Numerical Analysis and Experiments of Hollow Cylindrical Structure with Impact-Echo Method

• Main Authors: Yen-Cheng Chen, 陳彥成
• Other Authors: Ta-Peng Chang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/25869p

碩士 === 國立臺灣科技大學 === 營建工程系 === 100 === The thesis uses the impact-echo experiment, guided-wave theory and numerical simulation to study the behavior of wave propagation of hollow cylinder. The experimental results are used to verify the correctness of the guided-wave theory and numerical simulation, which demonstrates that the instruments of impact echo method and numerical simulation can be used to detect the material properties and cross-section resonance frequencies of hollow cylinders with various materials, such as concrete, metal and plastic. In the meantime, the influences of the diameter, tube thickness and embedded depth of the hollow cylinders with different materials on the stress wave propagation were also investigated. First, the guided-wave theory was used to analyze the hollow cylinders with different kinds of material property, and the six cross-sectional resonance frequencies were compared with those from the numerical analysis of impact-echo method. The results show these two sets of resonance frequencies are quite close to each other. It indicates that the guided-wave theory can be applied to the hollow cylinders with any kind of single material. The given formula can deduce the ? values and the first to sixth cross-sectional resonance frequencies of the hollow cylinder with any single material. A simple table is thus established to quickly estimate the first to sixth cross-sectional resonance frequencies of various hollow cylinders with single material. For the composite hollow cylinders composed of different materials, only the numerical method is available to obtain the first six cross-sectional resonant frequencies. In order to investigate the effects of various parameters on the response from the numerical simulation, this study uses the variations of six parameters to analyze and discuss nine sets of combinations. The results show that a significant difference of the cross-sectional resonant frequencies occurs when the material property or the diameter is changed, but there is only a minor change if the tube thickness or embedded depth is changed.