Orthotropy

Examples include fiber-reinforced plastics, trapezoidal sheets, reinforced concrete, and timber. As a rule, the Hooke's material law ($\mathrm\nu\;=\;\frac{\mathrm E}{2\;\cdot\;\mathrm G}\;-\;1\;\leq\;0.5$) is not valid for orthotropic materials anymore.

Material Parameters

For a 2D shell element, the material parameters are as follows:

• E_x stiffness in the local x-direction of the surface
• E_y stiffness in the local x-direction of the surface
• G_xz shear stiffness in the local x-direction of the surface
• G_yz shear stiffness in the local y-direction of the surface
• G_xy shear stiffness in the wall plane