Eggshell crack detection by dynamic frequency analysis

Abstract

Eggshell cracks were detected by the analysis of the dynamically measured frequency response wave of an egg excited with a light mechanical impact on different locations of the eggshell. As a result of the analysis, the dominant resonance frequency could be observed and the frequency value is lower in the intact eggs. For the cracked eggs, the same peak frequencies were found, the magnitudes of which were similar, and the values were higher. The resonance frequency domain and the dominant frequency are dependent on the relative position of the excitation point towards the location of the crack on the shell. The excitation resonance frequency characteristic of the cracked egg may be consistent with that of the intact egg, if the detection point is far from the position of the crack. Four variables were investigated to determine if they are significant for classifying eggs by setting up relationship x- and y-coordinates, including the first dominant resonance frequency, the normalization average of the frequency domain, the average of the frequency domain, and the average x- and y-coordinates of the centroid for the frequency domain. The dominant frequency, the average of the frequency domain or the normalization average of the frequency domain could be used for classifying the intact and cracked eggs, and the dominant frequency and the normalization average of the frequency domain were more precise than the others in the classification. Use of the first dominant frequency was the best method for detecting cracked eggs.