As technology advances, ANSYS, Inc. continues to develop robust new element types using the most current technologies available. Current-technology elements are more advanced and feature-rich than legacy elements. For example, support for the following capabilities is available only in applicable current-technology elements:
A vast array of material constitutive options (such as anisotropic hyperelasticity, cast iron plasticity, enhanced Drucker-Prager plasticity, Hill plasticity, hyperelasticity, shape memory alloy, plasticity, rate-dependent plasticity, viscoelasticity, and others).
Association of a single element with several material constitutive options (such as a combination of hyperelasticity and viscoelasticity with Prony series expansion).
Fracture mechanics parameter calculation (CINT), which uses the domain-integration approach to calculate the J-Integrals for both linear and elastoplastic material behavior at a designated tip location (2-D) or at specific location along the crack front (3-D) through a structure component.
Custom user-defined material models created via the
3-D smeared reinforcing, provided by elements such as REINF265 when used with 3-D solid and shell elements (referred to as the base elements) to achieve the effect of extra reinforcement to those elements.
Nonlinear stabilization, a viscous-based algorithm for improving convergence behavior when instabilities are expected.
Rezoning for solid elements.
Linear perturbation based on nonlinear analysis.
Precise control of the element technologies (ETCONTROL) used in element formulation for applicable elements.
A layered-section option (via SECDATA and other section commands) for shell and solid elements.
In Selecting Elements for Your Analysis, current-technology elements appear first. You can readily identify them, as they are not typically associated with specific material types, nor do they specify restrictions such as “linear.” Most of the elements listed are current-technology elements in the sense that they are the best technologies that ANSYS, Inc. is able to offer at the current product release.
A few legacy elements are still supported to meet the needs of longtime users who have input files containing those elements. Legacy elements may eventually be replaced by new elements.
It is good practice to use current-technology elements rather than legacy elements in your analysis wherever possible.
The following table lists the remaining legacy elements and suggests current-technology elements to use instead. In some cases, an element KEYOPT setting, degree-of-freedom constraint, or command may be necessary to more precisely reproduce the behavior of a given legacy element.
|Legacy Element Type ||Suggested Current Element Type ||Suggested Setting(s) to Approximate Legacy Element Behavior |
|PLANE25||SOLID272||KEYOPT(6) = 0|
|PLANE83||SOLID273||KEYOPT(6) = 0||---|
KEYOPT(3) = 0 and KEYOPT(2) = 0 -- Full integration with the method
KEYOPT(3) = 0 and KEYOPT(2) = 3 -- simplified enhanced strain formulation
|See Microplane in the .|
After considering element redundancy and consistency issues, ANSYS, Inc. may in future releases move legacy element documentation to the Feature Archive or undocument those elements altogether; however, the table does not imply that all legacy elements listed are immediate targets for such action.
The table is not a definitive listing of legacy-to-current element equivalents in terms of either formulation or use of shape functions; for example, a suggested current element may require a more refined mesh in some cases, or may require adaptation via appropriate constraints for specific 2-D analyses.
While a given KEYOPT setting can allow you to approximate the behavior of a legacy element, it may not be the most desirable KEYOPT for the current element. For structural-only analyses, try the ETCONTROL command for element and KEYOPT recommendations. For more information, see Automatic Selection of Element Technologies and Formulations.