mean(mean(shell.Sll11)) MPa "Second Piola-Kirchhoff stress, layer coordinate system, 11 component"
mean(mean(shell.Sll22)) MPa "Second Piola-Kirchhoff stress, layer coordinate system, 22 component"
mean(mean(shell.Sll12)) MPa "Second Piola-Kirchhoff stress, layer coordinate system, 12 component"