Did you know? In contrast to other material models, the stress-strain diagram for this material model is not antimetric to the origin. You can use this material model to simulate the behavior of steel fiber-reinforced concrete, for example. Further information about modeling steel fiber-reinforced concrete can be found in this technical article: KB | Determining Material Properties of Steel Fiber-Reinforced Concrete and Their Application in RFEM
In this material model, the isotropic stiffness is reduced with a scalar damage parameter. This damage parameter is determined from the stress curve defined in the Diagram. This does not take the direction of the principal stresses into account; rather, the damage occurs in the direction of the equivalent strain, which also covers the third direction perpendicular to the plane. The tension and compression areas of the stress tensor are treated separately. In this case, different damage parameters apply.
The "Reference element size" controls how the strain in the crack area is scaled to the length of the element. With the default value zero, no scaling is performed. Thus, the material behavior of the steel fiber-reinforced concrete is modeled realistically.
You can find the background information on the "Isotropic Damage" material model in this technical article: KB 001461 │ Nonlinear Material Model Damage .
