Cast Iron Plasticity

The cast iron plasticity model:

provides elastic-plastic behavior with different yield strengths, flow, and hardening in tension and compression;
is based on a yield function that depends on the maximum principal stress under tensile loading conditions and pressure-independent (von Mises type) behavior under compressive loading conditions;
allows for simultaneous inelastic dilatation and inelastic shearing under tensile loading conditions;
allows only inelastic shearing under compressive loading conditions;
is intended for the simulation of material response only under essentially monotonic loading conditions; and
cannot be used to model rate dependence.

Cast Iron Plasticity

The cast iron plasticity model describes the mechanical behavior of gray cast iron, a material with a microstructure consisting of a distribution of graphite flakes in a steel matrix. In tension the graphite flakes act as stress concentrators, resulting in yielding as a function of the maximum principal stress, followed by brittle behavior. In compression the graphite flakes do not have an appreciable effect on the macroscopic response, resulting in a ductile behavior similar to that of many steels.

You specify the elastic part of the response separately; only linear isotropic elasticity can be used (see Introduction to Linear Elasticity.)

The cast iron plasticity model is used to provide the value of the plastic “Poisson's ratio,” which is the absolute value of the ratio of the transverse to the longitudinal plastic strain under uniaxial tension. The plastic Poisson's ratio can vary with the plastic deformation. However, the model assumes that it is constant with respect to plastic deformation. It can depend on temperature and field variables.


Input Data	Description
Plastic Poisson's Ratio	Value of the plastic "Poisson's ratio," $ν_{p l}$ , where $- 1.0 \leq ν_{p l} \leq 0.5$ . (Dimensionless.)
Use temperature-dependent data	Specifies material parameters that depend on temperature. A Temperature field appears in the data table. For more information, see Specifying Material Data as a Function of Temperature and Independent Field Variables.
Number of field variables	Specify material parameters that depend on field variables. Field columns appear in the data table for each field variable you add. For more information, see Specifying Material Data as a Function of Temperature and Independent Field Variables.

Compression Hardening

Compression hardening data include the yield stress in compression and the corresponding plastic strain.


Input Data	Description
Sigma C	Yield stress in compression, $σ_{c}$ .
Epsilon C	Absolute value of the corresponding plastic strain. (The first tabular value entered must always be zero.)
Use temperature-dependent data	Specifies material parameters that depend on temperature. A Temperature field appears in the data table. For more information, see Specifying Material Data as a Function of Temperature and Independent Field Variables.
Number of field variables	Specify material parameters that depend on field variables. Field columns appear in the data table for each field variable you add. For more information, see Specifying Material Data as a Function of Temperature and Independent Field Variables.

Tension Hardening

Tension hardening data include the yield stress in uniaxial tension and the corresponding plastic strain.


Input Data	Description
Sigma T	Yield stress in uniaxial tension, $σ_{t}$ .
Epsilon T	Corresponding plastic strain. (The first tabular value entered must always be zero.)
Use temperature-dependent data	Specifies material parameters that depend on temperature. A Temperature field appears in the data table. For more information, see Specifying Material Data as a Function of Temperature and Independent Field Variables.
Number of field variables	Specify material parameters that depend on field variables. Field columns appear in the data table for each field variable you add. For more information, see Specifying Material Data as a Function of Temperature and Independent Field Variables.