Advanced Materials Research Vol. 789

Abstract: Thin wall ductile iron (TWDI) is introduced to fulfill the needs of lighter material in automotive parts that will reduce fuel consumption. Problem occurs during the production of TWDI due to the casting thickness. TWDI casting thickness classified to below 5 mm. Many designs have been made to answer the problem in producing thin wall ductile iron. Soedarsono et al established vertical step block casting design. This design based on Y-block principle that allows direct pouring of liquid metal to the mold without passing any gating system. This design will increase casting yield. The parameter of this research is pouring basin placement to study the effect of plate arrangement to filling and solidification. This research is conducted to see the effect of pouring basin placement to microstructure and mechanical properties of TWDI. The Design is made to produce 5 plates with different thickness that is 1, 2, 3, 4, and 5 mm. All of the plates arranged parallel in line. Pouring basin located in 2 ways. The first type located pouring basin above the plate of 5 mm thickness while the second one located it above the plate with 1 mm thickness. The first type coded as T4 while the second coded as T5. The moulds made from furan sand. The result shows although cold shut occurred in both pouring basin placements due to pouring discontinuity but shrinkage only formed in T5 on its plate with 1 mm thickness. Microstructure of all the plates presented nodule graphite in pearlite matrix. Carbide and skin effects also detected. Average nodularity is above 80% while the nodule count is between 614 to 1269 nodule/mm². Most of the Brinell hardness number exceeded maximum limit given by JIS G5502 but the UTS is below the minimum limit except for 3 mm plate thickness of T5. All elongation values below the minimum standard. The results confirm that pouring basin location is important in casting design following Y-Block principle.

Abstract: This work concentrates on assessment of the TEP change of AA6061 during isothermal aging at 177 °C and the following interrupted aging at 65 °C. The results show that the TEP is sensitive to follow the microstructural changes undergone during all aging stages. Multiple sub-ambient temperature dependences TEP of binary Al-X alloys as well as the AA6061 subjected to the above mentioned heat treatments were undertaken. The solute level of individual element of the alloy, particularly those contributing to the clustering/precipitation, can be extracted and evaluated.

Abstract: In this research, it has been carried out the development of a strength analytical method of a thin-walled steel square pipe (Square Hollow Section/SHS) affected by the interaction of concentrated-compressive load and bending moment then it verified by experimental approach. The experimental approach was consisted of measuring a basic material property and the strength of the investigated SHS pipe. The basic material property identified parallel to rolling direction (0^o) and perpendicular to rolling direction (90^o). The analytical data obtained from cut-off strength method is generally scattered within the acceptable limits of ± 20 % and tends to be in unconservative region. The actual data measured from experiments shows that SHS beam with t = 0.6 mm and longitudinal axis parallel to the rolling direction of base material has higher strength compared to the one of the SHS beam with t= 0.6 mm and longitudinal axis perpendicular to the rolling direction, meanwhile the SHS beam with t= 1.2 mm is tends to be equal. This means that the rolling direction of base material can be considered to be a parameter in the strength design of a thin-walled SHS beam

Abstract: Utilization of wind power in Indonesia is less attractive compared with utilization of conventional fuel. This is because the price of wind energy is not competitive when compared with fossil energy prices, and as a result of the implementation of energy pricing policy through subsidies. Before designing the Wind Energy Conversion System, simulation of computational fluid dynamics needs to be done in order for reducing designing time and cost. In this research, modeling and simulation work has been done to figure out the optimum aerodynamics coefficient of wind turbine blades at different Reynolds number. This blade is a modification of standard airfoil of NACA 4415. The aerodynamics coefficient of modify and standard airfoil is then compared. FLUENT software and Spalart-Allmaras Turbulent Model are used in this work. Based on the comparison of the coefficient of aerodynamic, modification NACA 4415 airfoil has better performance at Reynolds number of 4.1 x 10⁴ to 2.5 x 10⁵. The experiment results also showed that based on a numerical study of the modification NACA 4415 airfoil can be used as a basis for the establishment of wind turbine blades.

Abstract: Several studies have demonstrated the ability of laser for micro-channels fabrication. There are some important aspects that must be considered to use laser for machining process, such as machining method, type of laser and interaction between laser and workpiece. In this research, CO2 laser machine was used as a tool to fabricate a micro-channes on acrylic. Some parameters that can influence the outcome of the cuts were setup, which are focus distance on Z axis, laser power, cutting speed, and the repetition of cutting process (number of pass). Cutting results were width and depth of cut. Observation was made by using digital microscope as measuring tool, and measurement result was analyzed by using Anova method. The results of the analysis shows that the parameter of laser power has a dominant influence on depth of cut, and then parameter of cutting speed and number of pass. By determining width and depth of the cut based on given parameters, it will be easier to take a shape and size on micro-channel fabrication.

Abstract: To improve production efficiency and quality of fiber-glass boatyards many research have been done both through technological as well as management aspects. One of these developments is Vacuum Assisted Resin Transfer Molding (VARTM) which is claimed to have high strength and material efficiency. This method has not much been applied in Indonesian boatyards, most of them are still using conventional hand lay-up. The research is aimed to investigate the strength of the composite and the optimum amount of materials to obtain the required strength for its application on boat buildings. Experimental approach was conducted in the research using 800 biaxial and 900 unidirectional E-glass for reinforcement, and vinylester (RIPOXY R-802-EX-1) resin for the matrix. The ultimate tensile strength and Youngs modulus of the composites are obtained through tensile and flexural test based on ASTM D 3039 and ASTM D 790 standards. The data obtained are used to determine the optimum number of layers and fiber content on certain locations of the boat hull structure in order to comply with the requirements of classification rules.

Abstract: The screw propeller of a ship generates thrust to make it moving. As a propeller rotates, it draws fluid into itself from the surrounding area (slipstream). The propeller produces two types of flow behind it, accelerated and circulated flows. Some of the energy from the ship engine is lost in the accelerated flow behind ship as a jet wash.The kinetic energy losses in the slipstream propeller captured by a turbine called the propeller-turbine system. This composed screw propeller of a vessel (the main propeller) and a vane turbine that is the area of vanes located inside the wake of the main propeller. It recovers the energy generated by the main propeller pushing water back out (which would be otherwise wasted behind the main propeller) and hopefully enhancing the efficiency of the main propeller.The influence of vane turbine on the performance breakdown of single screw ships were analyzed by using 5 (five) ships . Ship powering was calculated by using DESP Code 10 software. Thrust and power of vane turbine were calculated by applying actuator disc theory. Although the vane turbine affected speed loss of the ship, the power efficiency gained to be found always positive. Vane turbine is suitable as an energy saving device of the single screw ship.

Abstract: The development of electronic devices pushes manufacturers to create smaller microchips with higher performance than ever before. Microchip with higher working load produces more heat. This leads to the need of cooling system that able to dissipate high heat flux. Vapor chamber is one of highly effective heat spreading device. Its ability to dissipate high heat flux density in limited space made it potential for electronic cooling application, like Central Processing Unit (CPU) cooling system. The purpose of this paper is to study the application of Al₂O₃ Nanofluid as working fluid for vapor chamber. Vapor chamber performance was measured in real CPU working condition. Al₂O₃ Nanofluid with concentration of 0.1%, 0.3%, 0.5%, 1%, 2% and 3% as working fluid of the vapor chamber were tested and compared with its base fluid, water. Al₂O₃ nanofluid shows better thermal performance than its base fluid due to the interaction of particle enhancing the thermal conductivity. The result showed that the effect of working fluid is significant to the performance of vapor chamber at high heat load, and the application of Al₂O₃ nanofluid as working fluid would enhance thermal performance of vapor chamber, compared to other conventional working fluid being used before.

Abstract: Dieless bellows forming using local heating technique is an advanced flexible forming technology to produce bellows from straight tube without the use of dies. The deformation is induced by applying continuous compression, and local heating. Advantages of these processes are the absence of dies, applicability for various materials, suitability for flexible forming process including low batch production, flexibility on workpiece sizes and output geometries. However, the implementation of these processes is still low owing to the low quality, reproducibility, and production speed. The limitation of these dieless forming processes using local heating is caused by the absence of dies required to form the desired profile. Therefore deformation depends on temperature, length of heating zone, processing speed, speed ratio of feeding to fabrication speeds. In order to enhance the product quality in these dieless forming with local heating, real-time monitoring are necessary to identify deformation progress. Machine vision based on image processing technique was selected to monitor deformation behavior on dieless bellows forming process. The present paper describes real-time monitoring using image processing approach to monitor dimensional profile and temperature distribution during the process. The results show that machine vision is effective and efficient to monitor dynamic deformation of dieless bellows forming proces and able to identify abnormal process condition.

Abstract: Numerical simulation by finite element method has become a powerful tool in predicting and preventing the unwanted effects of sheet metals technological processing. One of the most important problems in sheet metal forming is the compensation of springback. To improve the accuracy of the formed parts, the die surfaces are required to be optimized so that after springback the geometry falls at the expected shape. This paper presents and discusses numerical simulation procedure of die compensation by using the methods of Simplified Displacement Adjustment (SDA). This analysis use Benchmark 3 models of Numisheet 2011. Sensitively analysis was done by using finite element method (FEM) show that the springback values are influenced by element size, integration points and material properties.