Applied Mechanics and Materials Vol. 372

Abstract: Machining of sculptured surfaces engender abrupt variations in cutting forces, excessive tool deflections and undesirable vibrations and therefore poor surface finish. To reduce these problems and to have a stable machining it is more indispensable to select the appropriate cutting conditions. The aim of this paper is to propose an approach for determining the optimum feedrates along tool path during finishing of sculptured surfaces with ball end tools on 03-axis CNC milling machines using a predictive mechanistic model of cutting forces. Its steps are :1) approximation of the workpiece geometric model by dexels, 2) localization of the contact zones between tools and workpiece using machining simulation, 3) prediction of the cutting forces, 4) optimization of the feedrates and 5) updating of the machining program « G-Code ».

Abstract: The thermal water-jet technology and mechanical milling method are comprehensively applied in the design of the new de-icing device. These two kinds of de-icing methods are combined as a set of multi-functional system, in which the thermal water jet cuts the ice layer into separated sections, and then the mechanical milling unit can easily remove the remaining sections. To obtain the affecting factors in the new de-icing device, repeated indoor experiments were conducted and the data was analyzed, which would provide some theoretical references to further optimize the design.

Abstract: The flow structure inside a water basin that, serves as a water tank of a modeled washer system with an immersed coiled heater and air supply nozzle is investigated experimentally. To obtain the flow velocity field, particle image velocimetry is employed, and different view-point sections are analyzed. A large-scale vertical flow structure, which is attributed to the strong air jet flow enhancement, causes the development of a 3D mixing layer in the entire flow regime. Although a coiled heater can provide buoyancy to the working fluid, the bubbly flow structure significantly dominates this stage by supplying air from the bottom nozzles.

Abstract: In order to reveal the Intermixture of Different Modals of Ultrasonic motor, a complete analysis about the modal types and excitation responses were analyzed by finite element analysis. The intermixture of different modals of the stator and its performance under shock excitation are found while doing modal analysis. Through the sensitivity analysis of modal frequency to structural parameters, the separation technique of stator modes is found, which can solve the intermixture problem and provide basis for accessing the structural design

Abstract: This study proposes the research method to examine through experiment the mechanical properties of final products based on the size and sintering temperature of powder particle during STS630 powder based metal injection molding and heat treatment processing condition after the sintering. The feedstock for the injection was manufactured based on STS630 powder with the diameter of 7.0±1.0μm and 8.0±1.0μm and the sintering was carried at 2 temperature conditions of 1300°C and 1355°C after the injection and debinding process. Heat treatment conditions of sample after the sintering were divided into 2 types thus final samples of total 8 cases were manufactured. Then, the 5 types of mechanical properties test were conducted. Optimal processing conditions for MIM molding and heat treatment of STS630 powder could be established based on it.

Abstract: The current trend in abrasive water jet machining process is getting focused on milling applications using this technique. Abrasive water jet machining (AWJM) process is a well defined process for cutting or part separation. The present paper reports on the geometry obtained in controlled depth milling process of different materials. The dimensions considered in this paper are the pocket depth and the change in the kerf profile. Experimental observations are made relating the kerf profile with traverse speed and the mechanical properties of the work piece material. Tool paths for obtaining the pocket of size 9 mm x 20 mm are generated in raster mode and machined using AWJM on materials of varying hardness and at different traverse speeds. It is observed that there is a significant change in the geometry of the kerf profile and also the depth of the pocket with speed in conjuction with the material hardness.

Abstract: Experimental studies of ventilation air methane oxidation were carried out in a thermal flow-reversal reactor and a fixed bed reactor in laboratory scale respectively. The reaction characteristics of ventilation air methane in a fixed bed reactor were investigated. The influence of the feed gas velocity and the lean methane concentration on the temperature profile in the thermal flow-reversal reactor was studied. The internal temperature uniformity of the cross section and the cavity of the flow-reversal reactor which have influence on lean methane conversion have also been discussed and analyzed. The results shows that the oxidation of lean methane needs to meet the ignition temperature condition and the residence time condition, and the temperature distribution in the thermal flow-reversal reactor is mainly related to the methane concentration and the feed gas velocity while the methane conversion rate is mainly related to the temperature and the residence time in the high temperature zone of the reactor.

Abstract: Due to the biaxial oriented PVC (PVC-O) pipes have a great improvement in the strength, heat resistance, modulus, and impact resistance, etc. So the new products can be used in many situations. Referring to the foreign Mouth die drawing method, the mechanism of quasi-dynamic expansion method is proposed in the paper. We chose the hard polyvinyl chloride (PVC-U) pipes for raw materials, through the forward movement of the pipe match with the vertical reciprocating movement of the expansion parts, improve the design of a whole package of biaxial oriented self-reinforced pipe continuous production device. The device has great advanced properties: small expansion friction resistance, high hoop extension ratio, simple production device, production line is easy to start etc.

Abstract: Talc and magnesium oxide are used to prepare forsterite (Mg₂SiO₄) powder by solid-state reaction with ball milling method. The samples were sintered at temperature 1200°C, 1300°C, 1400°C and 1500°C with four different holding time duration 2 hours, 1 hour and 1 minute with ramp rate of 10°C/min respectively via conventional pressureless sintering method. 3 hours ball milling is sufficient to form pure forsterite without any secondary phase. Highest values for fracture toughness (3.8 MPa.m^1/2) and Vickers micro-hardness (5.0 GPa) recorded with sintering temperature 1500°C with 1 hour holding time which makes forsterite suitable potential for biomedical application.

Abstract: The object of this project was to study the effect of drying temperature on physical quality and sensory evaluation of germinated brown rice soaking with tumeric and roselle. The drying was run under the conditions of drying temperatures of 80-100°C and air velocity of 7.3 m/s. Initial moisture content of brown rice samples was of 54-55% dry-basis and was dried until the final moisture content reached to 20-25% dry-basis. After drying, the rice was tempered and then was ventilated by ambient air until its moisture content reached to 14-15% dry-basis. The experiment showed that highest drying rate is incident at 100°C. For physical qualities analysis, the results showed that the drying air temperature does not affect to head rice yield, fissured kernels, chalky grain and color (L*, a*, b* CIE-lab unit) of herbal germinated brown rice. In addition, herbal germinated brown rice drying can maintain low percentage of chalky grain compared to commercial brown rice. The soaking solution was not affect to drying rate. Finally, the sensory evaluation showed that the herbal germinated brown rice dried with all drying conditions was acceptable taste (>5).