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Free (the default) to leave the displacement component unconstrained
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Prescribed to constrain the displacement component to a given value. Enter a scalar value for the component of the prescribed displacement u0.
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Limited to set a maximum and a minimum limit for the displacement component. Enter a scalar value for the component of the maximum displacement u0,max and the minimum displacement u0,min. By default, they are set to Inf and -Inf, which corresponds to no active constraint.
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The default value for the Penalty factor kp depends on what type of entity the Prescribed Displacement/Rotation node is added to.
In these expressions, beam is the tag of the Beam interface and <tag> is the tag of the Prescribed Displacement/Rotation node. The expressions are given as an estimation to the bending stiffness of the beam, where beam.Eequ is the equivalent Young’s modulus, beam.re is the equivalent radius of gyration, and beam.area is the cross-section area. The variable beam.<tag>.charLen is by default equal to the length of the mesh element. To improve the estimate of the penalty factor, replace beam.<tag>.charLen with the free length of the beam. The penalty factor can also be tuned by changing the multiplier at the beginning of each expression.
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For 2D models, to define a prescribed rotation select the Prescribed in out of plane direction check box and enter a value or expression for θ0z.
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In the COMSOL Multiphysics Reference Manual:
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