Mohd Noor Mazlee

FAILURE ANALYSIS OF CRANE WIRE ROPE

A failure analysis of a broken multi strand wire rope from an offshore platform crane was performed. The wire rope was operated for less than 5 years. The wire consists of seven strands, one central strand and six strands around it. The diameter of the small wires was about 0.78-0.94 mm and the larger wires was a round of 1.52 - 1.78 mm. The large size wires were found fractured by cyclic torsional stresses as characterized by the presence of fatigue cracking originating from the outer surface of the wire. Meanwhile the smaller wires were fractured in a ductile manner under excessive load after the larger wire broken out due to the fatigue mechanism.

The Development and Characterisation of Porous Clay - Precipitated Calcium Carbonate

Ceramic foams, a porous material with a gyroid structures, are becoming highly demanded for various applications such as heat insulation, bone implantation and filtration, because of their unique properties such as high specific surface area, high porosity and low heat transfer rate. In this study, the development of ceramic foam utilised white clay with a combination of precipitated calcium carbonate (PCC). The ceramic foam was successfully developed using this combination after the sample was sintered at 1250 °C for 2 hours holding time. The various compositions of PCC (10.0, 12.5, 15.0, 17.5, 20.0, 22.5 and 25.0 wt.%) affected the chemical composition and compressive strength of the ceramic foam. The chemical composition of ceramic foam was analysed by using X -ray fluorescence (XRF) and the result indicated that the PCC was successfully transformed into calcium oxide (CaO) after the sintering process. The mineralogical composition of the ceramic foam was evaluated using X-ray diffraction (XRD) and has shown the presence of mullite (3Al2O3.2SiO2), gehlenite (Ca2Al2SiO7) and anorthite (2CaAl2Si2O8) after the sintering process. The scanning electron microscope (SEM) analysis showed that the presence of porosity on the strut of the ceramic foam. Meanwhile, the compressive strength of the ceramic foam increased from 0.03 to 1.31 MPa, which is directly proportional to the increased amount of PCC.

Porous Solid Carbon Dioxide Adsorbent Using Cost Effective Materials: A Review

Greenhouse effects were generated from anthropogenic emissions of carbon dioxide (CO2) into the atmosphere. High concentration of CO2 has recognised as major causes of global warming. In order to keep CO2 at a manageable level, adsorptions of these gases from the flue gases is necessary. Developing a low cost porous solid adsorbent as adsorption media become a great attention due to environmental and economic concerns. This paper has reviewed the cost effective materials with a suitable methods to fabricate the porous solid adsorbent. This paper also has discussed the adsorption mechanisms of CO2 on the selective cost effective materials.

Static X-Ray Scans on the Titanium Hydride (TiH2) Powder during Dehydrogenation

This work investigates the dehydrogenation of TiH2 powder during isothermal heating at 600°C using the static x-ray scans of high temperature x-ray diffraction (XRD). As-received TiH2 powder with a particle size of 5 μm and purity of 99.1% was used for this measurement. With increasing temperature, phase transformations occurred because of dehydrogenation and it happened very fast. It was found that during the phase transformation of TiH2 to titanium, some transitional phases observed and occurred. This finding confirmed the in-situ determination of TiH2 powder dehydrogenation by using Rietveld Refinement Method from our previous research. This study is useful for the fabrication of titanium-based composites and titanium alloys from TiH2 powder because the different phases in TiH2 will affect the final mechanical properties in titanium.

Failure investigation on rusty mesh strainer of petrochemical plant

The wire material of filter mesh is made of 304 grade stainless steel. The failure to run properly was due to the impact of burst and torn. The client also expects that the failure was due to corrosion problems. A visual inspection on the strainer mesh was found covered by brownish rust layers and some scratches at the damaged area. The rusty wire mesh that was washed with pickling acid showed a clean and smooth surface. Energy dispersive spectroscopy (EDS) examination of the rusty wire mesh surface indicated that it was only normal oxide precipitates. Thus, its proven that there were no signs of severe corrosion attack on the failed sample. SEM micrographs showed the unidirectional scratch effects exist in the damaged area. The fractography study was found there was a typical ductile structure on the fracture surface of the wire. It is proven that the wire mesh was actually still in good condition and has not experienced any embrittlement problems as if it exposed to any corrosive environment. The root cause of the failure is shown by the effect of scratches in which it is usually caused by a mechanical forceful push by a hard object or in other words, it is caused by human error factor.

Effects of Fly Ash Addition on Compressive Strength and Flexural Strength of Foamed Cement Composites

In this study, the mixing of polystyrene (PS) beads and fly ash as a sand replacement material in foamed cement composites (FCC) has been investigated. Specifically, the mechanical properties such as compressive strength and flexural strength were measured. Different proportions of fly ash were added in cement composites to replace the sand proportion at 3 wt. %, 6 wt. %, 9 wt. % and 12 wt. % respectively. The water to cement ratio was fixed at 0.65 meanwhile ratios of PS beads used was 0.25 volume percent of samples as a foaming agent. All samples at different mixed were cured at 7 and 28 days respectively. Based on the results of compressive strength, it was found that the compressive strength was increased with the increasing addition of fly ash. Meanwhile, flexural strength was decreased with the increasing addition of fly ash up to 9 wt. %. The foamed cement composites with 12 wt. % of fly ash produced the highest strength of compressive strength meanwhile 3 wt. % of fly ash produced the highest strength of flexural strength.

Influence of Tool Plunge Depth on the Joint Strength and Hardness of Friction Stir Welded AA6061 and Mild Steel

The purpose of this paper is to investigate the impact of the tool plunge depth on the mechanical properties of friction stir welding (FSW) of AA6061 and mild steel. In FSW, welding is performed using a non-consumable rotating tool that is allowed to plunge in between two plates in a butt joint and travel along the abutting line. The tool plunge depth determines how deep the pin and shoulder of the tool penetrates the surface of the plates. Tensile testing was performed to determine the influence of plunge depth at different tool travel speeds on joint failure strength. Also, the formation of defects and its relationship with plunge depth were also investigated. Vickers microhardness testing was also done on weld cross sections to study plunge depth’s effect on hardness.

Tensile and Hardness Analysis of Dissimilar Friction Stir Welding Between AA6061 with AA5083 and Mild Steel

In this paper, the friction stir welding (FSW) technique was used to create dissimilar alloy joints of AA6061-AA5083, and dissimilar material joints of AA6061-S235JR mild steel. Joints were fabricated by a conventional belting milling machine. Plates of 5 mm thickness were welded in a butt joint configuration. The joints were evaluated by extracting tensile testing specimens to study the failure strength at different rotational speeds. Tunnel defects were formed under certain parameters and changing the parameter values had different effects on the tunnel defects depending on the type of dissimilar joint welded. Vickers micro hardness measurements were taken on cross sections of welded joints to study the hardness pattern across the weld zones.

Variation of Tool Offsets and Its Influence on Mechanical Properties of Dissimilar Friction Stir Welding of Aluminum Alloy 6061 and S235JR Mild Steel by Conventional Belting Milling Machine

The tool offset parameter’s influence on joint strength of friction stir welding (FSW) of aluminum alloy 6061 and S235JR steel performed on a conventional belting milling machine was evaluated. The type of welding defects that arose at different tool offset values and how they affect the ultimate tensile strength (UTS) of the joints produced are also studied. It was found that at +0.2 and 0 mm offset, welding was incomplete and tunnel defects were formed, with average tensile strengths of 22.91 and 41.62 MPa for joints welded at each tool offset values respectively. Tool offset value of −0.2 mm was found to produce the best joints in terms of tensile strength, at an average of 95.73 MPa. For all joints, in terms of defects it was found that incomplete welding severely reduced tensile strength of joints, while tunnel defects also deteriorated tensile strength of joints albeit to a lesser degree.

Mechanical properties of friction stir welded butt joint of steel/aluminium alloys: effect of tool geometry

This paper described the mechanical properties from hardness testing and tensile testing of Friction Stir Welded (FSW) materials. In this project, two materials of aluminium and steel are welded using conventional milling machine and tool designed with different profile and shoulder size. During welding the temperature along the weld line is collected using thermocouples. Threaded pins was found to produce stronger joints than cylindrical pins. 20 mm diameter shoulder tool welded a slightly stronger joint than 18 mm diameter one, as well as softer nugget zone due to higher heat input. Threaded pins also contributed to higher weld temperature than cylindrical pins due to increase in pin contact surface. Generally, higher temperatures were recorded in aluminium side due to pin offset away from steel.