Applied Mechanics and Materials Vol. 787

Abstract: Centrifugal pumps are widely used in industry and also domestically. It is commonly used for its robust design and its efficiency. Every machine has to be monitored periodically in order to maintain its efficiency and also to avoid unexpected failure which lead to loss of efficiency. So fault diagnosis is necessary to monitor the pump periodically for finding out the defects in pump and to replace it if necessary. Dismantling and assembling of pumps during fault diagnosis is a tedious process, vibration analysis can be helpful to monitor the performance of the pump system without dismantling. For the experimentation purpose mono-block centrifugal pumps have been used in this work. By using the Lab VIEW program and DAQ card as an interface, amplitude and frequency of vibration is obtained at different axes of the pump with the help of an accelerometer. Then the vibration spectrum is analyzed and defects are pointed out by identifying the frequency at which the amplitude of vibration is above the danger limit. The defects such as unbalance of impeller, bent shaft in pump, misalignment of shaft, hydraulic pulsation, cavitation and bearing defects are diagnosed using vibration data. The frequency at which different defects are occurring has been founded out by means of experimentation in the centrifugal pumps. Thus by diagnosing centrifugal pump using vibration data reduces cost and time for periodical maintenance. Shape memory alloy based ATDVA is used to control the amplitude of vibration due to hydraulic pulsation. Around 60% reduction in amplitude of vibration is evident for the varying excitation frequency between 336 Hz and 340 Hz due to hydraulic pulsation.

Abstract: Tool condition monitoring plays a huge role in the CNC machines in which it is used to avoid the breakage of the tools.In this paper area changed capacitive micro accelerometer is designed to measure the vibration exposure of the tool on various applications in the CNC machines. The design process and simulation of the Micro accelerometer are done using INTELLISUITE 8.6. The rectangular folded beamis designed to reduce the residual stress and to obtain a better sensitivity. Static and dynamic analysis shows that sensitivity of the designed capacitive accelerometer is good enough to detect the vibration of the tool.