Analyze ThII: Physical Nonlinearity

Hello,

I have a question regarding the Analyze ThII component.

From the documentation, I understand that the component performs a second-order analysis by iteratively updating the stiffness matrix according to the deformed geometry, which indicates that geometric nonlinearity is considered.

However, I could not find a clear statement regarding the consideration of physical (material) nonlinearity. Specifically, I would like to know whether the analysis also accounts for the nonlinear constitutive behavior of the material (e.g., cracking, stiffness degradation, yielding, or nonlinear stress–strain relationships), or whether the material is assumed to remain linearly elastic throughout the analysis.

In other words, does the Analyze ThII component consider:

  • Geometric nonlinearity only (updated geometry / P–Δ and P–δ effects with linear-elastic material); or
  • Both geometric and physical (material) nonlinearity?

If physical nonlinearity is not included, is there any recommended workflow within Karamba3D to incorporate both geometric and material nonlinear effects?

Thank you very much for your clarification.

Hello @Alice20,

As of Karamba3D version 3.1, only geometric nonlinearity is supported. Material (physical) nonlinearity is not currently included.
The Analyze ThII-component is limited to small displacements: it does not account for the increase in axia or in-plane foces in case of transverse displacements. For a rope with large displacements this means that the resultant displacement is overestimated and the normal force in the cable underestimated.
Unfortunately, there is currently no recommended workflow for including material non-linearity in Karamba3D.

-- Clemens