In the element description for SHELL181, we state that real constants 7-12 (transverse shear stiffnesses, drill stiffness, membrane and bending HG control factors) have program-provided default values. What are the defaults values?
The nomenclature used for these real constants is as follows: direction 1 is the element x direction, and direction 2 is the element y direction.
The default for E11 is 5/6*GXZ*h. If there are layers, E11 is the sum of this quantity over the layers. GXZ (as well as GYZ and GXY) is either defaulted from the other properties in the isotropic case, or is explicitly input in the orthrotropic case.
E22 is similar.
E12 defaults to 0.0. E12 is 0.0 if all layer materials are isotropic, but is non-zero in the general case using orthotropic materials.
Real constant 10, 11, 12 all default to 1.0.
The drill stiffness factor = 0.005 * (real constant 10) * (maximum of E11 and E22)
The membrane hourglass factor = 0.01 * (real constant 11) * (maximum of E11 and E22) * (element size scaling)
The bending hourglass factor = 12.0 * (real constant 12) * (maximum of E11 and E22)* (element size scaling ) * (D(3,3)/A(3,3))