Optimization of rotational magnetized direction permanent magnet thrust bearing configuration is carried out using generalized three-dimensional mathematical model. The bearing features namely axial force and stiffness are maximized using in-house developed mathematical expressions solved using MATLAB. The design variables selected for the optimization are axial offset, number of ring pairs, air gap and inner radius of inner and outer rings. The maximized axial force values of the optimized configuration are validated with the finite element analysis results. To overcome the high computational cost associated with three-dimensional equations, generalized method of optimization is sucessfully demonstrated using plots representing variation of optimal design variables as a function of air gap with respect to bearing’s outer diameter. Simple and useful method of using the generalized plots for the process of optimization is presented by dimension optimization of representative bearing configuration with a particular aspect ratio. The proposed optimization using mathematical model and generalized approach assists designer in selecting optimized geometrical parameters of rotational magnetized direction thrust bearing configurations easily for variety of high-speed applications.
Aluminum (A356)-SiC metal matrix composites were fabricated by using liquid metallurgy route. To improve the interfacial bonding between the Al and SiC, an attempt has been made to coat the SiC particles with Ni and Cu. Electroless process was used for coating the reinforced particle. This surface modification due to electroless coating on SiC particles was confirmed with SEM/ EDS analysis. Processing parameters such as melt temperature, stirring speed, stirring time, and preheating temperature were optimized. SiC content in Al-SiC MMC were taken from 5 to 15% and effect of Ni and Cu coating was studied using hardness measurements. Influence of coated SiC particles in Al-SiC showed significant improvement in hardness values. Moreover, micro structural examination clearly demonstrated that Cu coating on SiC particles resulted in good metallurgical boding as compared to SiC particles with Ni coating. As a result, the hardness values of Al-SiC (Cu) exhibited better hardness values as compared to Al-SiC (Ni) MMCs. As expected, high SiC content in types of Al-SiC MMCs showed high hardness values as compared to low SiC content and base alloy. The present investigation suggests that Cu coating on SiC particles are more suitable as compared to Ni coating on SiC particles to synthesis Al-SiC MMCs.
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