Determination of mode shapes from ODS for beam structures

• Main Authors: WU YING-HUI, 吳盈輝
• Other Authors: 王柏村
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/96155669673762749723

碩士 === 國立屏東科技大學 === 機械工程系 === 90 === This work presents modal analysis of beam structure in operating conditions. In particular structure is in the harmonic excitation. the prediction model is developed to determine mode shapes from operational deflection shape (ODS). Both simply supported beam and cantilever beam are considered. Numerical simulation is performed to show the feasibility of the developed prediction model. Mode shapes can be well predicted. The harmonic response analysis is first presented. The ODS can be shown as function of modal parameters. Natural frequencies and damping ratios can be obtained from single measurement of frequency response function. Therefore, Experimental verification is also conducted for a cantilever beam. The ODS of beam is first measured for both on-resonance and off- resonance excitation cases. The prediction model can then employed to determine structure mode shapes. Results show that predicted mode shapes reasonably agree with the theoretical mode shapes. The developed methodology will be beneficial for structure modal analysis in operating condition. In Particular, This developed prediction model can be applied to rotor system in its operating condition.