Ashish Khemka
Ansys Employee
akhemka posted this 17 minutes ago

 


From our database: We offer this for concrete modeling- TB,CONCR for use with only SOLID65: This is an old concrete model. It is only supported for SOLID65, an 8-node brick element. SOLID65 allows to model brittle behavior of concrete/rock. Basically, when the stress state hits the failure surface, we lose stiffness completely at the integration point. Hence, think of this as a failure/damage model (where damage=100%). This model separates "cracking" and "crushing" behavior - if an integration point 'cracks', it loses stiffness completely in that direction only in tension, but it can 'close' the crack as well. If the integration point undergoes crushing, it loses stiffness completely in all directions.

TB,MPLANE is the microplane model, supported by current-technology planar (plane strain and axisymmetry only) and solid elements. The failure surface for the microplane model is a bit different from the concrete model noted above - it also does not differentiate between 'crushing' and 'cracking'. Instead of instantly losing 100% stiffness, this is a gradual damage model, so it helps with convergence (TB,CONCR can be harder to converge since we lose 100% stiffness when failure surface is reached; with microplane model, the stiffness loss is a bit more gradual). TB,MPLANE can also be used to model rock and concrete (lower tensile stiffness than compressive).

Reinforcements - discrete or smeared - can be included with REINF26x elements.
TB,EDP is the Drucker-Prager model that can look at the inelastic behavior of soils or rocks. This is a plasticity model, so it doesn't model cracking/crushing or damage. Instead, it is used to model the inelastic volume change and shearing of soils/rocks. The Cap model is useful since it provides a yield surface for triaxial compression, too.

As you can see, we really have two ways of modeling rock/concrete - if you are looking at the brittle failure, you would look at TB,CONCR or TB,MPLANE. On the other hand, if you wanted to look at the inelastic response prior to brittle failure, you would use TB,EDP.

We also have a porous media model for looking at soil consolidation problems (CPT21x elements), although they currently do not support nonlinear inelastic material models.