B.T.H.T. Baharudin

Recent developments of kenaf fibre reinforced thermoset composites: review

Abstract Kenaf fibres are recently upcoming reinforcement material to be used in composites. This is due to its low density, commercially viability, no health risk, high specific strength and modulus and renewability. It can also be cultivated in a variety of soil and is easily cultivable in some countries. Although traditionally it has been used for products such as rope, twine, bagging and rugs, recently, interests have grown for uses in other applications such as fibre reinforced composites. This paper reviews the recent developments in the use of kenaf fibre as a reinforcement material in thermoset composites. This paper also discusses the multiple types of kenaf fibres itself that are currently available in the market. The processes of kenaf cultivation and pretreatment have also been reviewed. The properties of various kenaf reinforced thermoset polymer composites, interface between kenaf fibre and matrix, and multitude of current manufacturing processes have also been discussed and presented. Recommendations for further research and development have also been given in this paper.

Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm

The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon’s entropy.

Stress analysis of forward aluminium extrusion process using finite element method

Abstract This paper presents the influence of stresses on the nature of the forward extrusion behaviour of aluminium alloy Al-2014, using different die angles (α = 15°, 30°, 90°), and different die bearing length (4, 6, 10 mm). These stresses became high effect towards the die life. It was observed that the high values were created in the contact area between the die and the extruded material. The results showed that, a small die angles required higher extrusion load with 20% more than that of large die angles. In all used die geometry, the deformation of aluminium billet, which is caused by shearing and compression stresses, occurred in a small sectional area (bearing area). The results also showed that, the values of these stresses can either increase or decrease depending on the die entrance angle and the die bearing length. To avoid the effects of these stresses on die dimensions, the hardness, material selection, and geometry should be well calculated. A correlation between the calculated data and FEA was studied in this research by constructing an axisymmetrical 2D geometric (Al) model of the tooling and billet for analysis purpose. The required data, which include: effective stress, strain, material deformation velocity and die-work piece contact pressure were obtained from the finite element (FE) model.

The Influence of Mechanical Mold Vibration on Temperature Distribution and Physical Properties of Al-11.8%Si Matrix Composites

Mechanical vibration was introduced into the Aluminum alloy matrix composite during solidification process. The cooling curves of composite with mechanical vibration were measured and compared without mechanical vibration. The thermal conductivity and thermal diffusivity properties of the Al/TiC composite were investigated. The result indicated that the mechanical vibration reduces the temperature inhomogeneity of melt. The density of the composite with 10.2, 12, 15Hz and 16 Hz of mechanical vibration improved apparently compared with the composite without mechanical vibration. The thermal conductivity and thermal diffusivity properties of composites with mechanical vibration are also both improved significanly.

Enhancement and improvement of the mechanical properties of aluminum extruded products by mathematical analysis and simulation process

This paper investigates a technique for solving the problems of the aluminum extrusion process, and improving the mechanical properties of the products produced by this method through a smart design, simulation and Mathematical Analysis by using F.E.M. For this purpose, the general F.E.A. Software ABAQUS was used to set up the finite element model of the warm aluminum extrusion in two dimensions (3D). Also, an iterative procedure was carried out using MATLAB at each iteration. The model was formulated as a nonlinear model. The inputs to this model were: the product geometry and its materials specifications such as density, rigidity, elasticity, thermal conductivity, and the required analytical steps. An axisymmetrical (3D) geometric model of the tooling and billet was constructed for the analysis. Data obtained from the F.E model included die-work piece contact pressure, effective stress and strain and material deformation velocity. The correlation between the calculated and collected data from (FEA) was ...

Experimental Study of Impact Strength of Al-6063 Alloy Processed by Equal Channel Angular Extrusion

In the present study, the impact strength of annealed Al-6063 alloy developed by equal channel angular extrusion (ECAE), up to 6 passes at a temperature of 200°C following route A with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels was investigated. The impact strength of extruded specimens is evaluated for different passes at a strain rate of 1800 s-1 using Split-Hopkinson pressure bar techniques. The results indicate that the major strength improvement occurs in the 5th and 6th passes while in primary passes, the strength improved but at a considerably lower rate. A total increasing in ultimate strength (UTS) and yield strength (YS) are 127% and 65% respectively and observed for the extruded material after 6 passes. Optical microscopic examinations show a grain refinement from 45 μm to 2.8 μm.

Mechanical Properties of Tin Tailing Sand-Clay Mixture from Batu Gajah, Perak, Malaysia for Making Greensand Casting Mould

Tailing sand from ex-tin mine in Batu Gajah containing between 95.9 to 98.9% silica. In this research involved the process of, conducting the mechanical sieve grading to identify the size spread, plotting the grain size distribution and calculating the average grain size. Further on with the effects of controlled additions of clay (bentonite) and water and determining the working range on the mechanical properties. The investigation involved comparing the mechanical properties of the tailing sand to the requirement for foundry sand applications listed by Foseco Ferrous Foundrymans Handbook (Foseco). Permeability and green compression strength are the important mechanical properties and considered much in the sand casting mould preparation. These mechanical properties play a vital role in determining the allowable clay and moisture content for working range of tailing sand for making green sand casting mould. Experiments for this investigation were conducted according to American Foundrymen Society (AFS) standard of procedures. Cylindrical test pieces dimensioning of Ø50 mm×50 mm in height from various sandwater ratios bonded with 3.8%wt clay and then 7.4%wt clay, were compacted by applying three ramming blows of 6666 g each using Ridsdale-Dietert metric standard rammer. The specimens were tested for green compression strength using Ridsdale-Dietert universal sand strength machine and permeability number with Ridsdale-Dietert permeability meter. Before the tests were conducted, the moisture content was measured using moisture analyser. Tailing sand with allowable moisture content ranging from 3 to 3.5% (bonded with 3.8%wt clay) and 5.5 to 6% (bonded with 7.4%wt clay) were found to have optimum working range with effective green compression strength and permeability.