# Element Library

Radioss element library contains elements for one, two or three dimensional problems.

Some new elements have been developed and implemented in recent versions. Most of them use the assumed strain method to avoid some locking problems. For the elements using reduced integration schema, the physical stabilization method is used to control efficiently the hourglass deformations. Another point in these new elements is the use of co-rotational coordinate system. For the new solid elements, as the assumed strains are often defined in the specific directions, the use of global system combined with Jaumman's stress derivation contributes to commutative error especially when solid undergoes large shear strains.

- Solid elements
- 8- and 20-node bricks, 4- and 10-node tetrahedrons
- Solid-shells
- 8- , 16- and 20-node hexahedrons, 6-node pentahedral element
- 2 dimensional elements
- 4-node quadrilaterals for plane strain and axisymmetrical analysis
- Shell elements
- 4-node quadrilaterals and 3-node triangles
- One dimensional elements
- rivet, springs, bar and beams

The implementation of these elements will now be detailed. Expression of nodal forces will be developed as, for explicit codes they represent the discretization of the momentum equations. Stiffness matrices, which are central to implicit finite element approaches, are not developed here.