Current and Past Issues

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Prediction of First Transverse Crack Formation in Cross-Ply CFRP Laminates under Fatigue Loading

Pages 157-164

Atsushi Hosoi, Ken Kurihara, Narumichi Sato, Hiroyuki Kawada

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The formation of a first transverse crack in cross-ply carbon fiber reinforced plastic (CFRP) laminates was predicted under fatigue loading and the fatigue limit of transverse crack initiation was evaluated quantitatively. Transverse cracks induce more serious damage, such as delamination or fiber breakage. It is essential to understand the mechanism of the transverse crack initiation for improving long-term durability of CFRP laminates. Therefore, a method was proposed to predict the number of cycles to transverse crack initiation in cross-ply CFRP laminates under fatigue loading. Two types of cross-ply CFRP laminates, [0/906]s and [02/9012]s, of different thickness were used for fatigue tests. As the results, we were successful in predicting the number of cycles to transverse crack initiation under fatigue loading and evaluating the fatigue limit of the transverse crack initiation by the proposed analysis. Moreover, it was found that the fatigue life to transverse crack initiation in [0/906]s laminate was approximately 50 times longer than that in [02/9012]s laminates.

Keywords: CFRP; transverse crack initiation; fatigue

Evaluation of Mechanical Properties on Rice Husk and Expanded Rice Husk Filled Polyethylene Composites

Pages 165-170

A. Bilal*, R.J.T. Lin, K. Jayaraman, C. Zhang

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Mechanical properties of thermoplastic composites from medium density polyethylene (MDPE) blended with rice husk (RH) or expanded rice husk (ERH) were evaluated in this study. Composites were prepared with particulate fiber loadings of 15, 30, 40 and 50 wt% and with 3 wt% of compatibiliser (maleated polyethylene, MAPE) for each blend. RH and ERH were compounded with MDPE in a twin screw extruder after mechanical mixing of the constituent materials. The composite extrudates were pelletised and injection moulded into test specimens for the evaluation of tensile (strength and modulus), flexural (strength and modulus) and Charpy impact properties according to their respective ASTM standards, ASTM D638, ASTM D790 and ASTM D6110. The results show that with an increase in fiber loading, the tensile and flexural properties of the composites were increased whereas impact strength was decreased. It can be concluded that agro-wastes, such as RH, can be used as filler/reinforcement to efficiently manufacture natural fiber thermoplastic composites for various applications.

Keywords: Rice husk; expanded rice husk; MDPE; rice husk-MDPE composites; mechanical properties

Finite Element Analysis of Underground Storage Tank Subjected to External Loadings

Pages 171-178

Si-Chung Jong, Kim Yeow Tshai

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The geometry of underground storage tank (UST) generally ranges from 1.2 - 3.7m in diameter and 1.8 – 22 m in length. The features and thickness of UST must be designed to withstand external loadings and weight of its fluid content. Once installed with all piping fixed, on-site measurement becomes a major challenge and performance monitoring data are scarcely available. Finite element analysis (FEA) on the other hand provides a rapid and reliable route to predict the effects of complex loadings on deformation stress and strain behaviour of solid structure. In this paper, 3D computer aided design (CAD) of a full-scale, half-symmetry, UST model is analysed within two FEA programs, namely ANSYS and ABAQUS. The underground environment is converted into boundary inputs and a chopped-strand-mat composite UST is subjected to a series of coupled static structural loadings. The simulated deformation and vonMises stress are obtained to evaluate the most destructing conditions. Two series of analyses were performed, with and without restraining rope. The results provide an insight into the behaviour of UST system subjected to a predefined set of prescribed loadings. From the perspective of these FEA packages, the simulation and analytical data broadly agreed among one another.

Keywords: Underground storage tank; finite element analysis; chopped strand mat

The Effect of Cladding Parameters on Microstructure and Microhardness of 308L Stainless Steel Single Bead Clad Deposited on Cast Iron Using Gas Metal Arc Heat Source

Pages 179-185

N.I.S. Hussein*, N.F. Asri, S.R. Shamsuri

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Cladding using gas metal arc welding (GMAW) as a heat source is to enhance material surface properties from corrosion and wear resistance, in addition to repairing the damage part by depositing it with stainless steel molten wire layer-by-layer to cover the required area. The main aim of this study is to investigate the effect of cladding parameters on the microstructure and microhardness properties of stainless steel single bead clad deposited on mild steel substrate. The deposited single bead clad was characterized by using optical microscope and Vickers microhardness testing. The single bead clad is crucial to be studied before single layer of multitrack clad with desired overlap ratio are carried out. This is to understand the propertiesrelationship occurred during and after the process. The experimental study on the single bead clad was designed using response surface methodology (RSM). This study has found that crack free structure of 308L SS wire can be deposited on carbon steel substrate and the clad dimensions as well as microhardness were influenced by the arc voltage, arc current and traverse speed.

Keywords: Cladding stainless steel; gas metal arc welding; microstructure and microhardness behavior

Mechanical and Physical Properties of Kenaf-Acacia Auriculiformis Particleboard Composite

Pages 186-193

J.W. Wong, W. S. Yeo, M. Faizal, S. Hashim

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The influence of various mixing ratios by weight percent of kenaf and acacia (0:100, 10:90, 30:70, 50:50 and 100:0) on the mechanical and physical properties of the particleboard was investigated. The particleboard was produced by compressive moulding at a temperature of 164 ˚C, pressure of 30kg/m2 and pressing time of 6 minutes. The properties such as modulus of elasticity (MOE), modulus of rupture (MOR), thickness swelling (TS), water absorption (WA), and internal bonding (IB) were determined. The results showed that particleboard with 100% kenaf particleboard gave the highest MOE and MOR which are 2098.16 MPa and 12.46 MPa respectively. However, the properties of MOE and MOR declined when the content of acacia increased. On the other hand, particleboard consisted of 100% acacia showed the lowest percentage change in TS and WA with only 8.82% and 61.35% respectively. The non-porous structure of the acacia contributed to this observation. Furthermore, the results showed high IB of 0.291 MPa was obtained from particleboard consisted of 50% kenaf. In addition, the weight ratio of kenaf: acacia at 50:50 and 30:70 particleboards gave the best mechanical properties. Therefore, it is concluded that the particleboard with minimum 30% kenaf met the requirement by British Standard (BS EN 312:2003), for general purpose.

Keywords: Kenaf; acacia auriculiformis; particleboard

Application of EPRI P87 in Dissimilar Austenitic-Martensitic Welded Joints of TEMPALOY A-3 and T91

Pages 194-203

Michael Urzynicok*, Robert Jachym, Krzysztof Kwieciński, Paola Mariani,Yusuke Minami

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The primary objective of this research was to check the welding properties of high oxidation resistant superheater steel TEMPALOY A-3 welded to simulated header stud of grade T91 using EPRI P87 filer metal. After welding and heat treatment all required non-destructive tests and mechanical examinations were done. The results obtained show very good mechanical properties of welded joint and additionally the transition zone between weld metal of EPRI P87 and martensitic material is very narrow compared to well-known Inconel 82 while micro-hardness tests shows regular values for EPRI P87 and reveal a soft-zone in Inconel 82 filer. Further creep tests of EPRI P87 will show long term properties in high temperatures compared to Inconel 82 and Inconel 617. On joints made by INCONEL 82 filler metal, the mechanical and plastic properties achieved were higher than those obtained on material welded by EPRI P87.

Keywords: TEMPALOY A-3; EPRI P87; dissimilar welding

Synthesis of Precipitated Calcium Carbonate from Industrial Waste Carbide Lime by Using Sucrose as Promoter

Pages 204-210

S. Dzuhri1, N. Y. Yuhana, O. Anuar, I. Nasharudin, O. Rohaya

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The production of precipitated calcium carbonate (PCC) using sucrose solution with Brix reading of 11º is presented in this study. A low-grade Carbide lime obtained from industrial waste as the raw material was used in the carbonation process. The experiments were performed by varying the amount of calcium hydroxide (Ca(OH)2) in sucrose solution of 11°Brix. The amount of PCC obtained was higher by using sucrose solution compared to nonsucrose solution. This can be due to the higher solubility of Ca(OH)2 in sucrose solution. The morphology of calcium carbonate obtained was in calcite form with some shapes of cubic, spherical, and coral. The use of low amount of Ca(OH)2 formed PCC with cubic structure. However, at high amount of Ca(OH)2, button and spherical shapes were observed.

Keywords: Calcium carbonate; calcium hydroxide; sucrose; precipitated calcium carbonate; carbide lime; carbonation