Shell, a naturally engineered egg packaging: Estimated for strength by non-destructive testing for elastic deformation

Abstract

Eggshell is a naturally engineered packaging of its interior content and prediction of the egg fracture force ( F ) under non-destructive elastic shell deformation ( D ) remains a challenge. Specifically, since shell deflection function under a constant load is linear, it is difficult to calculate the maximum point for F and the respective value of D . The aim was to solve this problem experimentally by employing a measurement instrument commonly used to analyse the deformation of metals and alloys. The experiments were conducted on chicken eggs aligned in their morphological parameters. A curvilinear characteristic of the change in the function F = f ( D ), was achieved at extremely low shell compression speeds (0.010–0.065 mm s −1 ). This enabled us to (i) describe the obtained functions accurately with Gaussian curves; (ii) expand the range of non-destructive load on a chicken egg to 30 N; and (iii) develop empirical equations for a reasonably accurate prediction of maximum shell deformation ( R 2 = 0.906) and shell strength ( R 2 ≈ 1). It is suggested that it is possible to calculate shell strength by measuring its deformation at five points that corresponded to non-destructive loads of 10, 15, 20, 25 and 30 N. The methodological approach proposed can be used for the development of an effective shell strength calculation procedure by non-destructive testing. It depends on the appropriate tool for assessing and controlling the elastic shell deformation as well as the features of strength properties of the studied eggs. • A curvilinear function of egg fracture force on elastic shell deformation derived. • Dependences were considered for non-destructive prediction of shell strength. • Equation for egg fracture force was inferred from 5 values of elastic deformation.