Comparative Analysis of the Static and Dynamic Mechanical Eggshell Behaviour of a Chicken Egg

A chicken egg is an already packaged food. An important quality aspect of the packaging material is the mechanical strength of the eggshell. A commonly used technique for the measurement of the shell strength is the quasi-static, non-destructive compression of an egg between two parallel steel plates. The slope of the force-deformation curve is a measure for the stiffness of the shell and for the eggshell strength. However this method is tedious and the required equipment is expensive. An alternative method has been developed based on the vibration behaviour of the egg after impact excitation. A dynamic stiffness parameter, kdyn , is defined which is based on a mathematical mass-spring model of the dynamic behaviour of the egg. Moderate correlations are found between kstat and kdyn. A finite element model of the static and dynamic eggshell behaviour is developed in order to understand better the relationships between the two parameters. The influence of the different material and structural on the mechanical eggshell behaviour is analysed by performing a sensitivity analysis on each single parameter. These results are used to interprete the experimentally observed relationships.