Applied Mechanics and Materials Vol. 315

Abstract: Surface topography plays an important part in understanding the nature of machined surfaces. This study is focused on surface topography of AISI D2 hardened steel (58-62 HRC) under dry milling process. Roughness, surface morphology and defects analysis were investigated. This study achieved R_a in range of 0.18 to 0.30 µm which is acceptable in mould and die requirement. Moreover, surface roughness decreased as cutting speed increased. From the optical microscope observation shows that the milled surface is anisotropic in nature. The lay pattern is produced by the combination of tool movement during milling operation (cutting and feed speed directions). Meanwhile, the AFM images indicated that the milled surfaces are groovy constructed by low-amplitude topography (between peak and valley of the machined surface waves). Surface defects were found in this study were debris, groove and cavity, all of which affected the surface roughness value.

Abstract: Solid cylindrical bars have tremendous applications in mechanical engineering. However due to several factors such as corrosion, material and design defects, mechanical failure is unavoidable. In the present of mechanical loadings, the crack initiated at such defects and growth. Therefore, this work focuses on a numerical simulation to analyze the behavior of the surface cracks under combined mode-I loadings. Different crack aspect ratios, a/b and relative crack depth, a/D are used and the plastic stress/strain is assumed to follow the Ramberg-Osgood relation. Then, the limit loads were combined with a reference stress method to develop a mathematical model to predict J-integral along the crack front. Referring to the results, the J-integral can be predicted along the crack fronts. However, the capabilities to predict J-integral are reduced when a/b and a/D is increased.

Abstract: The interest in utilizing natural fiber as reinforce in polymer composites has increased in recent years due to their advantages like availability, cheap, renewable, lightweight, and biodegradable. However, the main challenge of natural fiber to be used as reinforcement in polymer is their hydrophobic nature. One of the solutions is via chemical modification like mercerization treatment. In this study, the effect of alkali concentrations at 2 and 10 w/v %; and soaking temperature at 30°C and 80°C on a kenaf fiber bundles mean diameter was investigated. Untreated kenaf fiber was used as a control unit. Kenaf fiber diameter was measured using a Leica video analyzer. Microstructure change of kenaf fiber before and after mercerization treatment conditions was identified using JOEL scanning electron microscopy (SEM). Finally, an interaction of alkali treatment conditions on kenaf fiber bundles mean diameter value was statistically analyzed using a commercially available statistical software package. The results showed that kenaf fiber bundle mean diameter was reduced by 30.12% to 42.92% after mercerization treatment. From analysis of variance, the main effect of alkali concentration value was 6.075 and the temperature value was 1.135. The main effect plots reveal that alkali concentration had a higher impact on mean diameter changes compared to soaking temperature factor.

Abstract: This work presents the studies of wettability Sn-6Zn-4Bi lead-free solder alloy in electronic applications. A reference solder Sn-3.1Ag-0.9 Cu lead-free solder alloy is used to compare the properties of both solders. Differential Scanning Calorimeter (DSC) profile, wettability and the microstructure of the solder were investigated. The melting temperature of Sn-Zn-Bi (Tm=194.97°C) is lower than Sn-Ag-Cu (Tm=220.40°C). Further, the wettability between molten solder and copper substrate was measured at different reflow temperature. The contact angle for Sn-Ag-Cu was decreasing from 28.23º to 24.97º and for Sn-Zn-Bi solder alloys were decreasing from 48.92º to 29.78º as the temperature increased from 230°C to 250°C. A significant increment of contact angle for Sn-Zn-Bi at 270°C and the contact angle did not change at 270°C for Sn-Ag-Cu. The result of spreading area is inversed with the contact angle. The layers of intermetallic compound were examined by energy-dispersive X-ray. The Sn-Zn-Bi solder exhibits a mixture of Cu-Sn+Cu-Zn phase and ϒ-Cu₅Zn₈ phase. The Sn-Ag-Cu solder exhibits Cu6Sn5 (η-phase) and Cu3Sn (ε-phase). As a conclusion, Sn-Zn-Bi is a potential lead-free solder to develop based on its wettability properties than previous available solder materials.

Abstract: Rotor unbalance and shaft misalignment are common major concerns in rotating system. In this study, vibration analysis for unbalanced rotor and misaligned shaft components using non-contact laser Doppler vibrometer (LDV) were examined. The vibration acceleration magnitude (m/s²) and FFT spectrum from the both fault detections were recorded by the portable laser Doppler vibrometer and analysed by the vibration analysis software. The result shows that combination of unbalance and parallel misalignment fault conditions can produce higher vibration thus reduce the life span of the rotor system. In this case, the unbalance fault condition combined with parallel misaligned rotor gave highest vibration magnitude followed by simply unbalanced rotor and parallel misalignment fault only. This experiment shows that the non-contact method has successfully detected the unbalance and parallel misalignment fault in the rotor system.

Abstract: Due to global competition, automotive component industries are very keen to improve their manufacturing system as to fulfill car manufacturer demand. Currently, lean manufacturing (LM) system has become increasingly famous and popular among automotive component players. And, it was proven that lean manufacturing is the best manufacturing system in the 21^st century. The main objective of this paper is to investigate the extent of 24 lean manufacturing practices implementation in SME. Secondly, to determine the possible barriers that could influence the process of lean manufacturing implementation. A survey questionnaire was developed to collect top and senior management judgement on 24 lean manufacturing practices and to rate the possible barriers during lean manufacturing implementation. Total completed questionnaires were 97 which represent 81.5% respond rate. The survey results show that a majority of respondents agreed and implementing extensively kaizen, 5S and standardization in their firms. Another finding was the four possible barriers that could influence the failure of lean manufacturing implementation which are employees resist to changes, unstable customer schedule, lack of knowledge and poor employee involvement.

Abstract: This research is done to explore the advantage of ultrasonic clamp on tubular reactor as a new technology for the transesterification process of the vegetable oil by using the newly fabricated small biodiesel pilot plant. The following studies will analyze on the performance and the efficiency of the ultrasonic tubular reactor in its flow performance and the influence of the angle towards the flow rate which plays the role in the production. The low flow rate and reaction time will influence the cost of biodiesel process and by using ultrasonic, it helps the chemical reaction process to react faster hence contributing to less time consumption. In the research, the methanol to oil molar ratio will consists of 6:1, 9:1 and 12:1 respectively. Besides that, the percentage of catalyst concentration is 0.75 %, 1% and 1.25%. The fabricated small biodiesel pilot plant will be a part of knowledge on biodiesel process and its production.

Abstract: The portable petrol driven oil palm motorised cutter or CANTAS has been identified as a type of machine that generates hand-arm vibration. These vibrations can cause complex vascular, neurological and musculoskeletal disorder known as hand-arm vibration syndrome (HAVS) when over exposure of daily usage. The objective of this study is to investigate the vibration level at different angles during the operational of the CANTAS including idle and full throttle conditions. The CANTAS vibration experiments were carried out at a farm in Parit Raja, Batu Pahat, Johor. A student participated as the unskilled worker and was assisted by two technical staffs to conduct the vibration measurements. The measurement was taken during the operations of cutting first fronds, second fronds and a fruit bunch during idle and full throttle conditions and by varying the inclination angle. The inclinations of cutting angle were varied from 45º, 60º and 75º. The hand-arm vibration value, a_hv achieved 10.93 ±1.2 m/s² and 7.94 ± 1.0 m/s² for unskilled user during operation of two bunches and one pruning frond for all angles at point 1 and point 2 handle respectively. Mean vibration values at both point of handles resulted in vibration values of 10.12±3.8m/s² at 45⁰, 9.15±3.0m/s² at 60⁰ and 9.03±1.8m/s² at 75⁰. Increasing the angle overall results in decreasing the level of vibration at both handle points.

Abstract: Commercially pure (cp) titanium is a relative soft metal and easily broken on friction-wear applications. To improve the hardness of the surface while maintaining the original properties, plasma nitrocarburizing process has been conducted. The effects of the treatment in different temperatures to the surface harness are then studied. In this study, cp titanium plasma nitrocarburizing process is conducted at different temperatures with different process time, i.e. at 350 °C for 3, 4, and 5 hours, and at 450 °C for 2, 3, and 4 hours respectively. Hardness tests are then performed on each specimen by using Micro Vickers Hardness Tester. The hardness values for the plasma specimens nitrocarburizing processes at temperature of 350 °C for process duration of 3 hours, 4 hours, and 5 hours are 74.16 HV, 92.25 HV and 94.41 HV, respectively, while for processes at temperature of 450 °C, the hardness values are 103.70 HV, 121.31 HV, and 126.17 HV for process duration of 2 hours, 3 hours, and 4 hours respectively. Hardness value of specimens which are resulted from the plasma nitrocarburizing process at temperature of 450 °C is higher compared with specimens that are processed at temperature of 350 °C.

Abstract: This paper aims to provide an insight to later researchers on the application of axiomatic design in the area of design for end-of-life (EOL) management. Among all life cycle stages of a product, design and development stage is the one that influences the later stages the most in terms of environmental impacts. In order to achieve sustainable product development, one of the considerations to be taken during the design stage is EOL management. EOL management process can be enhanced by utilizing a robust design method as well as an effective method for evaluating product design. Recent researches show that application of axiomatic design in the field of eco-design (especially design for EOL management) is still in a premature stage despite having a vast application area that covers the aspect of product design, manufacturing and supply chain management. Nonetheless, a case study published recently on eco-design using axiomatic approach has shown adequate feasibility and effectiveness. Therefore, design for sustainable EOL using axiomatic approach is worth further exploration.