Study the Feasibility of deriving the transfer function from the Rayleigh wave in the impact-echo displacement waveform

• Main Authors: Chieh-Hsiang Chang, 張翔傑
• Other Authors: C.C. Chen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/25np3m

碩士 === 朝陽科技大學 === 營建工程系碩士班 === 91 === Abstract This dissertation is a study for the feasibility of deriving the transfer function from the Rayleigh wave in the impact-echo displacement waveform. The peak amplitude of in impact-echo spectrum may be varied by the energy and the contact time produced by the impact force. The experimental result needs to be transformed into transfer function for quantitative evaluation. Because the contact time and amplitude of force can not be recorded by present instrumentation, the transfer function can not be calculated. We can only get the approximate transfer function from the simulated impact force derived by the Rayleigh wave. We first find the relation between maximum amplitude of R wave and of force. Then according to the established relation we can get the simulated impact force by dividing the R-wave by suitable coefficient. This study discusses the problem with two aspects. (1) Use finite-element models simulating the response of concrete plate to obtain the general formula that derived from amplitude of plate’s response and thickness of plate. (2) Study the difference between real experimental results and numerical results. Numerical models were established to study the effects of thickness of plate, contact time, and property of concrete to simulated transfer function. Use these results to derive a relation between amplitude of plate’s response and thickness of plate. In the experimental study, when the ratio between impactor-receiver distance and plate thickness is 0.1 and 0.2, the discrepancy between experimental and numerical result is 6％. The result shows the reliability of using the formula to predict the amplitude of the peak corresponding to plate-thickness in simulated transfer function.