|Matrix or Vector||Geometry||Shape Functions||Integration Points|
|Stiffness and Stress Stiffness Matrices; and Thermal Load Vector||Quad||Equation 11–120 and Equation 11–121||
2 x 2 if KEYOPT(1) = 0, 2, or 3
|Triangle||Equation 11–100 and Equation 11–101||1|
|Mass Matrix||Quad||Same as stiffness matrix||2 x 2|
|Pressure Load Vector||Same as stiffness matrix, specialized to face||2|
|Element Temperature||Bilinear across element, constant thru thickness or around circumference|
|Nodal Temperature||Same as element temperature distribution|
|Pressure||Linear along each face|
Structures describes the derivation of structural element matrices and load vectors as well as stress evaluations. General Element Formulations gives the general element formulations used by this element.
If KEYOPT(1) = 1, the uniform reduced integration technique (Flanagan and Belytschko()) is used.
If KEYOPT(1) = 2 or 3, the enhanced strain formulations from the work of Simo and Rifai(), Simo and Armero(), Simo et al.(), Andelfinger and Ramm(), and Nagtegaal and Fox() are used. It introduces 5 internal degrees of freedom to prevent shear and volumetric locking for KEYOPT(1) = 2, and 4 internal degrees of freedom to prevent shear locking for KEYOPT(1) = 3. If mixed u-P formulation is employed with the enhanced strain formulations, only 4 degrees of freedom for overcoming shear locking are activated.