise, anomalies, tool, and morphology. Similarly, bare WC-Co was widely used in warmed machining (straight around multiple times compared to room temperature machining), and estimates of tool life are basically greater than those for cutting with PCD in room temperature machining. Preheated milling reduces shaking and noise, which in turn reduces cutting power and increases the lifespan of the tool. Preheated milling also increased chip-device contact length, lowering tool wear. The device also improved tool life and surface roughness by optimising cutting settings and preheating temperature. Lastly, preheating improved bare WC-Co execution and PCD tool life predictions under room temperature milling. By reducing disturbance and noise and the resulting cutting power, preheated milling promotes longer tool life. Preheated milling increases chip-tool contact length, which reduces tool wear.
  • Publication
    The effect of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (Palf)/carbon hybrid laminate composites
    In this paper, the effects of stacking sequence and ply orientation on the mechanical properties of pineapple leaf fibre (PALF)/carbon hybrid laminate composites were investigated. The hybrid laminates were fabricated using a vacuum infusion technique in which the stacking sequences and ply orientations were varied, which were divided into the categories of cross-ply symmetric, angle-ply symmetric, and symmetric quasi-isotropic. The results of tensile and flexural tests showed that the laminate with interior carbon plies and ply orientation [0â—¦, 90â—¦ ] exhibited the highest tensile strength (187.67 MPa) and modulus (5.23 GPa). However, the highest flexural strength (289.46 MPa) and modulus (4.82 GPa) were recorded for the laminate with exterior carbon plies and the same ply orientation. The fracture behaviour of the laminates was determined by using scanning electron microscopy, and the results showed that failure usually initiated at the weakest PALF layer. The failure modes included fibre pull-out, fibre breaking, matrix crack, debonding, and delamination.