| Summary: | 碩士 === 國立中興大學 === 生物產業機電工作學系 === 91 === This study aims to use the non-destructive test to investigate the correlations between signal of the sensor response and the cracks, the thickness and the number of pores of the eggshell. Based on those basic data, the eggshell quality inspection system could be set up in the future. First, in this research, the basic physical properties of the egg including the shape coefficient, the thickness and the number of pores of the eggshell were measured; and then using two kinds of sensors, the eggshell quality inspector and accelerometer, to knock slightly on the surface of the eggshell, the impulsive time response were recorded.
The experimental results showed that the thickness of the eggshell and the contact time during impact had well correlation ( ) in the negative, which meant that the thicker eggshell, the shorter contact time. Consequently, referring to the time response, it is possible to estimate the average thickness of the eggshell. However, the pores were non-uniformly distributed on the eggshell resulting lower correlation between the contact time and the number of the pores.
By measuring the eggshell thickness, it was observed that the sharp top of the eggshell was thicker than other places. Under 95﹪confidence interval, there were no significant difference between the thickness at the place near the equator and the blunt end. Assume that the thickness of the eggshell was almost the same; it was found that the contact time on sharp top, and on the equator and blunt end of the eggs were significantly different. Based upon Hertz contact theory as well as impact theory, it showed that, for the eggshells without cracks, the larger of the radius of curvature, the longer of the contact time. It meant that the impulsive contact time on the blunt end was shorter than on the equator, and was longer than on sharp top. For the eggshell with crack, the contact time decreased due to the lower Young’s modulus around the cracks.
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