Advanced Materials Research Vols. 264-265

Abstract: It is known that polystyrene must be chemically modified to make its surface amenable to covalent cross-linking with protein. The aim of this study was to set up a UV/Ozone system and investigate the effects of UV/Ozone treatment on polystyrene surface. Microsize polystyrene beads with an average size of 150 μm in diameter were treated with and without distilled water at the same treatment time, ozone flow-rate and UV intensity. The treated beads were analyzed by ATR-FTIR, SEM, EDX and hydrophilicity measurement. The results show that the hydrophilicity of the surface of polystyrene beads was increased after the UV/ozone treatment and the introduction of carbonyl, carboxyl and hydroxyl groups on the polystyrene beads surface was also confirmed. It was demonstrated that the UV/Ozone system was effective for treatment of polystyrene bead and the best result was obtained without distilled water.

Abstract: The sinterability of hydroxyapatite (HA) powder synthesized through a novel wet chemical method (HAp) and a wet mechanochemical method (HAwm) was investigated over a temperature range of 1000oC to 1400oC in terms of phase stability, bulk density, hardness and fracture toughness. The results indicated that the sinterability of HAp powder were significantly better than HAwm powder. Moreover, the XRD traces of HAwm sintered samples showed signs of decomposition into TTCP when sintered at 1300oC and above. Densification of ~98% of theoretical density was attained by HAp compacts at 1100oC while the HAwm compacts exhibited only ~96% of theoretical density even at 1350oC with no significant increase of density at 1400oC. The Vickers hardness of HAp showed increasing trend for temperature range of 1000oC to 1100oC with the compacts attaining HV of ~7 GPa at 1100oC. Subsequently, the hardness decreased with increasing sintering temperature though the value does not dropped below ~5 GPa. Similarly, HAwm compacts showed an increasing trend from 1000oC to 1300oC with the largest HV attained was ~4.57 GPa. Further increased in sintering temperature resulted in the decreased of Vicker’s hardness. Moreover, the HAp samples reached a maximum fracture toughness of ~0.9 MPam1/2 at 1050oC while the HAwm attained maximum KIc of only ~0.7 MPam1/2 at 1300oC.

Abstract: Optimization of cutting parameters is one of the key obstacles for CAD/CAM integration. In this work optimum cutting parameters, the best sequence, number, and type of passes of turning operation are determined by Genetic Algorithm (GA). Proposed optimization strategy ensures that no constraint will be violated at the optimum condition and determines the optimum number and type of passes such as rough, finish and semi-finish passes to complete a multipass turning operation. Here objective function is the unit production cost and constraints are limits of cutting force, power, tool life, stability condition, tool chip interface temperature, surface finish, feed rate to depth of cut ratio and the available rotational speed of spindle of machine tool.

Abstract: Bulk of power transmitting metal gears of machinery is produced by machining processes from cast, forged or hot rolled blanks. It includes a number of versatile machining operations that use a milling cutter, a multi tooth tool to produce a variety of configurations. The aim of the computer aided process planning (CAPP) is to develop a programme for milling cutting processes. This paper reveals the hybrid approach to computer aided process planning for milling and grinding operations on gear blank, so that the plan can be generated taking into account the availability of machines and the material. The developed computer aided process plan has reduced the set up time and machining time by 40.90 and 30.15 % respectively.

Abstract: This paper was presented the finite element modeling, analysis and fatigue life prediction of lower suspension arm using the strain-life approach. Aluminum alloys are selected as a suspension arm materials. The structural model of the suspension arm was utilizing the Solid works. The finite element model and analysis were performed utilizing the finite element analysis code. TET10 mesh and maximum principal stress were considered in the linear static stress analysis and the critical location was considered at node (6017). From the fatigue analysis, Smith-Watson- Topper mean stress correction was conservative method when subjected to SAETRN loading, while Coffin-Manson model is applicable when subjected to SAESUS and SAEBRKT loading. From the material optimization, 7075-T6 aluminum alloy is suitable material of the suspension arm.

Abstract: The Computer Aided Design and Computer Aided Manufacturing are the modern innovative technology in garments manufacturing like all other manufacturing sectors. Garments CAD is specially used for pattern designing and marker making. On the other hand CAM is used for fabric cutting and other manufacturing sections. Before implementing those new technologies, manual system was widely used in garments sector. In recent time some large garments factories of Bangladesh are starting to adopt CAD and CAM technology. Beside that a huge number of medium and small size factories are using manual system yet. This paper presents a feasibility study of CAD and CAM technology in above mentioned different size factories in Bangladesh. The Study is carried out in respect of production procedure, required man power, production/hr, product quality, production efficiency, and production cost. The practical investigation and data shows the scenario that all types of garments industries are not capable to use CAD & CAM and also not even profitable for them.

Abstract: Spread of household air conditioning system is continued to be increased. Along with the spread, the acknowledgement on product quality by the customer is increasing. Therefore, not only basic performances like cooling and power consumption but also design and noise level of in-house and external unit become the important factors. Axial fan in the external unit of air conditioning system is for ventilation and air supplying unit, and the related products have been widely adopted as household electronics, automobile engine, big sized blower in factory, tunnel, and subway. In this study, commercial 3-winged propeller fan from S company is modified to 2-winged fan for the cost reduction. Using 3D modelling, the fan shape is modified, and analysis flow is adopted to provide the way to reduce cost while maintaining the same wind capacity.

Abstract: In this study, a mathematical model was developed to simulate 2-D axisymmetric melt flow under magnetic field in a cylindrical container. The modeling of this process required the simultaneous solution of the turbulent Navier-Stokes equations together with Maxwell equations. The flow pattern in liquid bath was obtained using a two-equation κ-є turbulent flow model, which was further used to obtain the solute distribution. The governing differential equations were solved numerically using finite volume based finite difference method. The computed results, were found to be in good agreement with the measurements reported in the literature. The effect of stirring parameters on temperature homogeneity of the melt have been discussed and presented.

Abstract: Concave/convex wall features are usually generated in the deep-drawn parts with complicated geometry, especially the difficult-to-deep draw materials. The application of the draw bead could reduce the concave/convex wall features. However, it is difficult to determine the suitable draw bead geometry and its position to obtain a straight wall. In this study, the effects of draw bead height were investigated using the finite element method (FEM) and experiments. The application of the draw bead and the effects of its height on the concave/convex wall features could be theoretically clarified on the basis of principal stress distribution. The application of draw bead led to the decrease in tensile stress in the direction of punch movement and also increased in the tensile stress distributed to the corner zone; therefore, the concave wall feature decreased. In addition, this feature decreased as the draw bead height increased. However, the application of a very large draw bead height resulted in a convex feature. The FEM simulation results were validated by experiments in the following two cases, i.e., without and with draw bead formations. With reference to the material thickness distribution, the FEM simulation results showed a good agreement with experimental results.

Abstract: This paper describes the development of computer model used to characterize the heat transfer properties of the laser sealed advanced zirconia based ceramic coating. The model is built using ANSYS (11) software where all the environments simulated to be similar to the experimental environments. According to experiments dealed with the same data the temperature cant be reading since it is difficult to be fast enough as the changes occurs due to small interaction time .The temperature profile was recorded with each traverse velocity, the temperature changes with time and velocity were recorded too.