1.2. Matmodlab Conventions¶

Overview¶

Conventions used throught Matmodlab are described

Dimension¶

Material models are always called with full 3D tensors.

Vector Storage¶

Vector components are stored as

$\Tensor{v}{}{}{} = \{v_x, v_y, v_z\}$

Tensor Storage¶

In general, second-order symmetric tensors are stored as 6x1 arrays with the following ordering

(1) $\AA = \{A_{xx}, A_{yy}, A_{zz}, A_{xy}, A_{yz}, A_{xz}\}$

Tensor components are used for all second-order symmetric tensors.

Nonsymmetric, second-order tensors are stored as 9x1 arrays in row major ordering, i.e.,

$\BB = \{A_{xx}, A_{xy}, A_{xz}, A_{yx}, A_{yy}, A_{yz}, A_{zx}, A_{zy}, A_{zz}\}$

Note

The tensor order is runtime configurable using ordering keyword to the MaterialModel constructor. See Invoking User Materials for details.

Engineering Strains¶

The shear components of strain-like tensors are sent to the material model as engineering strains, i.e.

$\Strain = \{\epsilon_{xx}, \epsilon_{yy}, \epsilon_{zz}, 2\epsilon_{xy}, 2\epsilon_{xz}, 2\epsilon_{yz}\} = \{\epsilon_{xx}, \epsilon_{yy}, \epsilon_{zz}, \gamma_{xy}, \gamma_{xz}, \gamma_{yz}\}$

matmodlab Namespace¶

Input scripts to Matmodlab should include:

from matmodlab import *

to populate the script’s namespace with Matmodlab specific parameters and methods.

Parameters¶

Some useful parameters exposed by importing matmodlab are

ROOT_D, the root matmodlab directory
PKG_D, the matmodlab/lib directory, the location shared objects are copied
MAT_D, the directory where builtin materials are contained

Methods¶

Some useful methods exposed by importing matmodlab are

MaterialPointSimulator, the material point simulator constructor
Permutator, the permutator constructor
Optimizer, the optimizer constructor

Each of these methods is described in more detail in the following sections.

Symbolic Constants¶

The following symbolic constants are exposed by importing matmodlab:

XX, YY, ZZ, XY, YZ, XZ, constants representing the xx, yy, zz, xy, yz, and xz components of second-order symmetric tensors.