drucker_prager

drucker_prager

Drucker-Prager plasticity model for OpenSees nD materials.

Attributes

__all__ module-attribute

__all__ = ['DruckerPragerMaterial']

Classes

Material

Material(material_type: str, material_name: str, user_name: str)

Bases: ABC

Abstract base class for manager-owned OpenSees material objects.

Material instances do not self-register and do not assign their own tags. A :class:~femora.core.material_manager.MaterialManager owns lifecycle operations, tag assignment, removal, and retagging for a local model context.

Parameters:

Name	Type	Description	Default
material_type	str	OpenSees material category (e.g. 'nDMaterial').	required
material_name	str	Concrete OpenSees material name (e.g. 'ElasticIsotropic').	required
user_name	str	User-specified label for this material instance.	required

Attributes:

Name	Type	Description
tag	Optional[int]	Manager-assigned OpenSees material tag. Remains None until this object is added to a :class:~femora.core.material_manager.MaterialManager.
_owner	object | None	Reference to the owning manager, or None when unmanaged.

Methods:

to_tcl abstractmethod

to_tcl() -> str

Render the OpenSees material definition command as a Tcl string.

updateMaterialStage

updateMaterialStage(state: str) -> str

Return an updateMaterialStage Tcl command, or empty string.

set_parameter

set_parameter(parameter_name: str, new_value: Union[float, int, str, None] = None, element_tags: Optional[List[int]] = None) -> str

Return a setParameter Tcl command, or empty string.

get_param

get_param(key: str) -> Any

Return the value of a stored parameter by key.

DruckerPragerMaterial

DruckerPragerMaterial(user_name: str = 'Unnamed', *, k: float | None = None, G: float | None = None, sigmaY: float | None = None, rho: float | None = None, rhoBar: float | None = None, Kinf: float | None = None, Ko: float | None = None, delta1: float | None = None, delta2: float | None = None, H: float | None = None, theta: float | None = None, density: float | None = None, atmPressure: float | None = None, **_: Any)

Bases: Material

Pressure-sensitive elastoplastic solid with combined isotropic and kinematic hardening.

Maps to OpenSees DruckerPrager as an nDMaterial. The required arguments k, G, sigmaY, and rho correspond to the Tcl command slots for bulk modulus, shear modulus, initial yield intercept, and the material cohesion-like strength parameter rho. In this model, rho is not mass density; use density for mass density effects.

Tcl form

nDMaterial DruckerPrager <tag> k G sigmaY rho rhoBar Kinf Ko delta1 delta2 H theta density atmPressure; #

Note

• rhoBar is constrained to [0, rho] by the current validation rules.
• Coordinate atmPressure and density units with the bulk and shear modulus units used in the exported model.

Attributes:

Name	Type	Description
params		All validated Tcl arguments keyed by parameter name.

Example

from femora.core.model import Model

model = Model()
mat = model.material.nd.drucker_prager(
    user_name="dp_solid",
    k=2.0e5,
    G=9.6e4,
    sigmaY=2.5e3,
    rho=1.85,
    density=2100.0,
)
print(mat.tag)

Create a Drucker-Prager material object with validated inputs.

Parameters:

Name	Type	Description	Default
user_name	str	Stored in Tcl suffix comments and enforced unique among managed materials.	'Unnamed'
k	float | None	Bulk modulus analogue in the Tcl command, strictly greater than zero.	None
G	float | None	Shear modulus analogue in the Tcl command, strictly greater than zero.	None
sigmaY	float | None	Initial yield intercept, strictly positive.	None
rho	float | None	Cohesion-like Drucker-Prager strength parameter, strictly positive.	None
rhoBar	float | None	Optional cap on dilatancy evolution. Defaults to rho and must satisfy 0 <= rhoBar <= rho.	None
Kinf	float | None	Optional long-run isotropic strengthening magnitude, >= 0.	None
Ko	float | None	Additional isotropic evolution parameter, >= 0.	None
delta1	float | None	Isotropic modulus expansion coefficient, >= 0.	None
delta2	float | None	Softening or decay coefficient, >= 0.	None
H	float | None	Combined hardening modulus, >= 0.	None
theta	float | None	Blend in [0, 1] between isotropic and kinematic mechanisms.	None
density	float | None	Optional mass density, >= 0.	None
atmPressure	float | None	Reference pressure for modulus updates, >= 0.	None
**_	Any	Unused keyword placeholders for forward compatibility.	{}

Raises:

Type	Description
ValueError	If a required parameter is missing.
ValueError	If a numeric value cannot be converted to float.
ValueError	If any validated value falls outside the supported interval.

Methods:

to_tcl

to_tcl() -> str

Serialize this component as an OpenSees Tcl command.

Returns:

Name	Type	Description
str	str	A single Tcl command string for this material, listing ``k G
	str	sigmaY rhoplus the optional hardening tail ending indensity``
	str	and atmPressure.

Raises:

Type	Description
ValueError	If the material lacks a manager-assigned tag.