J2CyclicBoundingSurfaceMaterial

A material model that implements the J2 Cyclic Bounding Surface plasticity model, useful for modeling cyclical response in soil and other materials with complex hardening behavior.

Parameters:

Parameter	Description	Type
G	Shear modulus (required)	float
K	Bulk modulus (required)	float
Su	Undrained shear strength (required)	float
Den	Mass density (required)	float
h	Hardening parameter (required)	float
m	Hardening exponent (required)	float
h0	Initial hardening parameter (required)	float
chi	Initial damping (viscous). chi = 2*dr_o/omega (dr_o = damping ratio at zero strain, omega = angular frequency) (required)	float
beta	Integration variable (0 = explicit, 1 = implicit, 0.5 = midpoint rule) (default = 0.5)	float

Example

# Direct creation
from femora.components.Material.materialsOpenSees import J2CyclicBoundingSurfaceMaterial
j2_material = J2CyclicBoundingSurfaceMaterial(
    user_name="Clay",
    G=1.3e6,       # Shear modulus (Pa)
    K=2.6e6,       # Bulk modulus (Pa)
    Su=18000,      # Undrained shear strength (Pa)
    Den=1800,      # Mass density (kg/m³)
    h=1.5,         # Hardening parameter
    m=0.6,         # Hardening exponent
    h0=0.5,        # Initial hardening parameter
    chi=0.1,       # Initial damping
    beta=0.5       # Integration variable (midpoint rule)
)

or

# Via Femora
import femora as fm

fm.material.create_material(
    material_category="nDMaterial",
    material_type="J2CyclicBoundingSurface",
    user_name="Clay",
    G=1.3e6,
    K=2.6e6,
    Su=18000,
    Den=1800,
    h=1.5,
    m=0.6,
    h0=0.5,
    chi=0.1
)