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doc:user:elements:volumes:yield_stress [2016/02/02 17:59] – [CowperSymondsYieldStress] wauteletdoc:user:elements:volumes:yield_stress [2020/07/08 10:27] (current) – [SellarsTeggartYieldStress] papeleux
Line 298: Line 298:
 |$\Theta_{0}$  |   ''KM_THETA0''          ''TM/TO''        |  |$\Theta_{0}$  |   ''KM_THETA0''          ''TM/TO''        | 
 |${\dot{\bar{\varepsilon}}^{vp}_{0}}$ |   ''KM_DEVPL0''    |  ''-''           | |${\dot{\bar{\varepsilon}}^{vp}_{0}}$ |   ''KM_DEVPL0''    |  ''-''           |
 +
 +
 +===== SellarsTeggartYieldStress =====
 +
 +Yield Stress used for hot rolling defined by  :
 +  * a Static term : 
 +$$
 +S0 = \sqrt{3}  \; KK (\sqrt{3}  \;\bar{\varepsilon}^{vp})^{M0}
 +$$
 +  * a Dynamic Term : 
 +$$
 +Ss = As  \; asinh((\frac{\dot{\bar{\varepsilon}}^{vp}}{Zs})^{Ms})
 +$$
 +  * for the Yield Stress computed by : 
 +$$
 +\sigma_{yield}  = S0 + (Ss - S0) (1-e^{-C \; \bar{\varepsilon}^{vp}})^{R}
 +$$
 +
 +=== Parameters === 
 +
 +^          Name                            Metafor Code  ^ Dependency         ^
 +|$KK $                                      ''SELLARSTEGGART_KK'' |  ''TM/TO''         
 +|$M0 $                                      ''SELLARSTEGGART_M0'' |  ''TM/TO''         |
 +|$As $                                      ''SELLARSTEGGART_AS'' |  ''TM/TO''         |
 +|$Zs $                                      ''SELLARSTEGGART_MS'' |  ''TM/TO''         
 +|$Ms $                                      ''SELLARSTEGGART_ZS'' |  ''TM/TO''         |
 +|$C $                                      |  ''SELLARSTEGGART_R'' |  ''TM/TO''         |
 +|$R $                                      |  ''SELLARSTEGGART_C'' |  ''TM/TO''         |
 +
 +
 +===== PythonYieldStress =====
 +
 +User defined Yield Stress by a pythonDirector :
 +Python Director allows user to define their own Yield Stress law. Four functions has to be defined in the Python Class : a constructor (__init__), a destructor (__del__) that must never be called, and the computation functions : getYieldStress (returning YieldStress) and getYieldHardening (returning h).
 +See the example below of a Perzyna law : 
 +<code>
 +
 +class MyYieldStress(PythonYieldStress):
 +    def __init__(self, _no, _svm0, _h, _K, _m):
 +        print("MyYieldStress: __init__")
 +        PythonYieldStress.__init__(self,_no)
 +        self.svm0 = _svm0
 +        self.h    = _h
 +        self.K    = _K
 +        self.m    = _m        
 +    def __del__(self):
 +        print("MyIsoH : __del__")
 +        print("callToDestructor of MyYieldStress not allowed. Add MyIsoH.__disown__()")
 +        input('')
 +        exit(1)
 +    def getYieldStress(self, evpl, deltaEvpl, dTime, yieldGPState, pLaw):
 +        #print "MyYieldStress compute Yield Stress"
 +        if dTime > 0.0:
 +            dEvpl = deltaEvpl/dTime
 +        else:
 +            dEvpl = 0.0
 +        sigH = self.svm0+evpl*self.h
 +        sigV = self.K*pow(dEvpl, self.m)
 +        #yieldGPState.setVpStress(sigV)
 +        return sigH+sigV
 +    def getYieldHardening(self, epl, deltaEvpl, dTime, yieldGPState, pLaw) :
 +        if dTime > 0.0:
 +            dEvpl = deltaEvpl/dTime
 +            h = self.h + (self.K*pow(dEvpl, self.m-1))/dTime
 +        else:
 +            dEvpl = 0.0
 +            h = self.h
 +        return h
 +</code>
 +
doc/user/elements/volumes/yield_stress.1454432398.txt.gz · Last modified: 2016/03/30 15:22 (external edit)

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