Yudy Surya Irawan

Morphology, Structure, and Mechanical Properties of Natural Cellulose Fiber from Mendong Grass (Fimbristylis globulosa)

This study was to investigate the morphology, structure, and chemical properties of the Mendong fibers extracted from Mendong grass (Fimbristylis globulosa) in the form of raw and treated fiber by alkali-included chemical content and functional group and to evaluate the strength and properties of Mendong fibers compared with other natural fibers. These studies explore the chemical properties of the fiber including fiber composition and functional group by FTIR, mechanical properties of fiber, and the structural and morphological analysis of the fiber using SEM and XRD. The results showed that the chemical contents of Mendong fibers were 72.14% cellulose, 20.2% hemicellulose, 3.44% lignin, 4.2% extractive, and moisture of 4.2%–5.2%. Mechanical properties of the fiber were a strong character with tensile strength of 452 MPa, and modulus of 17 GPa. The structural properties of Mendong fiber such as crystallinity, crystalline index, microfibril angle, and crystalline size were 70.17% and 58.6%, 22.9°, and 14.3 nm, respectively. This fiber has competitive advantages compared with other natural fibers and can be developed further as a potential reinforcement of polymer matrix composites.

Effect of Alkali Treatment on Crystalline Structure of Cellulose Fiber from Mendong (Fimbristylis globulosa) Straw

The research aim is to investigate the effect of alkali treatment on the crystalline structure of Mendong fiber. The experiment was conducted by immerse fibers in 100 ml NaOH solution by a concentration of 2.5%, 5%, 7.5%, and 10% for 2 hours at the room temperature. The specimens were characterized by X-ray diffraction method. The morphology of fiber treated by alkali was observed by Scanning Electron Microscope. The result shows that the crystalline structure of cellulose in Mendong fiber was changed in alkali treatment. It was found that both the degree of crystallinity and crystalline index of Mendong fiber was increased until alkali treatment concentration of 7.5%.

Improvement of Interfacial Shear Strength of Mendong Fiber (Fimbristylis globulosa) Reinforced Epoxy Composite Using the AC Electric Fields

The effects of the AC electric field treatment on the interfacial shear strength of mendong fiber-reinforced epoxy composites were investigated. For this purpose, the epoxy (DGEBA) with a cycloaliphatic amine curing agent was treated by the AC electric field during the curing process. The heat generated during the epoxy polymerization process was monitored. Structure of the epoxy was studied by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and Scanning Electron Microscope, respectively. The interfacial shear strength (IFSS) was also measured using a single fiber pull-out test. XRD analyzes indicated that the treatment of AC electric fields was able to form a crystalline phase of epoxy. IFSS of the mendong fiber-reinforced epoxy composites was optimum increased by 38% in the AC electric fields treatment of 750 V/cm.

Tensile Strength of Weld Joint Produced by Spinning Friction Welding of Round Aluminum A6061 with Various Chamfer Angles

Tensile strength of Aluminum A6061 joint produced by spinning friction welding (SFW) with various chamfer angles was studied. Tensile strength test specimens that have weld joint part at their centers were machined from spinning friction welded base metals. SFW specimens were prepared by making various chamfer angles of 15, 30, 45, 60, 75 degree and without chamfer angle on both contact-surfaces of base materials. It was found that chamfer angle affected tensile strength of weld joint of Aluminum A6061. Base materials with chamfer angle of 30 degree resulted in specimen that had the maximum tensile strength of friction weld joint. From the result of macrostructure evaluation, it was found that high strength in these specimens was due to the maximum area of fully plasticized zone, minimum porosity and minimum area of heat-affected zone.

Characterization of the Chemical, Physical, and Mechanical Properties of NaOH-treated Natural Cellulosic Fibers from Corn Husks

ABSTRACT This paper focuses on the chemical, physical, and mechanical properties of corn husk fibers treated with different concentrations of NaOH (0.5%, 1%, 2%, 5%, and 8%) for 2 h. The results show that treatment with NaOH removed the hemicellulose and lignin in the fibers and decreased the moisture content. Consequently, the chemical, physical, and mechanical properties of the treated fibers were greatly improved. Scanning electron microscopy analysis indicated the presence of rough surfaces and a number of lumens inside the fiber bundles. The results suggest that the treated corn husk fibers exhibited better mechanical properties than fiberglass.

Torsion strength of continuous drive friction weld joint of round bar aluminum A6061 affected by single cone geometry of friction area

This paper describes the effect of single cone geometry of friction area on torsion strength of continuous drive friction weld (CDFW) joint of round bar aluminum alloys A6061. Single cone geometry on friction area was determined with ratio of upper diameter (D1) and lower diameter (D2), D1/D2 of cone. Ratios of D1/D2 used were 0.02, 0.25, 0.65, 0.8 and 1. Friction time was 120 seconds. Torsion strength test, macro and microstructure, micro-hardness test were conducted. The results show that D1/D2 of 0.25 gives maximum torsion strength of CDFW joint. It is thought that it occurs due to the wider area of Zpl zone, smaller grain size and more Mg2Si precipitate in the Zpl and Zpd zone and nil or minimum porosity in the CDFW joint.

Effect of Low Temperature Sintering on the Porosity and Microstructure of Porous Zeolite Ceramic

Manufacturing a porous ceramic specimen from natural zeolite materials mined in Malang, Indonesia was conducted by using a low temperature sintering. In this study, a porous ceramic property with rectangular shaped and prism shaped fillets at each end were sintered at 800-900°C and finally were investigated. Density and porosity measurements were performed using Archimedes method. The microstructure photos were used to measure the neck diameter and the contact angle between the two grains particles and two-dimensional porosity. The result of the zeolite ceramic measurement shows that the higher the sintering temperature the higher the density value and the smaller the open porosity. While from the microstructure photo it is shown that the neck diameter was larger the contact angle was wider. This phenomenon was happened because of the flux diffusion on the grain boundaries. This diffusion flow condition would influence the specimen surface, volume and grain boundary so that the porous ceramic density increases.

System Architecture and FPGA Embedding of Compact Fuzzy Logic Controller for Arm Robot Joints

This research is about the system architecture for embedding of the Compact Fuzzy Logic Controller (Compact-FLC) into the FPGA with a minimal need in device resource. This exciting research is to minimize the FPGA resources needed to build Compact-FLC based on FPGA for controlling each joint of arm robots manipulator. Compact-FLC results of this research have been used in the XILINX Spartan 3 XC3S1000 FPGA.The Compact-FLC has been applied with satisfactory results as Servo Controller for one joint of arm robot manipulator which the results showed that the controller achieved a process speed of 65,4uS, which is equivalent to a maximum sampling frequency of 15.290 KHz. Output membership function in this Compact-FLC used singleton membership function with Center Of Area algorithm. Two input membership functions, i.e E (Error) and CE (Change Error) have been used, both formed from several combination of triangular membership functions. The maximum number of fuzzysets that can be processed is sixteen. The overlapping function is not limited because there have been 256 if-then rule available as look up table in FPGAs ROM.The device utilization summary from ISE of XILINX development software gave the following data: Slice FlipFlops needed are 3869 or 25% of 15360 availability, 4 input LUT needed are 2319 or 15% of 15360 availability, Blocks of RAM needed are 4 or 16% of 24 availability, MULT18x18s needed are 2 or 8% of 24 availability, GCLKs needed are 2 or 25% of 8 availability, Bonded IOBs needed are 32 or 18% of 173 availability.

Bearing Damage Detection Based on Sound Signal

This paper presents a new method in damage detection by taking the sound signals of the rolling bearings in different levels. The tested bearing was put on the end of the shaft rotated by permanent magnet synchronous motor. The sound signal produced by this rig was recorded separately for each bearing condition with the same experimental environment. The sound data signals are compared each other. Based on the cross-correlation analysis, the recorded sound signal proved that the signals were recorded with the same environment. The power spectra calculation has shown different harmonic frequencies according to various bearing conditions. The total power of the sound is decreased along with the increasing damage. This is also confirmed by the auto-correlation of each sound signal that shows the appearance of the sounds impulse repetition with a wider period.

Architectural System Design of Six Channels Compact Fuzzy Logic Controller for Arm Robot Joints Using FPGA Technology

The purpose of this study is to develop the architectural system design of the Six Channels Compact Fuzzy Logic Controller (SCC-FLC) ready to be embedded into the FPGA (Field Programmable Gate Array) for joints of arm robots manipulator. The FPGA based system design of this study could controlled independently six servo of arm robot manipulators to reduce workload of computer system. The method of this study divided into four steps. The first step, the FLC-P (Fuzzy Logic Controller Processor) block module of single channel C-FLC (Compact Fuzzy Logic Controller) on the previous study is redesigned in architectural system design by adding lots of block modules using multiplexing method. The second step, the module interconnections of system architecture are designed by defining some of inputs and output ports. The third step, the specific function of block modules about working processes is determined based on the definition of input and output ports. The fourth step, sequences of multiplexing processes are determined based on the algorithm of FLC, thus the total processing time of SCC-FLC could be estimated from architectural system design. Architectural system design of SCC-FLC requires external chips are 12bit ADC MAX-186 chip and 12bit DAC MAX-3203 of six chips. The block modules of SCC-FLC are FLC-P, LUT-MBFs (Look Up Table of Membership Function), ADC-I (Analog to Digital Converter Interface), DAC-I (Digital Analog Converter Interface), ECEG (Error and Change Error Generators), SPL (Set Point Latchs) and TAC (Time And Control). The total processing time of SCC-FLC by estimation is 256.2 µS or sampling frequency of 3.907KHz using clock frequency of 100MHz.