Advanced Materials Research Vol. 576

Abstract: In this paper an OG-7 warhead was modeled using Autodyn SPH solver. The results were compared with the pit test and analyzed by Held’s formula for fragments mass distribution. The results of Autodyn SPH showed good agreement considering of the effects of the mass losses and fragments impact during the pit test.

Abstract: Buckling and crushing behaviour of hollow structure was studied through experiments and numerical simulation. The experimental material was a thin aluminium square tube (38 x 38, 1.2 mm thick). Quasi-static crushing load was applied using a Universal Testing Machine, Shimadzu Autograph (AG-X) series which uses TRAPEZIUMX software for control and data logging. Finite element simulation of the crushing test was done using LS-DYNA software. Results of the two analyses were compared and found in good agreement. The study provides an insight on ways to increasing energy absorption of light weight aluminium tubes. The simulation procedure can be used for further investigation of aluminium tubes of different cross section areas and geometries.

Abstract: This study investigated the initiation and propagation of cracks until fracture of aluminum alloy 7075 under cyclic loadings. Tests were conducted to generate fatigue failures from 1×103 to 4×104 cycles at 10 Hz. Nondestructive ultrasound technique was used to detect the presence of any crack as well as its growth. Finite element analysis was conducted in order to assess the ability to predict fatigue crack initiation behavior. The results obtained from the fatigue test were compared to those obtained using ANSYS and a good agreement between the two was observed.

Abstract: Chatter is an unwanted phenomenon in metal cutting that involves violent vibrations of the cutting tool resulting in marked reduction in tool-life and increased roughness of the cut surface. Researchers have shown that chatter occurs due to resonance of the machine-tool-work system‘s natural frequency with that of the secondary saw teeth chip formation. This work investigates the modeling and free vibration analysis of a SANDVIK steel turning tool holder (DSSNR2525M12) set at 50, 70, 100, and 120 mm overhang, with a SANDVIK COROMANT titanium nitride coated carbide insert. The simulated free vibration data is compared to those obtained via experiments. The results show a correlation between simulated and experimentally obtained data for the tool holder set at the 50 and 70 mm. However there is a large discrepancy in results for the 100 and 120 mm overhang cases. This latter difference is unavoidable, due to the experimental test setup whereby the tool holder is clamped within the fixture with only 2 pins as opposed to the more rigid boundary condition applied to the finite element model, whereby the whole holder length within the carriage is rigidly supported at the element nodes. Hence the discrepancy is accentuated as the overhang is increased. This study is part of an ongoing research that aims at modeling and simulating the turning process itself, with the ultimate goal of providing off-line simulation and prediction of chatter.

Abstract: The paper discusses the response and the accuracy of a quarter car model with a non-linear damping force. The non-linear shock absorber model was a result of an experiment that was conducted earlier and the mathematical model was verified. Based on this model simulation responses of the sprung and unsprung masses between a linear and the non-linear damper were compared. The wheel of the quarter car model was excited by a road profile and according to the results the non-linear quarter model showed responses which were not depicted and captured by the linear model.

Abstract: The present paper describes a method for predicting the imminence (hereafter referred as ‘quality’) of the chemical composition of a recycled alloy to that of a standard alloy of aluminum recycled alloy made from aluminum scrap (used automotive components). The present method allows the chemical composition of a recycled alloy to be predicted. The method has been validated experimentally, and the results obtained showed that the composition of the recycled alloy was close to that of the predicted one. These findings indicate that the present method can be successfully used for any other recycled alloys to predict the alloy composition based on the in-coming scrap alloys. In this work, the chemical composition of a synthesized recycled alloy was compared to an ASTM standard alloy with the nearest composition. It was found that the two compositions were very comparable. A deviation factor has been defined in order to understand the quality of the recycled alloy obtained with reference to the ASTM alloy.

Abstract: Traditional wet machining methods using oil based cutting fluids and water based cutting fluids are currently being used widely in the industry. Since oil based cutting fluids contributes to environmental problems, water based cutting fluids were introduced to minimize these effects even though not extensively used everywhere in all parts of the world. Eco-friendly machining is introduced for making the environment a better and healthier place by reducing the amount of contaminants and pollution into the water system. Two biodegradable cutting fluids have been chosen in this study; vegetable oil (palm oil) and water based cutting fluids. The wear behavior of TiCN coated tools is studied for three different cutting speeds (333, 415 and 517 m/min) and at two different cutting parameters; depth-of-cut, d and feed rate, f (d = 0.2 mm, f = 0.4 mm/rev and d = 0.4 mm, f = 0.6 mm/rev). Wear rate for machining using palm oil cutting fluid is lower (longer tool life) than the wear rate obtained from using water based coolants. Palm oil has better lubrication properties compared to water based coolants which have better cooling effects. The optimum cutting parameters for machining T6061 Aluminium alloy using TiCN coated tool is found; 333 m/min (water based) and 415 m/min (palm oil) at a depth of cut of 0.4 mm and feed rate of 0.6 mm/rev.

Abstract: Single cylinder engine is capable of reducing harmful emission to the environment due to reduction in fuel consumption. On the other side, supercharger is known to be able to boost air to substantially improve the fuel economy of passenger cars. However, some amount of power is required by supercharger, thus reducing the efficiency of the engine. For improving the engine efficiency, waste heat energy from coolant is transferred to the boosted air before it flows into the combustion chamber. The system which functions as heat transfer is known as Waste Energy Harvesting System (WEHS). This system has been developed in order to supply enough boosted air for creating massive turbulence effect and auto oxidation to burn 100% of fuel with very short time. WEHS will contribute to reduce power loss due to heat release from the engine as well as reduce power consumed by the supercharger.

Abstract: In ‘Bandung State Polytechnic for Manufacturing’ (POLMAN) Bandung as a vocational education institution, Production Base Education (PBE) is already implemented for years. Through this concept students are doing practical jobs that inquired by real customer from industries, with the Quality-Cost-Delivery (QCD) necessity as well. The student practical program schedule is made structurally, combined with theory and other needed contents according the planned competency for each study program in 3 years (6 semesters). Therefore, so far 2 weeks for practical and 1 week theory alternately is arranged and ran well. Students will then learn all about process and transformation of raw material to product included assembly, but they seem not enough experienced in Operation Management and integrating the related manufacture activities. There are feedbacks that POLMAN graduates have adequate capability in technical matters like designing, machining, fabrication etc. but few skills in managing could still be improved. In 321 program idea, students will get the first 3 semesters for basic matters needed, the next 2 semesters in integrated continually project program and the last 1 semester for finalization and the additional enrichment items. With this program, students will more concern and get better understanding in project handling comprehensively, integrating all related planning, relevancies among one process to others in order handling and manufacture activities, and be realized in controlling the milestone of supply chain component entities like vendor, logistic, production, sales and customer. The consequences in market and project matter preparation of course has to be highly anticipated.

Abstract: In this paper, manufacturing process of aircraft radome via closed mold with vacuum infusion process is presented. Closed mold is needed to get smooth inner and outer surface. The radome mold was formed from the original part of the aircraft Duke 60 Beachcraft. The closed mold is made from fiber glass/polyester composite via hand lay-up technique. Tooling grade vinyl ester gel coat is applied on the mold to produce fine smooth surface and protection. Later, the radome part is fabricated with vacuum infusion and the consistency of thickness is achieved.