Dashpot definition
- @DASHPOT_DEFINITION {
- @DASHPOT_NAME {DashpotName} {
- @FUNCTION_1D_TYPE {Fun1DType}
- @FUNCTION_1D_NAME {Fun1DName}
- @FUNCTION_1D_NAME {Fun1DNameDeriv}
- @COMMENTS {CommentText}
- }
- }
Introduction
A dashpot defines the nonlinear relationship between the viscous force and stretch rate of a viscous dashpot. Two types of dashpots can be defined.
- Rectilinear dashpots define the relationship between the dashpot viscous force, F^{vi}, and stretch rate, v. Rectilinear dashpots are used with relative displacement elements or are part of a more complex elastomeric device model.
- Torsional dashpots define the relationship between the dashpot viscous moment, M^{vi}, and twist rate, ω. Torsional dashpots are used with relative rotation elements or are part of a more complex elastomeric device model.
NOTES
- Parameter Fun1DType defines the nature of the dashpot. It can take either of two values.
- Fun1DType = RECTILINEAR_DASHPOT defines a rectilinear dashpot, and
- Fun1DType = TORSIONAL_DASHPOT defines a torsional dashpot.
- The characteristics of the dashpot are defined by 1D function, Fun1DName, F = F(x), which maps to F^{vi} = F^{vi}(v) and M^{vi} = M^{vi}(ω) for the rectilinear and torsional dashpots, respectively. The 1D function can be a Chebyshev function, a harmonic function, a tabulated function, or a user function. For tabulated functions, the discrete function must approximated by its expansion in terms of Chebyshev polynomials.
- It will also be required to compute the derivative of the dashpot force or moment with respect to the velocity or angular velocity, respectively. If the 1D function is defined as a Chebyshev, harmonic, or tabulated function, this derivative is computed analytically and a 1D function associated with this derivative will be generated automatically. If the 1D function is defined as a user function, this derivative must be provided as an independent user function, Fun1DNameDeriv. In this case, both Fun1DName and Fun1DNameDeriv must refer to user functions.
- It is possible to attach comments to the definition of the object; these comments have no effect on its definition.