Applied Mechanics and Materials Vols. 110-116

Abstract: ZnO is a semiconductor with direct band gap that because of its optical and electronically properties has very interesting for researchers. Wide application of this compound in electronic and optic like piezoelectric transducer, gas sensor, optical waveguide, thin conductor layer and transparent, varistors, photocells, optical U.V. equipments and also variety medical applications with concerning its nature friendly cause that to find the economical method for mass production be concerned. During recent decay, many methods such as sol-gel, wet chemistry, CVD & MOCVD, hydrothermal methods and development process have been invented for ZnO production. The most common problems of these methods are complexity of production process, need to expensive equipments, need to expensive raw materials, need to exceedingly pressure and temperature etc. In this research with activation of Zn as the raw material, nanoparticles of ZnO has been product by a planetary mill and hydride action that this method has ability to extensile in industrial range.SEM investigations approve the nanosize of produced particles. Morphology of particles is more similar to hexagonal crystal structure. Process efficiency is 100 percent and x-ray diffraction (XRD) of resultant powder verifies this. After synthesis and characterization of ZnO nanopowder as one of its application, varistor was made and then electrical property of this part was evaluated.

Abstract: The method of Transient Electromagnetic(TEM) detection is widely applied to the field of coal mine and oil exploration. But since Transient Electromagnetic signal is a non-stationary , nonlinear , weak signal under the background of heavy noise , traditional method which is based on the signal superposition is only suited to the signal of the superficial layer , it can not fetch the weak signal of the deep layer. noise reduction of the transient electromagnetic weak signal under heavy noise based on power detection of EMD decomposition is presented in this paper. This method does not need prior information. Through the method, the transient electromagnetic weak signal under heavy noise is decomposed to several intrinsic mode functions. Then by power detection, the noise leading component is extracted and reduced .At last the transient electromagnetic weak signal is obtained adaptively. The example of this paper show: when the received TEM signal of deep layer is -30db SNR, This method can reduce the most of noise, obtain the transient electromagnetic weak signal which contains geological information, and improve the depth and accuracy of the TEM detection.

Abstract: A comprehensive numerical study on the natural convection in a hydrodynamically anisotropic as well as isotropic porous enclosure is presented, flow is induced by non uniform sinusoidal heating of the right wall of the enclosure. The principal directions of the permeability tensor has been taken oblique to the gravity vector. The spectral Element method has been adopted to solve numerically the governing differential equations by using the vorticity-stream-function approach. The results are presented in terms of stream function, temperature profile and Nusselt number. The result show that the maximum heat transfer takes place at y = 1.5 when N is odd.. Also, increasing media permeability, by changing K* = 1 to K* = 0.2, increases heat transfer rate at below and above right corner of the enclosure. Furthermore, for the all values of N, profiles of local Nusselt number (Nuy) in isotropic as well as anisotropic media are similar, but for even values of N differ slightly at N = 2.. In particular the present analysis shows that, different periodicity (N) of temperature boundary condition has the significant effect on the flow pattern and consequently on the local heat transfer phenomena.

Abstract: In 5-Axis Machining of impellers, interference problems with tool and neighboring surfaces often take place due to the narrow and deep gap between blades, so the problem of avoiding interference is very important. Also, because the efficiency of turbo machines can be maximized only when fluids smoothly flow due to the characteristics of the impeller, high quality of the machined surface is required. During 5-Axis machining of these impellers, the excessive local interference avoidance, necessary to avoid interference, leads to inconsistency of cutter posture, low quality of machined surface and increase of processing time. Therefore, in order to increase the efficiency of 5-Axis Machining of impellers, it is necessary to minimize the cutter posture changes and create a continuous tool path while avoiding interference. This study, by using an MC-space algorithm for interference avoidance and an MB-spline algorithm for continuous control, is intended to create a 5-Axis machining tool path with excellent surface quality and economic feasibility; finally, this study will verify the effectiveness of the suggested method through verification processing.

Abstract: In the turning of a shaft with a step of specified corner R, it is important whether the corner radiuses of the turning insert is the same as the specified corner R or lower than it. A turning tool with a large corner radius cannot adapt to cutting a shaft with a step of specified corner R. In this study, the surface roughness, cutting force, and tool wear were experimentally investigated in order to clarify the cutting performance of the turning insert with a three-arcs-shaped finishing edge. The machined surface of the insert with a three-arcs-shaped finishing edge was better than that of the normal insert. The wear progress of the insert with an arc-shaped finishing edge was slightly slower than that of the normal insert. The cutting force of the insert with an arc-shaped finishing edge was almost the same as that of the normal insert.

Abstract: For aircraft sheet metal parts digital cutting, this paper uses IDEF0 to structure a digital system integrated with unfolding module, nesting module, cutting path planning module and NC cutting module, then analyzes data organization and process of the system application. In the system, an algorithm for the development of a doubly curved surface onto a plane is adopted, NC cutting process-oriented nesting algorithm is presented and rules of cutter path planning is developed. Furthermore, application examples of key technologies (unfolding, nesting, path cutter planning) are demonstrated and indicate that the system can realize digital cutting for aircraft sheet metal parts quickly and precisely.

Abstract: In the present industrial scenario, quality control is a crucial factor for the success of an industry or an organization. Process capability is an important statistical quality tool for measuring the capability of an industrial operation. The paper aims at the process capability of a reaming operation in manufacturing of cylinder head in a leading motorcycle company. The process capability of the reaming operation can be reflected by measuring the quality characteristics of its machined component. For this purpose, adequate sampling of the lot has been considered, probability plots and histograms have been prepared and the performance indices have been computed that indicate the capacity of the process to manufacture a component efficiently. Based on the observations made and data analysis, it has been proved that this statistical process control technique not only helps in improving quality and productivity of an industrial operation but also helps in taking important managerial decisions in an organization.

Abstract: Electrochemical machining is one of the widely used non-traditional machining processes to machine complicated shapes for electrically conducting but difficult-to-machine materials such as superalloys, Ti-alloys, alloy steel, tool steel, stainless steel, etc. Use of optimal ECM process parameters can significantly reduce the ECM operating, tooling, and maintenance cost and will produce components of higher accuracy. This paper investigates the effect and parametric optimization of process parameters for Electrochemical machining of EN-31 steel using grey relation analysis. The process parameters considered are electrolyte concentration, feed rate and applied voltage and are optimized with considerations of multiple performance characteristics including material removal rate, overcut and cylindricity error. Analysis of variance is performed to get contribution of each parameter on the performance characteristics and it was observed that feed rate is the significant process parameter that affects the ECM robustness. The experimental results for the optimal setting show that there is considerable improvement in the process. The application of this technique converts the multi response variable to a single response Grey relational grade and, therefore, simplifies the optimization procedure.

Abstract: In this review, present day, the best versatile material Titanium alloy (Ti-6Al-4V) plays the most vital role in the manufacturing of aero engines as a base material. It has been observed that machining this type of alloys is the complicated tasks with optimum machining results. This research investigates the consequences of machining parameters by making use three types of technique: firstly, nitrogen gas technique; secondly, high pressure coolant (HPC); thirdly, cryogenic cooling technique as the coolant’s techniques compared to the normal coolant. Utilizing liquid nitrogen and gas nitrogen as a coolant will decrease friction, heat at the cutting zone, surface roughness, the amount of power consumed in a metal cutting process in addition significantly increase the tool life, dimensional accuracy and so improve the productivity.

Abstract: The present work deals with the heat transfer analysis of pin fins of various geometries namely ─ circular, triangular and rectangular and thus arrive at the optimum design. To this end, the fin with convective boundary tip is considered and the equation governing the one-dimensional heat conduction in the fin is solved analytically to obtain the temperature distribution and heat transfer rate. A computer code has been developed to generate results for wide range of parameters─ heat transfer coefficient h, thermal conductivity k, and length of the fin l. Results are plotted in the form of temperature variation, heat transfer variation and optimum length variation. From the detailed discussion of the results it can be concluded optimum length decreases with increasing heat transfer coefficient and it increases with increasing thermal conductivity. It can be also concluded that the optimum length is minimum for a triangular fin compared to rectangular and circular fins.