Aidy Ali | Universiti Pertahanan Nasional Malaysia (original) (raw)

Books by Aidy Ali

In this study, fatigue life of natural fiber reinforced composite materials was predicted due to ... more In this study, fatigue life of natural fiber reinforced composite materials was predicted due to manufacturing defects fatigue damage modes. Kenaf bast fibers were used to fabricate natural fiber composite materials with epoxy as a binding material. The Kenaf fiber reinforced composites were manufactured using a hand lay-up process. The defects in Kenaf reinforced composite materials were determined by a non-destructive technique using Infrared (IR) thermal imager. The thermography analyses were verified by optical microscope and scanning electron microscope (SEM) investigations. Then, the Mathematical model for estimating fatigue life by IR thermal imaging technique based on damage accumulation model is proposed. This proposed model is named as SIR thermal imaging fatigue life model. Determinations of fatigue damage has been predicted and it found that it damage has been fixed with the predicting results. SIR model proposed that 60% kenaf epoxy with thickness 0.3 cm is recommended as the best formulation to fabricate the specimens due to a longer fatigue life recorded and the result obtained from the fatigue cyclic tension test shows that 60% kenaf epoxy with thickness 0.3 cm had the highest fatigue resistance as indicated by a highest range of stress level, 119.71-53.20 MPa.

Different grades of sisal fibres (S3, STOW, and SUG) were immersed in five different treatment so... more Different grades of sisal fibres (S3, STOW, and SUG) were immersed in five different treatment solutions: sodium hydroxide (NaOH) for 24 h; silane for 24 h; and NaOH followed by silane for 6, 12, and 24 h. The treated fibres were tested for bonding strength using the micro-droplet method. It was established that NaOH and silane treatments improved bonding strength with the unsaturated polyester resin that was used. However, it can be concluded that NaOH followed by silane (each for 6 h) produced the highest bonding strength compared with the other combined treatments. This is most likely because of fibre erosion caused by the chemicals in the other treatments, which causes fibres to lose the ability to bond with the resin. Fibres treated with silane had the highest bonding strength. The tensile mechanical properties, characterised using the single-fibre test method according to the ASTM standard C1557-03 (2008), showed that the NaOH treatment improved ultimate tensile strength, while the silane treatment decreased ultimate tensile strength for all sisal grades. Nevertheless, the ultimate tensile strength was reduced when the duration of the combined treatments was increased. The highest results for the mechanical properties were obtained from the combined treatments of NaOH followed by silane (each for 6 h).

The fatigue and fracture properties of bamboo fiber composites made of woven layers were investig... more The fatigue and fracture properties of bamboo fiber composites made of woven layers were investigated. This study utilized a specific type of bamboo species named Gigantochloa scortechinii (Buluh Semantan). In these experiments, unsaturated polyester (UP) and bamboo fiber (BF) strips were prepared through a hand lay-up technique using 3-mm thick aluminum mould. The composite bamboo strips had a thickness of 1.5 mm. The strips were woven together to make a single layer. The layer was then laminated into several thicknesses. The specimens were then characterized using fatigue and fracture tests. A fatigue limit of 30 MPa and fracture toughness of 5 to 8 MPa √í µí± were obtained. These findings suggest that the bamboo strips, based on unsaturated polyester, provided relatively good fatigue and fracture properties and a good method of reinforcing fibers to combat fatigue and fracture failures.

Papers by Aidy Ali

Thin-walled Structures, 2009

A theoretical solution for thermoelastic analysis of functionally graded (FG) rotating disk with ... more A theoretical solution for thermoelastic analysis of functionally graded (FG) rotating disk with variable thickness based on first-order shear deformation theory (FSDT) is presented. Material properties and disk thickness profile are assumed to be represented by power law distributions. A semi analytical solution for displacement field is given under two types of boundary conditions applied for solid and annular disks. The effects of the material grading index and the geometry of the disk on the stress and displacement fields are investigated. Mechanical responses homogeneous disks versus FG disks are compared and verified with the known results in the literature. It is seen that the transverse displacements in FG solid disks with roller support condition at the outer surface remain between the minimum displacement value for the full-ceramic disk and the maximum displacement value for the full-metal disk. It is found that the transverse displacements in FG mounted disks with free condition at outer surface may not lie in between the displacement values for full-metal and full-ceramic disks. It is observed that the absolute moment resultant for FG mounted disk with concave profile is lowest compared to the FG mounted disk with linear or convex profile. It can be concluded that the gradation of the metal–ceramic components and the geometry of the disk are significant parameters in the thermomechanical responses of FG disks.

Applied Mathematical Modelling, 2009

The theoretical formulation for bending analysis of functionally graded (FG) rotating disks based... more The theoretical formulation for bending analysis of functionally graded (FG) rotating disks based on first order shear deformation theory (FSDT) is presented. The material properties of the disk are assumed to be graded in the radial direction by a power law distribution of volume fractions of the constituents. New set of equilibrium equations with small deflections are developed. A semi-analytical solution for displacement field is given under three types of boundary conditions applied for solid and annular disks. Results are verified with known results reported in the literature. Also, mechanical responses are compared between homogeneous and FG disks. It is found that the stress couple resultants in a FG solid disk are less than the stress resultants in full-ceramic and full-metal disk. It is observed that the vertical displacements for FG mounted disk with free condition at the outer surface do not occur between the vertical displacements of the full-metal and full-ceramic disk. More specifically, the vertical displacement in a FG mounted disk with free condition at the outer surface can even be greater than vertical displacement in a full-metal disk. It can be concluded from this work that the gradation of the constitutive components is a significant parameter that can influence the mechanical responses of FG disks.

Key Engineering Materials, 2011

Abstract The work presents a summary of previous studies on fatigue crack propagation within vari... more Abstract The work presents a summary of previous studies on fatigue crack propagation within various Aluminum alloys. The effective characteristics on crack growth are first highlighted and the influence of surface engineering such as polishing, shot peening and skimming to enhance the failure resistance are discussed. Several different existing developed models for predicting the rate of crack propagation are compared in terms of incorporated effective parameters. Finally numerical and computational analyses as the ...

IOP Conference Series: Materials Science and Engineering, 2011

2008 International Conference on Microelectronics, 2008

Abstract This paper presents the full design, operational principle, structure and frequency resp... more Abstract This paper presents the full design, operational principle, structure and frequency response simulation of one-port Surface Acoustic Wave (SAW) Resonator using Micro Wave Office (MWO) and MATLAB used for passive wireless sensing of various measurands. Since SAW Resonators are widely used in radio frequency sensing application, the development and evolution of present day SAW devices has been possible only due to simultaneous efforts to simulate these devices and also it is desirable to evaluate the device prior to ...

Iop Conference Series: Materials Science and Engineering, 2011

In this study, the effect of controlled shot peening (CSP) treatment on the fatigue strength of a... more In this study, the effect of controlled shot peening (CSP) treatment on the fatigue strength of an ASTM A516 grade 70 carbon steel MIG-welded joint has been studied quantitatively. Metallurgical modifications, hardness, elemental compositions, and internal discontinuities, such as porosity and inclusions found in treated and untreated fusion welded joints, were characterized. The fatigue results of as-welded and peened skimmed joints were compared. It was observed that the effect of the CSP and skimming processes improved the fatigue life of the fusion weld by 63% on MIG-welded samples.

Journal of Failure Analysis and Prevention, 2009

Fatigue crack propagation through a friction stir welded (FSW) joint of 2024-T351 Al alloy is inv... more Fatigue crack propagation through a friction stir welded (FSW) joint of 2024-T351 Al alloy is investigated numerically. The governing relationships for predicting the crack behavior including incremental crack length, crack growth rate, and crack growth direction are presented. Stress intensity is calculated based on displacement correlation technique, and fatigue crack growth through the FSW joint is investigated under linear elastic fracture mechanics (LEFM) using the Paris model. The concepts of crack closure, residual stress, and stress relaxation are incorporated into the Paris model to support the final results. Maximum circumferential tensile stress method is applied to predict the crack growth direction. Finally, the numerical approaches are employed to the high number of elements in the framework of Fracture Analysis Code (FRANC2D/L) to simulate the fatigue crack propagation through the FSW joint including various zones with different material properties. Fatigue lifetime of the welded joint is predicted by implementing the same procedure for various loading values. The obtained numerical results are validated with the experimental work (Ali et al., Int J Fatigue 30:2030–2043, 2008).

Thin-walled Structures, 2009

Applied Mathematical Modelling, 2009

Key Engineering Materials, 2011

IOP Conference Series: Materials Science and Engineering, 2011

2008 International Conference on Microelectronics, 2008

Iop Conference Series: Materials Science and Engineering, 2011

Journal of Failure Analysis and Prevention, 2009

International Journal of Computational Methods, 2009

Iop Conference Series: Materials Science and Engineering, 2011

Stress intensity factor (SIF) is one of the most important parameters in fracture mechanics. Ther... more Stress intensity factor (SIF) is one of the most important parameters in fracture mechanics. Therefore there is essential request on investigation of the behavior of SIF. Due to extensive and practical usage of plate structures in components, hence the behavior of SIF through the thickness of plate has been done. The three dimensional (3D) plate has simulated in ABAQUS finite element software. Crack tip has been meshed by 20 quarter node elements. The results presented that the SIF in free surfaces of plate had minimum value and variation of SIFs approximately was constant through the thickness of plate except on free surface.

Transactions of The Society for Modeling and Simulation International, 2009

This paper presents the full design, operational principle, structure and frequency response simu... more This paper presents the full design, operational principle, structure and frequency response simulation of one-port Surface Acoustic Wave (SAW) Resonator using Micro Wave Office (MWO) and MATLAB used for passive wireless sensing of various measurands. Since SAW Resonators are widely used in radio frequency sensing application, the development and evolution of present day SAW devices has been possible only due to simultaneous efforts to simulate these devices and also it is desirable to evaluate the device prior to fabrication especially in cases where the characteristic of device material and dimensions have a major influence on the performance of the overall system. The equivalent circuit model approach has been used to simulate the frequency response of one-port SAW resonator base on gallium orthophosphate (GaPO4) with 5Â° cut-angle at 2.45 GHz under ISM band frequency for high temperature wireless application and it appears that this modeling is suitable for near resonance frequency, also measuring dielectric permittivity of GaPO4 at this frequency for use of modeling.

American Journal of Applied Sciences, 2009

Abstract Problem statement: Environment issue on the dumping of used household product is a big c... more Abstract Problem statement: Environment issue on the dumping of used household product is a big challenge nowadays. Towards green design, life cycle of a product is very crucial. This study discussed on recycling strategies which include reuse, service, remanufacture and recycle with or without disassembly by using Support Vector Machine Method (SVM). Approach: In early stage of prediction, the input parameters of wear-out life; technology cycle, level of integration, number of parts, reason for redesign and design cycle were ...

This paper presents an investigation of the capability of the acoustic emission (AE) technique in... more This paper presents an investigation of the capability of the acoustic emission (AE) technique in the processes of monitoring and detecting the variation of engine oil's viscosity via in-situ operation. The investigations were conducted on an 8.5-hp single cylinder of four strokes with a water cooling engine. One single grade engine oil's condition has been put to the test; namely, SAE 40 VI 96. The oil condition in the engine was successfully monitored based on the AE signatures generated by the interaction between the piston surface and the layer of the oil during the time that the engine was in operation. The generated AE signatures were captured using an AE wide band transducer that was bonded outside the engine block and located at the lower part of the bottom dead centre (BDC). The captured waveform signatures were then analysed using the MATLAB software. The results of the experimental works show that the statistical analysis parameters including the root-mean-square (rms), maximum amplitude and AE energy values are capable of distinguishing the variant of the viscosity. The AE technique can assist the owner of the engine in determining the engine oil's condition before replacing it.

Polymer-plastics Technology and Engineering, 2012

This paper explores the use of active thermography technique for Kenaf-Polyurethane (PU) composit... more This paper explores the use of active thermography technique for Kenaf-Polyurethane (PU) composites. Presently the industry is going toward environmental friendly materials, so investigating more methods in quality control of products is an essential issue. Thermography has potential to detect the defects in-depth. The samples were manufactured by a hand lay-out method and use of a hot press to produce the composites. This method proves that the defects of Kenaf-PU boards are dependent on the amount of fiber and the thickness of the boards. Non-destructive infrared thermography technique has the capability of detecting the defects in Kenaf-PU boards. This study demonstrates evidence that this method can investigate some defects such as voids and kenaf fiber pulled out from its original place with an accuracy of 90%.

Journal of Industrial Engineering and Management, 2008

Polymer-plastics Technology and Engineering, 2011

This article presents the effects of fiber volume fraction on the existence of a transition regio... more This article presents the effects of fiber volume fraction on the existence of a transition region in unidirectional kenaf/epoxy composites. The composites were made from hand Lay-up techniques, with three formulations of fiber volume fraction employed: 0% (neat), 15% and 45%. The results showed that tensile properties such as tensile strength and modulus of elasticity increased as the fiber volume increased. The stress-strain curves showed that the kenaf/epoxy composites exhibited bi-linear responses with reductions in the modulus of elasticity. Surface morphology aided by a scanning electron microscope (SEM) revealed that the reduction in the modulus of elasticity was due to matrix cracking.