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FRICTION.html
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<html><head><link rel="stylesheet" type="text/css" href="style.css"/></head><body> <H2> <BR> *FRICTION </H2> <P> Keyword type: model definition, surface interaction and step <P> With this option the friction behavior of a surface interaction can be defined. The friction behavior is optional for contact analyses. There are no parameters. <P> The frictional behavior defines the relationship between the shear stress in the contact area and the relative tangential displacement between the slave and the master surface. It is characterized by a linear range with tangent <SPAN CLASS="MATH"><B><IMG WIDTH="13" HEIGHT="15" ALIGN="BOTTOM" BORDER="0" SRC="img44.png" ALT="$ \lambda$"></B></SPAN> (stick slope) for small relative displacements (stick) followed by a horizontal upper bound (slip) given by <SPAN CLASS="MATH"><B><IMG WIDTH="21" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img2394.png" ALT="$ \mu p$"></B></SPAN>, where <SPAN CLASS="MATH"><B><IMG WIDTH="13" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img51.png" ALT="$ \mu$"></B></SPAN> is the friction coefficient and <SPAN CLASS="MATH"><B><IMG WIDTH="12" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img342.png" ALT="$ p$"></B></SPAN> the local pressure (Figure 131). <SPAN CLASS="MATH"><B><IMG WIDTH="13" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img51.png" ALT="$ \mu$"></B></SPAN> is dimensionless and usually takes values between 0.1 and 0.5, <SPAN CLASS="MATH"><B><IMG WIDTH="13" HEIGHT="15" ALIGN="BOTTOM" BORDER="0" SRC="img44.png" ALT="$ \lambda$"></B></SPAN> has the dimension of force per volume and should be chosen to be about 100 times smaller than the spring constant. If no value for <SPAN CLASS="MATH"><B><IMG WIDTH="13" HEIGHT="15" ALIGN="BOTTOM" BORDER="0" SRC="img44.png" ALT="$ \lambda$"></B></SPAN> is specified a default is taken equal to the first elastic constant of the first encountered material in the input deck divided by 2. <P> For face-to-face penalty contact with PRESSURE-OVERCLOSURE=TIED the value of the friction coefficient is irrelevant. <P> <P><P> <BR> <P> First line: <UL> <LI>*FRICTION </LI> </UL> <P> Following line for all types of analysis except modal dynamics: <UL> <LI><SPAN CLASS="MATH"><B><IMG WIDTH="50" HEIGHT="31" ALIGN="MIDDLE" BORDER="0" SRC="img2395.png" ALT="$ \mu (>0)$"></B></SPAN>. </LI> <LI><!-- MATH $\lambda (>0)$ --> <SPAN CLASS="MATH"><B><IMG WIDTH="50" HEIGHT="31" ALIGN="MIDDLE" BORDER="0" SRC="img2396.png" ALT="$ \lambda (>0)$"></B></SPAN>. </LI> </UL> <P> <PRE>
Example:
*FRICTION
0.2,5000.
</PRE> <P> defines a friction coefficient of 0.2 and a stick slope of 5000. <P> <P><P> <BR> Example files: friction1, friction2. <P> </body></html>