Hardening Laws

Plasticity materials implement their yield behavior by combining them with hardening laws. The material definition sets the equation of state properties for the material and the selected hardening law determines the yield criterion.

Selecting a Hardening Law

Hardening laws are assigned to materials within their material definition. When using NairnFEAMPM or NairnFEAMPMViz, a hardening law is added within a material command block as follows:

Material ID,name,type
      .
   plasticLaw (Law_Name or number)
   Law_Property (value)
      .
      .
Done

Selecting a hardening law in a XML input file has the form:

<Material Type='#' Name='name'>
        .
     <plasticLaw>(Law_Name or number)</plasticLaw>
     <Law_property>(value)</Law_property>
        .
</Material>

In both these options:

• plasticLaw is the name or number of the desired hardening law (see table of available hardening laws).
• Law_Property - after selecting the hardening law, set all required properties for that law. Refer to each hardening law for the names and descriptions of properties that can be set. The (value) is the value for that property.

Available Hardening Laws

Materials that allow hardening laws can pick them from the following table. Unless otherwise stated, any such material can use any hardening law. By mixing and matching materials and hardening laws you have options for many types of materials. A single material definition, however, can only use one hardening law.

Name	Number	Description
Linear	1	Linear hardening (which includes elastic-plastic as a special case)
Nonlinear	2	Nonlinear hardening law
Nonlinear2	6	An alternate nonlinear hardening law
JohnsonCook	3	Johnson Cook hardening law
SCGL	4	Steinberg-Cochran-Guinan hardening law
SL	5	Steinberg-Lund hardening law