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CREEP.html
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<html><head><link rel="stylesheet" type="text/css" href="style.css"/></head><body> <H2> <BR> *CREEP </H2> <P> Keyword type: model definition, material <P> This option is used to define the creep properties of a viscoplastic material. There is one optional parameter LAW. Default is LAW=NORTON, the only other value is LAW=USER for a user-defined creep law. The Norton law satisfies: <P> <P></P> <DIV ALIGN="CENTER" CLASS="mathdisplay"><!-- MATH \begin{equation} \dot{\epsilon} = A \sigma^n t^m \end{equation} --> <TABLE CLASS="equation" CELLPADDING="0" WIDTH="100%" ALIGN="CENTER"> <TR VALIGN="MIDDLE"> <TD NOWRAP ALIGN="CENTER"><SPAN CLASS="MATH"><IMG WIDTH="79" HEIGHT="30" ALIGN="MIDDLE" BORDER="0" SRC="img2304.png" ALT="$\displaystyle \dot{\epsilon} = A \sigma^n t^m$"></SPAN></TD> <TD NOWRAP CLASS="eqno" WIDTH="10" ALIGN="RIGHT"> (<SPAN CLASS="arabic">696</SPAN>)</TD></TR> </TABLE></DIV> <BR CLEAR="ALL"><P></P> <P> where <SPAN CLASS="MATH"><B><IMG WIDTH="10" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" SRC="img247.png" ALT="$ \epsilon$"></B></SPAN> is the equivalent creep strain, <SPAN CLASS="MATH"><B><IMG WIDTH="13" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" SRC="img1293.png" ALT="$ \sigma$"></B></SPAN> is the true Von Mises stress an t is the total time. For LAW=USER the creep law must be defined in user subroutine creep.f (cf. Section 8.1). <P> All constants may be temperature dependent. The card should be preceded by a *ELASTIC card within the same material definition, defining the elastic properties of the material. If for LAW=NORTON the temperature data points under the *CREEP card are not the same as those under the *ELASTIC card, the creep data are interpolated at the *ELASTIC temperature data points. If a *PLASTIC card is defined within the same material definition, it should be placed after the *ELASTIC and before the *CREEP card. If no *PLASTIC card is found, a zero yield surface without any hardening is assumed. <P> If the elastic data is isotropic, the large strain viscoplastic theory treated in [84] and [85] is applied. If the elastic data is orthotropic, the infinitesimal strain model discussed in Section 6.8.13 is used. If a *PLASTIC card is used for an orthotropic material, the LAW=USER option is not available. <P><P> <BR> <P> First line: <UL> <LI>*CREEP </LI> <LI>Enter the LAW parameter and its value, if needed </LI> </UL> <P> Following lines are only needed for LAW=NORTON (default): First line: <UL> <LI>A. </LI> <LI>n. </LI> <LI>m. </LI> <LI>Temperature. </LI> </UL> Use as many lines as needed to define the complete temperature dependence. <P> <PRE>
Example:
*CREEP
1.E-10,5.,0.,100.
2.E-10,5.,0.,200.
</PRE> <P> defines a creep law with A=<SPAN CLASS="MATH"><B><IMG WIDTH="43" HEIGHT="18" ALIGN="BOTTOM" BORDER="0" SRC="img924.png" ALT="$ 10^{-10}$"></B></SPAN>, n=5 and m=0 for T(temperature)=100. and A=<!-- MATH $2 \cdot 10^{-10}$ --> <SPAN CLASS="MATH"><B><IMG WIDTH="63" HEIGHT="18" ALIGN="BOTTOM" BORDER="0" SRC="img2305.png" ALT="$ 2 \cdot 10^{-10}$"></B></SPAN> and n=5 for T(temperature)=200. <P> <P><P> <BR> Example files: beamcr. <P> </body></html>