Mod-Ta-Ger¶

A fabric-extended Ta-Ger model. Mod-Ta-Ger inherits the full Ta-Ger formulation and adds three fabric parameters — zmax, cz and alpha — to improve the cyclic and dilatancy response. All Ta-Ger parameters and defaults carry over; the additional parameters default to zmax = 4, cz = 600, alpha = 13.

At a glance

Class: ACT.models.mod_ta_ger
numgeo name: Mod-Ta-Ger
Parameters with search bounds: 14
Imported as: from ACT.models import mod_ta_ger

Default parameter values¶

Mod-Ta-Ger inherits the Ta-Ger defaults and adds:

Parameter	Default
`zmax`	4
`cz`	600
`alpha`	13

Default search bounds¶

These are the built-in lower/upper bounds used when a parameter is optimized. Override any of them with set_bounds.

Parameter	Lower	Upper	Description
`G0`	1.	10000.	shear-modulus constant
`m`	0.3	1.0
`nu`	0.0	0.45	Poisson's ratio
`Q`	8.0	11.0
`R`	0.25	1.50	size of the elastic / intergranular-strain locus
`emin`	0.2	1.2	minimum void ratio
`emax`	0.3	1.6	maximum void ratio
`phics`	25.0	42.0	critical-state friction angle (degrees)
`delta`	0.0	5.0
`kappa`	0.6	1.0
`Gmodel`	1.0	2.0	shear-modulus model switch (1 or 2)
`zmax`	0.0	20.0	maximum fabric (dilatancy)
`cz`	1.0	5000.0	fabric-evolution parameter
`alpha`	0.0	30.0	pyknotropy / fabric exponent

Setting parameters¶

Assign initial / fixed parameter values with set(...):

from ACT.models import mod_ta_ger

model = mod_ta_ger()
model.set(G0=..., m=..., nu=..., Q=..., R=..., emin=...)

Full set signature

set(G0=None,m=None,nu=None,Q=None,R=None,emin=None,emax=None,phics=None,delta=None,kappa=None,Gmodel=None,zmax=None,cz=None,alpha=None,Kw=None)

Available set parameters: G0, m, nu, Q, R, emin, emax, phics, delta, kappa, Gmodel, zmax, cz, alpha, Kw.

Choosing free parameters¶

Narrow the search interval of selected parameters, then list the ones to optimize in globals.setup:

model.set_bounds(G0=[1., 10000.], m=[0.3, 1.0], nu=[0.0, 0.45], Q=[8.0, 11.0])
globals.setup(Model=model, Free_parameter=["G0", "m", "nu", "Q", "R", "emin"], ...)

Parameters that accept a set_bounds override: G0, m, nu, Q, R, emin, emax, phics, delta, kappa, Gmodel, zmax, cz, alpha.

Reading & updating single parameters¶

model.update("G0", value)   # set one parameter
x = model.get_parameter("G0")  # read one parameter

See the models overview for the common interface shared by all models, and Optimization for how the free parameters are searched.