Extraction of Mechanical Property Parameters Using Asymmetrical Structures

• Main Authors: Chen, wei-shen, 陳威伸
• Other Authors: Chen, kun-nan
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/23717400810481936915

碩士 === 東南技術學院 === 機電整合研究所 === 95 === ABSTRACT This research investigated the dynamics characteristics of symmetrical and asymmetrical structures, by combining the finite element analysis and modal testing results, and then used an optimization scheme to extract the mechanical properties of the structures under test. With the help of experimental modal testing and finite element analysis, two sets of natural frequencies and mode shapes of the structures could be obtained. Integrating both sets of natural frequencies into an optimization procedure and utilizing the ANSYS software to perform analysis and optimization, the structures’ Young’s modulus, Poisson’s ratio and shear modulus were extracted. For a comparison purpose, this research employed a symmetrical and an asymmetrical structure of two entirely different scales: one in millimeter scale and the other in micrometer scale. Conducting experimental modal testing on both structures, assorting the obtained frequencies, and updating the finite element models with the frequency information, the length of an error vector defined as the difference between analysis and experimental frequencies could be minimized. As for the symmetrical microcantilevers, only bending modes were able to be measured, and therefore the extraction of Poisson’s ratio performed poorly. As for the asymmetrical aluminum plates, the torsional modes were easily measured, and therefore the extraction of Poisson’s ratio achieved a very good result. In general, this research successfully employed an optimization scheme to extract structures’ mechanical properties proving the feasibility of the proposed procedure, and it provides an alternative choice for determining the mechanical properties of materials.