Measuring the mechanical stiffness of an eggshell using resonant frequencyanalysis

1. A new method was introduced for the measurement of mechanical eggshell c haracteristics based on the analysis of the vibration response of a chicken egg excited with a non-destructive impact. Four major topics were examined . 2. The 3 dimensional vibration pattern of an intact chicken egg was describ ed for the spherical vibration with the lowest resonant frequency. 3. The resonant frequency of this basic vibration mode and the total egg ma ss were used to calculate a dynamic stiffness value of the eggshell based o n a mathematical mass-spring model. 4. A correlation analysis between this dynamic stiffness value and several common egg and eggshell variable was calculated. Pearson correlation coeffi cients between the dynamic stiffness and static stiffness, eggshell thickne ss at the equator, eggshell width and shape index were all significantly di fferent from zero and were 0.71, 0.60, 0.43 and 0.51, respectively. 5. Graphical analysis of the static vs the dynamic eggshell stiffness indic ated that eggs with thick shells (>360 mu m) had a higher static stiffness value than the dynamic stiffness measurement, whereas the static stiffness of eggs with thin shells (>300 mu m) was lower than the dynamic stiffness. 6. The new vibration test method is a promising alternative for evaluating mechanical eggshell properties because of its non-destructive nature and br ief measuring time.