Mohamad Zaki Abdullah

Effect of Environmental Degradation on Mechanical Properties of Kenaf/Polyethylene Terephthalate Fiber Reinforced Polyoxymethylene Hybrid Composite

The main objective of this research is to investigate the effect of environmental degradation on the mechanical properties of kenaf/PET fiber reinforced POM hybrid composite. Kenaf and PET fibers were selected as reinforcements because of their good mechanical properties and resistance to photodegradation. The test samples were produced by compression molding. The samples were exposed to moisture, water spray, and ultraviolet penetration in an accelerated weathering chamber for 672 hours. The tensile strength of the long fiber POM/kenaf (80/20) composite dropped by 50% from 127.8 to 64.8 MPa while that of the hybrid composite dropped by only 2% from 73.8 to 72.5 MPa. This suggests that the hybrid composite had higher resistance to tensile strength than the POM/kenaf composite. Similarly, the results of flexural and impact strengths also revealed that the hybrid composite showed less degradation compared to the kenaf fiber composite. The results of the investigation revealed that the hybrid composite had better retention of mechanical properties than that of the kenaf fiber composites and may be suitable for outdoor application in the automotive industry.

Predicting The Tensile Properties Of Woven Kenaf/Polyethylene terephthalate (PET)Fiber Reinforced Polyoxymethylene (POM) Hybrid Laminate Composite

The analytical design of the hybrid composite predicts its tensile properties at different fiber orientation using classical lamination theory. The critical volume fraction of the high elongation fiberyields 0.39 which defines the composite of minimum strength. The high elongation fiber (PET) contributes more in raising the hybrid composite strengthwhile the low elongation fiber (Kenaf) increases the composite modulus more inthe longitudinal direction. Six layers hybrid composite laminates were analyzed. The stacking sequence used was symmetric angle ply (0 0 , 45 0 , 90 0 ) with an overall thickness of 12mm .The thermal expansion coefficient of the laminate increases more than that of the individual ply. The overall analytical results confirm that thehybrid composite tensile properties haveincreased significantly as compared to single fiber reinforced composite.

Influence of Recycling Frequency on Mechanical and Physical Properties of Kenaf Fiber Reinforced Polyoxymethylene Composite

ABSTRACT The main objective of this research is to investigate the effect of compression cycles and hybridization on mechanical and physical properties of kenaf fiber reinforced POM composite. In this study, kenaf, and polyethylene terephthalate (PET) fiber were used as reinforcements due to their excellent mechanical properties and resistance to thermal degradation during recycling process. The matrix used was polyoxymethylene (POM) copolymer due to its hydrophobic characteristics and good mechanical properties. In this investigation, two formulations namely POM/kenaf, and POM/kenaf/PET hybrid composite were carefully studied. The results of the investigation revealed that the tensile strength of both POM/kenaf, and POM/kenaf/PET after first recycling process dropped by approximately 83% and 67%, respectively. The tensile strength remained consistent after second and third compression cycle. The flexural strength of both composites also dropped by nearly 50% and 53%, but remained consistent after second and third compression cycle. However, the composite resistance to water absorption significantly increased due to less voids and micro-cracks observed after recycling process. The results obtained have shown that the recycled composites retained their mechanical properties after the last two compression cycles.

Casing strength degradation in thermal environment of steam injection wells

Degradation of the casing strength in relation with thermal cycles of steam injection process is still less explored in literature. In this paper, three-dimensional finite element (FE) analysis of casing strength degradation in thermal environment of steam injection wells is presented. 3D FE models consisting of casing-cement-formation system are developed in this study. Grade N80 casing is employed with the casing length of 3.048 m. In the analysis, cyclic thermal stresses induced on the casing in thermal environment of steam injection wells from 25 °C to 360 °C are first examined to verify the feasibility of the 3D FE models. Degradation of the casing strength in the thermal environment is subsequently investigated by applying an external pressure that represents formation pressure to the casing-cement system. The results show that the casing capability to resist the pressure is lowering as the number of thermal cycles extends, thus causing casing strength degradation in the thermal application. It is also shown that the casing may fail under external pressure below its specified collapse strength i.e. 10 % lower than the reference casing strength obtained at 360 °C.

Experimental Investigation of Energy Absorption of Partially Wrapped Thin-Walled Aluminium-Glass/Epoxy Tube Subjected to Quasi-Static Loading

This paper describes the failure modes and energy absorption capability of partially wrapped aluminium-glass/epoxy tubes, subjected to quasi-static loading. ‎These tubes are used in aircraft and automobiles applications. Aluminium tubes were partially wrapped with 4, 6 and 8 glass/epoxy layers, using filament winding process. The 90◦ fiber orientation was used for glass/epoxy layers. Quasi-static loading of partially wrapped tubes was carried out at 5mm/min speed, using the universal ‎testing machine. The experimental results revealed that partially wrapped aluminium tubes are 42.54%, 47.77% and 28.91% more ‎efficient in energy absorption as compared to the simple aluminium tubes. Furthermore, the effect of glass/epoxy layers on ‎failure modes has also been described.

Comparison of Energy Absorption of Aluminium-composite Tubes Subjected to Axial Loading

In this paper, energy absorption capability and failure modes of partially wrapped aluminium tubes have been studied. These tubes are used in the front side of automobiles and aircraft applications. Filament winding technique was used for partial wrapping of these tubes. Partially wrapping on the external surface of aluminium tubes was done with glass fibers, and epoxy resin, which is a composite material. Various composite layers and fiber angles were used in partial wrapping, which includes 4, 6 and 8 composite layers of ± 55° fiber angle. These tubes were subjected to axial crushing using the universal ‎testing machine, and testing speed was 5mm/min. Failure modes and energy absorption analysis were carried out after testing. The experimental results revealed that partially wrapped aluminium tubes are 3.81%, 8.13% and 17.06% more efficient in energy absorption as compared to the tubes without wrapping. Furthermore, the effect of composite layers and failure modes has also been described.

The effect of oleic acid as post spinning treatment on tensile strength of polyacrylonitrile fibers

Carbon fiber precursor was derived from Polyacrylonitrile (PAN) polymer, pitch based and cellulose rayon. Until now, the best precursor for carbon fibre is PAN polymer. This is because PAN polymer precursor have higher carbon content when subjected to heat treatment process. After spinning process, the PAN fibre will be soaked in a chemical before proceed to heat treatment process. The process is known as post spinning treatment process. In this study, oleic acid and the commercial chemical were applied as post treatment spinning chemical. After post spinning treatment, the fibre will be heat treated in 2 temperature zone represent stabilize and pre-carbonized region. The stabilize region is fixed at 250°C and the pre-carbonized region at 500°C. After heat treatment process, the fibre will be mechanically characterized using the low force single column universal tensile machine. Scanning Electron Microscope (SEM) micrograph was used to determine fibre diameter and surface microstructure. From the study, t...

Effect of wear on the burst strength of l-80 steel casing

Casing wear has recently become one of the areas of research interest in the oil and gas industry especially in extended reach well drilling. The burst strength of a worn out casing is one of the significantly affected mechanical properties and is yet an area where less research is done The most commonly used equations to calculate the resulting burst strength after wear are Barlow, the initial yield burst, the full yield burst and the rupture burst equations. The objective of this study was to estimate casing burst strength after wear through Finite Element Analysis (FEA). It included calculation and comparison of the different theoretical bursts pressures with the simulation results along with effect of different wear shapes on L-80 casing material. The von Misses stress was used in the estimation of the burst pressure. The result obtained shows that the casing burst strength decreases as the wear percentage increases. Moreover, the burst strength value of the casing obtained from the FEA has a higher value compared to the theoretical burst strength values. Casing with crescent shaped wear give the highest burst strength value when simulated under nonlinear analysis.

Interfacial Shear Stress in Kenaf/Polyethylene Terephthalate Fiber Reinforced Polyoxymethylene Composite

The mechanical properties of fibre reinforced polymer composites strongly depend on the interfacial bonding between fibre and matrix. The main objective of this paper is to compare the interfacial bonding between kenaf fibre reinforced POM with that of PET fibre reinforced POM in a hybrid composite. Continuous twisted kenaf, and PET yarn were used for the investigation. Each fibre yarn was half embedded in POM by compression moulding. The yarns were extracted from the matrix by single fibre pull out test method. The result of the investigation revealed that the interfacial shear strength of approximately 31.4 MPa between kenaf and POM is higher compared to 24.3 MPa obtained between PET fibre and POM. This may be due to higher surface energy of kenaf fibre with respect to POM in the composite The FESEM micrograph further demonstrates good interfacial adhesion between kenaf and POM in the composite.

Finite Element Analysis of Casing Material Behavior in Steam Injection Well Operations

Casing design is one of the most important parts of the well planning in the oil and gas industry. Various factors affecting the casing material needs to be considered by the drilling engineers. Wells partaking in thermal oil recovery processes undergo extreme temperature variation and this induces high thermal stresses in the casings. Therefore, forecasting the material behavior and checking for failure mechanisms becomes highly important. This paper uses Finite Element Methods to analyze the behavior two of the frequently used materials for casing - J55 and L80 steels. Modeling the casing and application of boundary conditions are performed through Ansys Workbench. Effect of steam injection pressure and temperature on the materials is presented in this work, indicating the possibilities of failure during heating cycle. The change in diameter of the casing body due to axial restriction is also presented. This paper aims to draw special attention towards the casing design in high temperature conditions of the well.