Applied Mechanics and Materials Vol. 493

Abstract: Stiffened sheet metal structure where sheet metal is reinforced by frame has been claimed as the most effective structure because it has low volume and weight. It is generally applied to large car body structure such as bus and train body. Frame and sheet are commonly joined by welding process. Due to the local heating of welding, distortion or deformation will occur in this structure. To mitigate this distortion, new method called stretching technology was proposed in this work. In this method, sheet was stretched to certain pre-strain, kept in this condition and then welded to frame. Special equipment powered by hidroulic system was designed to support this method. Low carbon steel SPAC specimens with dimension of 400mm, 1824mm and 3mm in width, length and thick respectively were prepared to evaluate the method. Hidroulic power was controlled to meet the sheet pre-strain variations of 0.00%, 0.05%, 0.10% and 0.15%. The distortion of the specimen was measured by dial indicator with mesh point of 50mm and shown in 2D contour chart. The study results revealed that the welding process on the sheet without pre-strain had the highest distortion of 8.34mm while that with pre-strain of 0.05% provided the lowest distortion of 3,3mm or 60% lower than without pre-strain specimen. The pre-strain of 0.10% and 0.15% produced the sheet distortion of 7.05mm and 7.9mm respectively. The excessive pre-strain was an ineffective method to mitigate the welding distortion because the reverse tension force of sheet would destroy the weld joint when the hydraulic force was released.

Abstract: The surface quality generated when high speed dry end milling (HSDEM) Ti-6Al-4V-ELI titanium alloy with coated and uncoated carbide tools were investigated. Evaluation was conducted using TiAlN+TiN coated and uncoated cemented carbide tools under different high cutting speeds and feed rates conditions. Surface roughness and cutting forces were measured when using new tools. The milled surface quality and corresponding alteration were characterized through electron microscopy. Within the investigated conditions high quality surface finish was obtained on the machined surface. Increasing cutting speed from 200 to 300 m/min during the process improved the surface finished particularly under lower feed rates. In term of generated surface quality, uncoated H25 grade carbide tools out performed coated F40M grade specifically at the higher cutting conditions. The main damages observed after HSDEM on the surface for all machining conditions contain redeposited materials, feed marks, and tool edge marks. Under both tested feed rates the resultant cutting force decreased by increasing the cutting speeds and uncoated carbide tools provide the lower cutting forces compared to coated types.

Abstract: Maskless photolithograpy is an alternative method of conventional UV photolithograpy for microfabrication since its advantages of time and cost saving. For this reason, a visible-light based maskless photolithograpy is proposed as a part of biomachining process. Modification of the method is done by replacing light source of UV light to visible light, utilizing commercial DLP projector and changing the material removal process that generally uses echant with biomachining process. The process was done by using the profile generated by computer then displayed through a commercial DLP projector shining speciment test. Focusing lens placed under the projector to draw the focal point and reduces the size of the profile. The best parameter was determined by setring exposure time, developing time, variation profiles, focusing, colors combination and optical aspect. Using a commercial projector maskless photolithography on a negative resist tone successfully performed. The best characteristic was obtained by placing the focusing lens 3X magnification within 3 cm below the projector and 14 cm above speciment test, color combination of black-light blue (R = 0, G = 176, B = 240), with the timing of prebake 1 minute, exposure 7 minutes, postbake 5 minutes, developing 5 minutes produces the smallest profile 166 μm with 13,7 μm deviation. Biomachining process with bacteria Acidithiobacillus ferrooxidans NBRC 14262 on copper was also successfully performed with the smallest profile of 180 μm with 26 μm deviation.

Abstract: Tungsten Inert Gas (TIG) welding is a process which an electric arc generated by the tungsten electrode to the workpiece and the welding area protected by a protective gas. Arc shape can be affected by electromagnetic force. In previous study, the use of some electromagnetic field around the arc has influenced the welding results. In this study, electromagnetic field generated from the solenoids was given to the welding arc. Welding process was conducted on Stainless Steel. The electromagnetic field made the arc becomes deflected. This deflection was controlled by the solenoid by activating it using a microcontroller. The results showed that the use of solenoid as a source of electromagnetic field has influenced the welding arc. Penetration produced by using a solenoid has deeper penetration than welding process without using solenoid. The increase of the welding power efficiency was 10.9% for arc current I = 80 A and 9.85% for arc current I = 90 A.

Abstract: Gripper is mechanism that mounted on the end of the robot arm and used to hold an object and move it to a certain position. Generally, classical gripper is equipped with the driving motor (electric, pneumatic, fluid power) to move the gripper mechanism. In this research, the function of driving motor replaced with gripper motor actuators made of Shape Memory Alloys (SMA) of Nickel Titanium (NiTi) wire type SM495. Problem studied is response of grip force of gripper to varied electrics power input that given to the actuator of gripper made of NiTi SM495 wire. This is a real experimental research using parameters electrical power input which is obtained by varying the applied electric voltage 3, 6, 9, 12 Volt and constant electric current 5 A. Linear springs with various springs constants of 0.14 N/mm; 0.49 N/mm; 0.981 N/mm; 1.308 N /mm were used for measuring grip force of gripper. The obtained data then analyzed using statistics (analysis of variance). The results showed that the electrical power which given to the NiTi based actuator significantly influenced the grip force of gripper. Keywords: actuators, electric power, grip force, gripper, Nickel Titanium, Shape Memory Alloys, SM495 wire

Abstract: Recently, many studies have been done to look for renewable energy sources such as kinetic energy from marine or fluvial currents. In its utilization, water turbine plays an important role for taking energy from water current. One of the water turbine types is Cross Flow Water Turbine (CFWT). The performance of the CFWT depends on its geometry. Unfortunately, its geometry is very difficult to be measured using conventional measurement because it has complex geometry. Hence, a non-conventional measurement system based on image processing is proposed in this study to deal with the measurement difficulty of the CFWT geometry.

Abstract: It is a phenomenon that an experience mechanical/ design engineer with years of experience in mechanical parts design, still must to improve the knowledge about process design. This phenomenon will be different with other fields but common in process design because design is continuous process. The automotive industry is expected to be one of the driving factors for economic growth in Indonesia in 2025. It is shown by research firm (Frost & Sullivan) that estimates this year's car sales in Indonesia will rise moderately by 6.5% from a year earlier to 948,500 units and the real car sales in Indonesia rose to 43% in April 2012. Development should be increased because the government provides to industrial facilities that conduct research, development and innovation. Therefore the design process until production is expected to be rapid and immediate product can be enjoyed by society. To speed up the production process, the design process should be faster, and account how the next process that is the production. This research useds the form of the usual features carried with three machining processes are widely used in the world of mechanical component industries. The processes are turning (around 24.9% of machining process), milling (around 20.2% of machining process) and drilling (around 28.2% of machining process). The overall mean of the three processes around 73.3% of the portion of the machining process (survey conducted by PERA).

Abstract: This paper presents the application of Taguchis method of orthogonal array and signal to noise ratio with logical fuzzy reasoning for multiple output optimization of turning AISI H13 steel using carbide tool. The cutting parameters, i.e., cutting speed, feed rate, depth of cut and nose radius, are optimized with considerations of multiple performance characteristics such as cutting force, feed force, surface roughness and tool flank wear. Experimental results are provided to illustrate the effectiveness of this approach.

Abstract: Multipoint forming (MPF) in flexible forming technology. from the previous research of multipoint forming, the configuration of the upper and lower punch matrices were configured in square packing. In this paper, model of multipoint forming configuration was developed and the numerical simulation was performed to investigate the influence of the proposed pins arrangement, hexagonal packing. The packing density in hexagonal arrangement is higher than in square one. The deformation process in multipoint forming with hexagonal packing is evaluated in terms of stress and strains distribution. The results demonstrated that forming tool with hexagonal packing is more efficient than pins arranged in square packing. But dimples and wrinkles as the typical defect of multipoint forming was inevitable consequences of discontinuous contact between the punches and workpiece, appeared. The dimpling phenomenon is more present in MPF with hexagonal packing than with square packing.

Abstract: In the present work, a multi-gender bike, which can be used by men and women, was designed. The integrated design method is used to develop a bicycle frame. As a human transportation the frame is must be light, strong, and comfortable for rider. The frame of bicycle is built with the material of aluminum alloy T-6061 and is produced as prototype for a multi gender purpose. With 100 kg load the strength of material is calculated, and the result shows that the frame critical strength is smaller than material ultimate strength. The prototype was tested by 5 respondents who have an average weight of 68.2 kg, and height 169.4 cm. Pedal test is conducted with 5 level of speed such as 6, 8, 10, 12, and 14 mph in 6 minutes of cycling respectively. The paddle energy during cycling was determined. The results show that the paddle energy increase and follow the increasing of speed. However since 10 mph of speed the paddle energy tends to be fixed with average value of 40 kcal. Therefore the tension leg muscles before and after cycling is going together by increasing the speed. The RULA method is used for determining the ergonomic of multi-gender bicycle, and the result shows that the value of risk injury is 3, that mean the developed bike is ergonomic.