Establishment of Vibration and Sound Quality Inspection Methods for Cooling Fans

• Main Authors: cheng yu hong, 洪振毓
• Other Authors: bor-tsuen wang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/18912425216347405728

碩士 === 國立屏東科技大學 === 機械工程系 === 89 === This work is to establish vibration and sound quality inspection methods for cooling fans. Upon the assumption that the cooling fan vibration is mainly induced by the unbalance mass effect, this work proposes a cantilever beam model to indirectly measure the acceleration response. By the finite element analysis, the analytical model for the cantilever beam with fan at the free end can be constructed and verified through experimental modal testing. The product of the unbalance mass and its eccentric radius can be obtained with the knowledge of system frequency response function and the measured acceleration. This unbalance mass effect is independent of excitation frequency, i.e., rotation speed, and can be used as a quality index to evaluate the cooling fan. Results show the proposed method is feasible in predicting the vibration quality of the cooling fan. The emitted sound spectra of the cooling fans are also measured. Nine noise indices are established to quantify the sound quality of cooling fans. Experimental results show that index B is most suitable and other indices can also be incorporated for practical sound quality inspection. Finally a standard procedure in developing inspection criterion for sound and vibration quality is also introduced and applicable to on-line inspection.