Applied Mechanics and Materials Vol. 372

Abstract: Basically, permeability of ceramic shell mould system play an important role in minimizing the casting defects in most investment casting shell. The mould has to be sufficiently permeable to obtain complete mould filling during casting process. Mould fill can be improved by increasing the open porosity that definitely will increase permeability ceramic shell mould. The elimination of rice husk volatile elements has contributed to the increment of pore structure that provides a great deal of connected pathways through the ceramic shell which directly will increase the permeability of the ceramic shell mould during casting process. Indeed, the rice husk fibers additions increase the permeability after firing by a factor 3 compared to the standard shell mould system (without fiber) that makes its an excellent alternative in producing higher permeable ceramic shell system.

Abstract: In the fields of materials science and engineering, measuring temperature has become one of the most fundamental and important issues. In particular, there are growing demands for monitoring temperature gradient and its transient variation of materials being processed at higher temperatures because the temperature state during processing crucially influences the quality of final products. Such temperature monitoring is also required for rotating machining processes such as tuning, milling and friction stir welding (FSW). In this work, a new noncontact method for monitoring temperature distribution of a heated rotating cylindrical object is presented. A laser-ultrasonic technique is employed in the method. Surface temperature measurements for the cylindrical object using the laser-ultrasonic technique and heat conduction analyses are combined together for making quantitative evaluation of temperature distribution in the radial direction of the cylindrical object. To demonstrate the feasibility of this method, an experiment with a steel cylinder of 100 mm in diameter rotating at 300 min^-1 and heated up to 100 °C on the surface is carried out. A pulsed laser generator and a laser Doppler vibrometer are used for generating and detecting surface acoustic waves (SAWs) on the steel cylinder, respectively. Measured SAWs are used for determining both surface and internal temperatures of the cylinder. As a result, the estimated temperature distributions during heating almost agree with those measured by an infrared radiation camera.

Abstract: A comprehensive study of the internal flow field for the prilling application in a perforated rotating bucket has been carried out. Computational Fluid Dynamics (CFD) is used to investigate the flow field of urea melt inside the perforated rotating bucket. The bucket is mounted at the top of the prilling tower. In prilling process, urea melt is sprayed by the perforated rotating bucket to produce the urea droplets, which falls down due to gravity. These drops fall down through a cooling medium and solidify into prills. The velocity field in the bucket is very important to study, as it has great effect on the heat and mass transfer performance in prilling process. ANSYS 14.0 CFD package is used to simulate and Design Modeler and Catia V5 are used for geometrical model of the perforated prilling bucket. Velocity distribution on different planes are obtained and discussed.

Abstract: In this study, thermal performances of counter flow Ranque-Hilsch vortex tubes were experimentally investigated and modeled with a Rule Based Mamdani-Type Fuzzy (RBMTF) modeling technique. The vortex tubes were made of brass. Diameter of vortex tube (D) was 10 mm. Length of vortex tube (L) was 10D, 11D, 12D, 13D, 14D. Input parameters (ξ, L/D) and output parameters (ΔT_h, ΔT_c) were described by RBMTF if-then rules. 45 experimental data sets were used in the training step. R² for the ΔT_h was found to be 99.42 % and R² for the ΔT_c was 99.66 %. The actual values and RBMTF results demonstrated that RBMTF can be successfully used for the determination of heating and cooling performances of counter flow RHVT with different geometric constructions for brass.

Abstract: In this study, heating and cooling performances of counter flow Ranque-Hilsch vortex tubes (RHVTs) were experimentally investigated for brass. The vortex tubes were made of brass. Diameter of vortex tube (D) was 10 mm. Length of vortex tube (L) was 15D, 16D, 17D and18D. The number of nozzles (Nn) was 5. The conical edges of the plugs have a slope of 30o angle. Working pressure of Ranque-Hilsch was 460 kPa (absolute). According to the experimental results, the maximum heating performance of the RHVT system was found to be 39,5 °C at P₁₇ and the maximum cooling performance of the RHVT in this study was found to be-28,6 °C at P₁₈. An increase in fraction of cold flow (ξ) led to a increase in the heating performance.

Abstract: the temperature control accuracy of polymer melt is the main factor affecting quality precision of final products. In this paper, we study the method of improving the precision of temperature control based on control system of micro injection molding machine. In order to avoid big overshoot in the traditional PID control, we use gradual approximation control method based on gradual approximation mathematical algorithm to realize fast and accurate temperature control of the micro injection molding machine. Experiment results show that effective combination of the traditional PID and gradual approximation method can realize accurate temperature control of micro injection molding machine, and precision of temperature control can be improved up to±0.5°C.

Abstract: With orthogonal optimization method, the impact of the ratio and addition of flux and melting temperature on the recovery and metal impurity quantity of waste aluminumcan is researched, and the optimal purification process is obtained:Formula 3 flux, melting temperature 740°Cand flux addition 4%. In this condition, the recovery rate is 89.3%, flux addition is 0.1024%. Furthermore, the ratio and addition of flux have a significant effect on the waste aluminum cans purification is concluded.

Abstract: This paper presents the effect of high speed micro end milling parameters on tool vibration during machining of poly (methyl methacrylate) (PMMA). The main focus is to achieve minimum tool vibration by controlling the cutting parameters; spindle speed, feed rate and depth of cut. An empirical model for tool vibration has been developed using Taguchi method. The orthogonal array, signal-to-noise ratio and analysis of variance revealed that high spindle speed is the most influential parameter to increase the level of tool vibration.

Abstract: Tooling plays important role in ensuring precision of cold forging part. In this study, a modular approach was proposed in the design of the tooling in the production of Autonomous Underwater Vehicle (AUV) propeller blade. Based on the conceptual design and optimization of the process sequence, the tooling was designed. As a result, the precision of the forged blade is still within the acceptable level.

Abstract: This work is concerned with control and inverse problems for the Oberbeck-Boussinesq model of heat convection. Optimality system describing the first-order necessary optimality conditions is deduced. Numerical algorithm based on Newton's method is proposed.