Nonlinear Material Behavior | Isotropic | Damage (Surfaces/Solids)

The goal of using the RFEM 6 and Blender with the Bullet Constraints Builder add-on is to obtain a graphical representation of the collapse of a model based on real data of physical properties. RFEM 6 serves as the source of geometry and data for the simulation. This is another example of why it is important to maintain our programs as so-called BIM Open, in order to achieve collaboration across software domains.

Windbreak structures are special types of fabric structures which protect the environment from harmful chemical particles, abate wind erosion, and help to maintain valuable sources. RFEM and RWIND are used for wind-structure analysis as one-way fluid-structure interaction (FSI). This article demonstrates how to structural design windbreak structures using RFEM and RWIND.

Consideration of p-δ Second-Order Effects in RFEM 6 and RSTAB 9

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: 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 area of the stress tensor is 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 concrete is modeled realistically.

You can find the background information on the "Isotropic Damage" material model in this technical article: Nonlinear Material Model Damage .

Did you know? When unloading the structural component with a plastic material model, in contrast to the Isotropic | Nonlinear Elastic material model, the strain remains after it has been completely unloaded.

You can select three different definition types:

• Standard (definition of the equivalent stress under which the material plastifies)
• Bilinear (definition of the equivalent stress and strain hardening modulus)
• Stress-strain diagram: definition of polygonal stress-strain diagram
• Option to save / import the diagram
• Interface with MS Excel

If you release a structural component with a nonlinear elastic material again, the strain goes back on the same path. In contrast to the Isotropic|Plastic material model, there is no strain left when completely unloaded.

You can select three different definition types:

• Standard (definition of the equivalent stress under which the material plastifies)
• Bilinear (definition of the equivalent stress and strain hardening modulus)
• Stress-Strain Diagram:
• Definition of polygonal stress-strain diagram
• Option to save / import the diagram
• Interface with MS Excel

Background information about the orthotropic material model can be found in this technical article: Yield Laws in Isotropic Nonlinear Elastic Material Model .