General Mechanical

General Mechanical

Is the friction coefficient for a frictional contact the static or kinetic coefficient of friction?

    • rudilien
      Subscriber

      I am using static structural analysis to model the motion of a fault. I have the fault plane set up as a frictional contact so that I can specify the coefficient of friction. However, I do not know if the "friction coefficient" that I enter in is being used as a static or kinetic coefficient of friction. I would like the model to be set up so that the maximum static frictional force needs to be exceeded before the plane can slide. I've attached in image showing what the geometry looks like: the frictional contact is along the angled contact between the orange and green blocks. The horizontal contact at the base of the orange block is bonded.

    • 1shan
      Ansys Employee
      Coulomb friction model is the default model for a frictional contact. In the model two contacting surfaces can carry shear stresses up to a certain magnitude across their interface before they start sliding relative to each other. This state is known as sticking. The Coulomb friction model defines an equivalent shear stress¤ä, at which sliding on the surface begins as a fraction of the contact pressure p (¤ä =┬Áp + COHE, where┬Á is the friction coefficient and COHE specifies the cohesion sliding resistance). Once the shear stress is exceeded, the two surfaces will slide relative to each other. This state is known as sliding. This is same as what you are expecting. If you want to specify a different static and dynamic coefficient of friction have a look at 3.9.5.4. Static and Dynamic Friction Coefficients
      Regards Ishan.
    • rudilien
      Subscriber
      Thanks for your reply, Ishan.
      This clears up my initial question, but how does Ansys calculate/define the magnitude of maximum shear stress before sliding starts? Is this based off of the material properties? Is the COHE value also determined from material properties? I have been specifying density, temperature, and isotropic linear elastic material properties (Poisson's ratio, Young's mod., bulk mod., shear mod.) in my models.
    • rudilien
      Subscriber
      Please see my above comment - I forgot to tag you when I posted it.
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