Metallurgy Commons^™

Lateral Load Resistance Of Laminated Veneer Lumber Sengonwooden Joints With Wooden Dowels, Niken Palaeowati, Ali Awaludin, Suprapto Siswosukarto

Makara Journal of Technology

Analytical models for wooden-doweled joints need to be developed. The objective of this research is to determine whether the strength of wooden-doweled joints can be well predicted by equations developed for steel-doweled joints. In this experiment, various connection parameters, such as dowel diameter, species of the wooden dowel, and angle of joints, are studied. The joint specimens are loaded in a quasi-static state with four replications each. A5% offset diameter method is used to determine the lateral load resistance of the tested joints, while the predictions are evaluated by equations given in Indonesian National Standard (SNI) 7973-2013 and the European …

Adjustable Resonance Frequency Of Rf-Mems Capacitor By Using Comb- Drive Actuators: A Design Approaches, Agus Santoso Tamsir, Sandy Tannu Wijaya, Dato’ Burhanuddin Yeop Majlis

Makara Journal of Technology

The needs of smaller size RF varactor is a must today, and MEMS comes to be the potential one. In this paper we proposed an adjustable resonance RF-MEMS varactor by using comb-drive actuators placing in each side of the square movable plate. In our preliminary simulation, we found that the device can work properly but some constraints comes such as the dominancies of harmonic resonance frequencies that influences into the nominal capacitances. Therefore for the next step of development we have to find out the window of the structural dimension for a certain spans and a certain operating frequencies.

Make Or Buy Analysis Model Based On Tolerance Design To Minimize Manufacturing Cost And Quality Loss, Cucuk Nur Rosyidi, Reza Rizkichani Akbar, Wakhid Ahmad Jauhari

Makara Journal of Technology

In a manufacturing company, manufacturing costs, or component prices, and tolerance will affect the price and the quality of a product. Companies must produce high-quality products with low manufacturing costs in order to keep their products competitive in the market; however, it is difficult to produce a high-quality product with a low manufacturing cost. Companies have difficulties in determining the components to be produced using their own manufacturing facilities (make) or outsourced to their suppliers (buy). Hence, a make or buy analysis is needed to minimize the manufacturing costs and quality loss and to determine the optimum alternative regarding make …

Observation Of Tunneling Effects In Lateral Nanowire Pn Junctions, Sri Purwiyanti, Arief Udhiarto, Daniel Moraru, Takeshi Mizuno, Djoko Hartanto, Michiharu Tabe

Makara Journal of Technology

As electronic device dimensions are continuously reduced, applied bias conditions significantly change and the transport mechanisms must be reconsidered. Tunneling devices are promising for scaled-down electronics because of expected high-speed operation and relatively low bias. In this work, we investigated the tunneling features in silicon-oninsulator lateral nanowire pn junction and pin junction devices. By controlling the substrate voltage, tunneling features can be observed in the electrical characteristics. We found that the minimum substrate voltage required for tunneling to occur in pn junctions is higher as compared with pin junctions. The main cause of these effects relies in the difference between …

Argon Ion Irradiation Effect On The Magnetic Properties Of Fe-Al2o3 Nano Granular Film, Setyo Purwanto, Isao Sakamoto

Makara Journal of Technology

We studied the effect of Argon (Ar) ion irradiation on Fe-Al2O3 nanogranular thin film. X-ray diffraction (XRD) patterns show that the ion dose might promote the growth of the Fe2O3 phase from an amorphous phase to a crystalline phase. The magnetic and magnetoresistance properties were investigated using a vibrating sample magnetometer (VSM) and a four point probe (FPP). The results suggest that percolation concentration occurred at the 0.55 Fe volume fraction and with a maximum magnetoresistance (MR) ratio of 3%. The present MR ratio was lower than that of previous results, which might be related to the existence of the …

Digestibility Of Betung Bamboo Fiber Following Fungal Pretreatment, Widya Fatriasari, Wasrin Syafii, Nyoman J. Wistara, Khaswar Syamsu, Bambang Prasetya

Makara Journal of Technology

This research evaluated the effect of fungal pretreatment of betung bamboo fibers and enzymatic- and microwaveassisted hydrolysis on the reducing sugar yield. The enzymatic hydrolysis of the pretreated biomass was carried out with cellulase and 10 and 20 FPU/g of substrate in a shaking incubator at 50 °C and 150 rpm for 48 h. The sulfuric acid concentration used in the microwave-assisted acid hydrolysis was 1.0, 2.5, and 5%, either with or without the addition of activated carbon. Microwave irradiation (330 Watt) was applied for 5–12.5 min. The yield of reducing sugar was better with the microwave-assisted acid hydrolysis, and …

Electron Emission Characteristics Of Multi-Gated Field Emitters, Hidenori Mimura, Yoichiro Neo, Toru Aoki, Tomoya Yoshida, Masayoshi Nagao

Makara Journal of Technology

We have developed a multi-gated field emitter (FE) such as a quadruple-gated FE with a three-stacked electrode lens and a quintuple-gated FE with a four-stacked electrode lens. Both the FEs can focus the electron beam. However, the quintuple-gated FE has a stronger electron convergence than the quadruple-gated FE, and a beam crossover is clearly observed for the quintuple-gated FE.

Properties Of Lignin From Oil Palm Empty Fruit Bunch And Its Application For Plywood Adhesive, Lucky Risanto, Euis Hermiati, Yanni Sudiyani

Makara Journal of Technology

Lignin from lignocellulosic biomass is a potential biopolymer for wood adhesive. The aims of this study were to characterize lignin isolated from the black liquor of oil palm empty fruit bunch fiber pretreated with steam explosion in alkaline conditions and to examine the bond quality of aqueous polymer isocyanate (API) adhesive prepared from lignin, natural rubber latex (NRL), and polyvinyl alcohol (PVA) as base polymers with isocyanate crosslinkers. Lignin was precipitated from the black liquor by adding hydrochloric acid; then the precipitate was separated by filtration, thoroughly washed with water up to pH 2 and pH 5, and dried. The …

The Gaussian Orthogonal Laplacianfaces Modelling In Feature Space For Facial Image Recognition, Arif Muntasa

Makara Journal of Technology

Dimensionality reduction based on appearance has been interesting issue on the face image research fields. Eigenface and Fisherface are linear techniques based on full spectral features, for both Eigenface and Fisherface produce global manifold structure. Inability of them in yielding local manifold structure have been solved by Laplacianfaces and further improved by Orthogonal Laplacianfaces, so it can yield orthogonal feature vectors. However, they have also a weakness, when training set samples have non-linear distribution. To overcome this weakness, feature extraction through data mapping from input to feature space using Gaussian kernel function is proposed. To avoid singularity, the Eigenface decomposition …

Series-Interconnected Plastic Dye-Sensitized Solar Cells Prepared By Low- Temperature Binder-Free Titania Paste, Erlyta Septa Rosa, Lia Muliani, Shobih Shobih, Jojo Hidayat, Brian Yuliarto

Makara Journal of Technology

The aim of this research is to study dye-sensitized solar cells (DSSC). This was implemented on a flexible polyethylene terephthalate (PET) substrate using a mixture of transparent and scattered mesoporous anatase-titania as the electron transport layer for the photoelectrode. This mixture of anatase titania performed a dual function of light scattering and efficient dye absorption. In this study, a porous nano-TiO2 film was prepared on indium tin oxide (ITO) coated polyethylene terephthalate (PET) by using a binder-free titania paste; on it, a DSSC was fabricated. The paste which contained a mixture of TiO2 nanoparticles, acid chloride, and ethanol was printed …

Atomistic Simulation And Virtual Diffraction Characterization Of Alumina Interfaces: Evaluating Structure And Stability For Predictive Physical Vapor Deposition Models, Shawn Patrick Coleman

Graduate Theses and Dissertations

The objectives of this work are to investigate the structure and energetic stability of different alumina (Al₂O₃) phases using atomistic simulation and virtual diffraction characterization. To meet these objectives, this research performs molecular statics and molecular dynamics simulations employing the reactive force-field (ReaxFF) potential to model bulk, interface, and surface structures in the θ-, γ-, κ-, and α-Al₂O₃ system. Simulations throughout this study are characterized using a new virtual diffraction algorithm, developed and implemented for this work, that creates both selected area electron diffraction (SAED) and x-ray diffraction (XRD) line profiles without assuming …

Wetting And Reactivity Of Active Metal Braze Alloys On Tungsten Carbide, Hayden Peck, Alan Meier, Ph.D.

2014 Undergraduate Research

Background

Tungsten carbide is useful because of its hardness and strength. Joining of dissimilar materials especially non-metallic materials is very challenging. Active metals such as titanium can be added to a ductile filler metals such as copper to get wetting via a reduction reaction.

Conclusions

All alloy conditions wet the tungsten carbide/cobalt substrates. Two different interfacial reaction types were observed: dissolution and reduction reactions. An important issue has been identified: the braze interface reactions change the chemistry of the braze alloy which change the interaction between the braze alloy and the other material substrate.

Influence Of Grain Size And Widmanstätten Colonies On Variability Of Tensile Properties Of Forged Ti-6al-4v, Blake T. Gaspar

Master's Theses

When testing forgings for specifications, it was found that some parts did not meet the requirements for mechanical properties. This triggered an investigation into two of the parts from the lot that did not meet specification. The ultimate reason for failure was due to lower than necessary yield strength and ultimate tensile strength values, as well as unwanted variability between regions of the part. Therefore, samples of the regions were tensile tested to determine the differences that existed in yield strength, ultimate tensile strength, and elongation. After tensile testing, quantitative metallography and fractography were conducted to identify aspects of the …

Electrochemical Characterization Of Precious Metal Braze Alloys Using Potentiodynamic Polarization, Maxwell Glen Martin, Mason Gregory Morgan, Matthew David Vance

Materials Engineering

This study aimed to characterize the electrochemical behavior of six precious metal braze alloys by performing potentiodynamic polarization tests (ParStat 2273) based on ASTM Specifications G5 and G59. To determine the extent to which the alloys will contribute to galvanic corrosion in a marine environment (3.5 wt% NaCl), corrosion analysis software was used to produce fitted Tafel lines to determine the open circuit potential, V_oc, for each alloy. The V_oc values for the alloys were found to be -66.58 mV for Gold ABA, 13.01 mV for Nicoro^®, -39.00 mV for Nioro^®, 23.4 mV …

A Process Development Study On Reducing The Anisotropy While Maintaining The Strength Of Extruded Aluminum Alloy 2195 Through Heat Treatment, Theodore James Arehart

Materials Engineering

The purpose of this study was two-fold: develop an aging curve for extruded 2195 aluminum and test the magnitude of the anisotropy in the extrusion throughout the aging process. Two aging curves were developed, one at 290^oF and the other at 320^oF, through hardness tests of aged samples. The hardness was found to change, from approximately 72 HRB to 90 HRB, within the first 6 hours and not change more than 2 HRB in the 42 hours following. It was determined that the 320^oF temperature was more promising due to faster aging time, and …

High Cycle Rotating Bending Fatigue Of 6061-T6 Friction Stir Welded Extrusions, John Chang, Travis Miller

Materials Engineering

Fatigue testing was done on friction stir welded joints of 6061-T6 aluminum extrusions. Tests were run using a rotating bending fatigue machine at stresses from 111.5 to 138.7 MPa. Failures occurred on the order of 10⁵ to 10⁷ cycles, and an S-N curve was generated based off of the failure results. After the samples failed, the location of the failure and the number of cycles to failure were noted. Fatigue samples were designed in SolidWorks with a tapered 2 inch reduced section. The 2 inch reduced section will include the entire weld region as seen from the microhardness …

Relationship Between Bagging Methods And Pre-Weld Holding Times On Porosity Formation In 2219 Aluminum Ac-Tig Welds, Mariah Grace Head, Tyson Daniel Mobley

Materials Engineering

The purpose of this study was to determine relationships between bagging methods and pre-weld holding times on the formation of porosity when AC-TIG welding 2219 aluminum. Considering the strict guidelines and specifications required within the aerospace industry, maintaining quality welds is of paramount importance to control part integrity for aerospace applications. This project focused on two parameters involved in the preparation of aluminum parts for welding: bagging method and pre-weld holding time. Welding geometry was simplified to bead-on plate instead of the standard joint welds. Radiographic analysis of the samples showed that all levels of both parameters produced “passing welds.” …

An Intercritical Heat Treatment Study Of High Strength, Microalloyed Ferrous Open Die Forgings, Kelly Elizabeth Stewart

Materials Engineering

High strength, low alloy steel is most commonly utilized in plate or sheet form-with a thickness under 4 in, one unconventional application however, is open die forging where cross-sectional area can be as large as 9.5 in by 11.5 in. When forging to larger section size than one would thermo-mechanically roll sheet steel, a new set of complications, such as variation in microstructure and mechanical properties, arise. This study investigates the heat treatment and processing options needed to negate the inherent microstructural irregularity and Charpy V-Notch (CVN) toughness variation. Intercritical heat treatment—normalizing and then quench and tempering above the A …

The Effect Of Silicon On The Electrochemical Corrosion Resistance Of Carbon Steel, Loan Faget, Michael S. Rouse

Materials Engineering

The purpose of this study was to investigate how the silicon (Si) content of carbon steels affects their electrochemical corrosion resistance. Tests were conducted using concentrated HCl and carbonated water on three carbon steels with different levels of silicon: 0.02, 0,19, and 0.94 weight percent. Like H2S, the prime concern of Chevron, HCl and CO2 are corrosive components in oil refinery. Electrochemical properties were measured using a potentiodynamic test outlined in Standard ASTM G59-97: Test Method for Conducting Potentiodynamic Polarization Resistance Measurements. Previous studies have determined that adding silicon to steel increases the corrosion resistance; however, results show that corrosion …

The Effects Of Austempering And Cryogenic Processing On The Mechanical Properties Of Forged E4340 Steel For Automotive Engine Connecting Rods, Aaron Taylor Ludlow

Materials Engineering

The components in top-fuel dragster and stock car engines undergo significantly more force than their production passenger vehicle counterparts do. Therefore, they must be manufactured and processed to withstand those forces so that they do not catastrophically fail while in service. In this project, the effects of austempering and adding a cryogenic processing step to the control quench and double temper heat treatment on the tensile and hardness properties of E4340 high-strength steel were examined. Tensile test samples were machined from raw connecting rod forgings and underwent either a quench-double temper heat treatment, an austempering heat treatment, or the quench-double …