🔗Uniaxial

A UniaxialMaterial describes a 1D stress–strain relationship, typically used for fibers, hinges, or simplified member behavior where only one force component is relevant (axial, shear or bending). In Alpaca4d the Uniaxial Grasshopper component is a switcher that exposes different uniaxial models (e.g. UniaxialElastic, ElasticPerfectlyPlastic).

At the moment, the main implemented model is UniaxialElastic, which creates an Alpaca4d.Material.UniaxialMaterialElastic object.

UniaxialElastic

The UniaxialElastic sub‑component defines a linear elastic uniaxial material:

• Material Name (optional): Custom name for the material (e.g. "Steel S235 – axial").

• E: Young’s modulus ([Force/Length²]) in tension.

• Eneg: Young’s modulus ([Force/Length²]) in compression (can be equal to E or different if needed).

• Eta: Viscous damping parameter (Rayleigh‑type), usually 0.0 for purely elastic behavior.

• G: Shear modulus ([Force/Length²]).

• ν: Poisson’s ratio.

• Rho: Density ([Mass/Length³]).

Output

• Material: A uniaxial material that can be assigned to elements or sections that expect a UniaxialMaterial.

ElasticPerfectlyPlastic (preview)

An ElasticPerfectlyPlastic uniaxial model is also available in the menu, but is currently marked as “not yet implemented” and only issues a warning. For now, use UniaxialElastic (or database‑based materials) for production models.

Usage notes

• Uniaxial materials are most commonly used in fiber sections and non‑linear hinges.

• You can combine several uniaxial materials in a section to represent different materials (steel, concrete, reinforcement) in the same cross‑section.

• For standard elastic behavior, you can also generate equivalent uniaxial materials directly from the Material Database (see below).