| Summary: | 碩士 === 逢甲大學 === 土木及水利工程所 === 92 === The main purpose of this thesis is to establish a stress-wave velocity measuring system for standard cylindrical specimens in the laboratory for research in the future. The size of the specimen is 15cm in diameter and 30cm in height. Two kinds of materials have been tested including steel and concrete. The stress-wave is generated upon the bottom plane of the specimen by a steel ball and received by two vertical accelerometers which are located on the orthogonal side of the impact plane. The cross-correlation velocity is determined by cross-correlation function in time domain. In order to verify the correctness of the cross-correlation velocity obtained in this research, a ultrasonic thickness gage was used to measure the wave velocity of the steel specimen whereas a impact-echo system was used for the concrete specimen.
According to the experimental results, the testing arrangement parameters were suggested: the vertical distance of the impact Iy＝0.7cm, horizontal distance of the impact r=11cm, and distance between two receivers d=9cm. Also, the average value of four base lines from the specimen was suggested to represent the wave velocity of the specimen. Based on the arrangement parameters suggested aforementioned, the average of four lines to represent the velocity of the specimen. The average cross-correlation velocity of concrete cylinder is 3455 m/s, coefficient of variation is 1.975m/s. and the absolute error with impact-echo velocity is 0.8267％.
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