1. Discretization

1.1. Degrees of freedom

Modeling	Degrees of Freedom (at each vertex node)
AXIS_SI	DX: corresponds to the radial displacement DY: corresponds to the longitudinal displacement
D_ PLAN_SI	DX: next move \(X\) DY: next move \(Y\)
C_ PLAN_SI	DX: next move \(X\) DY: next move \(Y\)

1.2. Support mesh for stiffness matrices

The support cells for finite elements can be triangles or quadrangles. The elements are iso-parametric. Only the element based on mesh QUAD8 is under-integrated.

Models	Mesh	Interpolation	integration
AXIS_SI D_ PLAN_SI C_ PLAN_SI	TRIA3 QUAD4 TRIA6 QUAD8 QUAD9	Linear Bi-linear Quadratic Serendip Bi-Quadratic	complete Reduced completes Reduced complete

1.3. Cargo support mesh

Models	Mesh	Interpolation
AXIS_SI D_ PLAN_SI C_ PLAN_SI	SEG2 SEG3	Linear or Quadratic