View source for Isotropic Plastic Softening Material

== Constitutive Law ==

This [[Material Models|MPM Material]] is an isotropic, elastic-plastic material that can also develop aniostropic damage. The material is available only in [[OSParticulas]].

In the absense of damage, this material is identical to an [[Isotropic, Elastic-Plastic Material]]. In the absence of plasticity, this material is identical to an [[Isotropic Softening Material]]. If conditions allow, the material can develop both plasticity and damage with softening. Note that if plastic yield properties are below damage initiation stress, the material may have never reach stress to cause damage. But, if the plastic properties allow hardening, the material can yield first and then start damage after hardening allows stresses to reach stress for initiation of damage.

== Material Properties ==

For material properties, combine all options available for an [[Isotropic, Elastic-Plastic Material]] and for an [[Isotropic Softening Material]]. This material must, however, use large rotation mode (as is also required for an [[Isotropic Softening Material]]).

{| class="wikitable"
|-
! Property !! Description !! Units !! Default
|-
| ([[Isotropic Material#Material Properties|Isotropic Properties]]) || Enter all properties needed to define the underlying isotropic material response || varies || varies
|-
| ([[Isotropic, Elastic-Plastic Material#Material Properties|Isotropic, Plastic Properties]]) || Enter yield properties and a [[Hardening Laws|hardening law]], but cannot use a [[Hardening Laws|hardening law]] that changes shear modulus ([[Steinberg-Cochran-Guinan Hardening]] or [[Steinberg-Lund Hardening]]) || varies || varies
|-
| ([[Isotropic Softening Material#Material Properties|Isotropic Softening Properties]]) || Enter properties for initiation of damage and for two softening laws  || varies || varies
|-
| ([[Common Material Properties|other]]) || Properties common to all materials and must use the large rotation option || varies || varies
|}

== History Variables ==

The chosen [[Hardening Laws|hardening law]] will have at least one history variable and will start with history variable number 1. After the  [[Hardening Laws|hardening law]] history variables, the remaining variables will be for the [[Isotropic Softening Material]] material. The softening history variable will be offset by the number of  [[Hardening Laws|hardening law]] history variables. Because plastic strain tracks sum of plastic and cracking strain, three additional history variables (compared to  [[Isotropic Softening Material]]) track the three components of cracking strains in the crack axis system corresponding to normal and shear crack opening displacements.

Let P and S be number of history variable for the plastic law in use and for [[Isotropic Softening Material]] history variables, respectively. The history variable for this material are then:

* 1 to P: Plastic law history variables
* P+1 to P+S: [[Isotropic Softening Material]] history variables
* P+S+1: ε<sub>c,xx</sub> or x direction cracking strain normal to crack in the crack axis system
* P+S+2: <sub>c,xy</sub> or x-y direction shear cracking strain in the crack axis system
* P+S+3: γ<sub>c,xz</sub> or x-z direction shear cracking strain in the crack axis system

This material also tracks sum of plastic strain and cracking strain which can be saved by using the [[MPM Archiving Options|<tt>plasticstrain</tt> archiving option]]. The total plastic plus cracking strain is archived in the global axis system.

If you also [[MPM Archiving Options|archive the <tt>damagenormal</tt>]], you will be able to plot a vector along the crack-opening displacement vector.

== Examples ==

 Material "isoplastsoft","Isotropic Plastic Softening Material",53
   E 1000
   nu .33
   a 60
   rho 1
   largeRotation 1
   Initiation MaxPrinciple
   sigmac 30
   tauc 20
   SofteningI Linear
   I-Gc 10000
   SofteningII Linear
   II-Gc 10000
   Hardening Linear
   yield 20
   Ep 200
 Done