The Section Stiffness material model provides a way of directly entering the stiffness or compliance of a shell without direct knowledge about the cross section thickness and material distribution. It main purpose is for entering homogenized properties of for example perforated or corrugated sheets.
By adding the following subnodes to the Section Stiffness node you can incorporate other effects:
From the Specify list, select
Effective stiffness or
Effective flexibility in order to specify the representation of the section stiffness.
If required, enter also the Translational inertia,
I0;
Rotational-translational inertia matrix,
I1; and
Rotational inertia matrix,
I2. The translational inertia is the average mass per unit area. As long as the shell is not thick or shear flexible, the two latter contributions to the inertia can usually be ignored. If the mass distribution of the shell is symmetric with respect to the midplane, then
I1 is identically zero.
The default for all section properties is to take the values From material. Any one of the matrices can also be
User defined.
Enter an In-plane force factor, S
N. This is a matrix which transforms the local membrane force (N
11, N
22, N
12) into a local in-plane stress (s
11, s
22, s
12).
Enter a Moment factor, S
M. This is a matrix which transforms the local bending moment (M
11, M
22, M
12) into a local in-plane stress (s
11, s
22, s
12).
Enter an Out-of-plane force factor, S
Q. This is a matrix which transforms the local shear force (Q
1, Q
2) into a local transverse shear stress (s
13, s
23).
