Building a model
Materials
Uniaxial and nD materials, and what "Used as" means.
Materials live in the Materials group. PySees offers the OpenSees uniaxial materials (about 75 types, such as Elastic, ElasticPP, Steel01, Steel02, Concrete01) and nD materials.
Materials in Carapace
Carapace, the in-browser solver, has its own implementations of the materials below. Whether you can run one from PySees depends on the last column.
| Material | Behaviour | Typical use | Runs in PySees |
|---|---|---|---|
| Elastic | Linear elastic, equal in tension and compression. Parameter: E. | Elastic members, springs | Yes |
| ElasticPP | Elastic–perfectly plastic with permanent set. Parameters: E, epsyP. | Simple yielding springs and steel | Yes |
| ENT | Elastic, no tension. Parameter: E. | Compression-only struts and soil | Yes |
| Steel01 | Bilinear steel with kinematic hardening b and optional isotropic hardening (a1–a4). | Reinforcing and structural steel fibers | Yes |
| Steel02 | Menegotto–Pinto steel with a smooth elastic-to-plastic transition (R0, cR1, cR2), hardening b and optional isotropic hardening. | Steel fibers where the Bauschinger effect matters | Yes |
| Concrete01 | Kent–Scott–Park compression envelope with degrading unloading and no tension. Parameters: fpc, epsc0, fpcu, epsU. | Concrete fibers (compression only) | Yes |
| Concrete02 | Concrete01 plus linear tension softening. Adds tensile strength ft and softening slope ets. | Concrete fibers where cracking and tension stiffening matter | Not yet |
| Hysteretic | Tri-linear backbone, different in each direction, with pinching and stiffness and strength degradation. Parameters: three (force, deformation) points per side, pinchX, pinchY, two damage factors and beta. | Moment–rotation and force–deformation springs | Not yet |
| Pinching4 | Four-point backbone per side with pinching and independent unloading-stiffness, reloading-stiffness and strength damage rules (energy- or cycle-based). | Detailed degrading springs, such as timber and masonry connections | Not yet |
| Gap | One-sided gap: stiff after the gap closes. Parameters: E, gap. | Contact and pounding springs | Not yet |
| Parallel, Series, MinMax | Combine other materials: share strain, share stress, or fail outside a strain range. | Composite behaviour, fracture limits | Not yet |
Some optional arguments are not passed to Carapace: epsyN and eps0 on ElasticPP (the yield strain is the same in both directions), and an initial stress on Steel02.
Creating a material
Choose the material type in the add box, or use New Material… from any material picker (for example inside the section editor). The New Material dialog shows the type's parameters, a live code preview, and these buttons: Preview, Reset, Cancel and Create. Parameter names follow the Carapace schema in lower case (fy, e0, epsU).
Used as
Every uniaxial material has a Used as setting, fixed when it is created and locked when you edit it:
- Stress–strain for fibers, patches, layers and trusses.
- Force–deformation for zero-length springs.
The setting decides whether parameters are shown as stresses and strains or as forces and deformations, and which pickers offer the material.
Previewing
Preview opens the material preview to check the behaviour before you use it.