Finite element analysis of stresses during cooling of eggs with different physical characteristics

Maximum thermally induced stresses in eggshell under rapid cooling conditio ns were predicted using a validated axisymmetric finite element model (AFEM ). The maximum thermally induced stress in the eggshell occurred immediatel y upon cooling, i.e., after 1 s of rapid cooling (h = 2839.0 W/m(2)degrees C or 500 Btu/h-ft(2)-degrees F). For typical extra-large eggs, the AFEM cal culated eggshell stresses were 1.79 MPa (260 psi) and 1.73 MPa (251 psi) fo r meridional and circumferential directions, respectively. Maximum thermall y induced stresses occurred along the outer boundary at the interface betwe en air cell and albumen. Increasing eggshell thickness, air cell size, cool ing rate and the taper angle favored higher thermally induced stresses. Amo ng the ten test cases, Case 7 (M, THIN), which was a medium egg (the maximu m principal, i.e., pole to pole, dimension a = 28.5 mm (1.1 in.), minimum p rincipal dimension b = 21.2 mm (0.83 in.), taper angle theta = 5 degrees ai r cell size = 5% by volume) with thin eggshell (shell thickness, t = 0.305 mm (0.012 in.) under rapid cooling, experienced the smallest maximum therma lly induced stress (1.47 MPa or 214 psi). Consequently, an egg with these o r similar physical characteristic values is likely to have less damage due to stress-induced cracking during rapid cooling.