Line data    Source code

       1             : //* This file is part of the MOOSE framework
       2             : //* https://mooseframework.inl.gov
       3             : //*
       4             : //* All rights reserved, see COPYRIGHT for full restrictions
       5             : //* https://github.com/idaholab/moose/blob/master/COPYRIGHT
       6             : //*
       7             : //* Licensed under LGPL 2.1, please see LICENSE for details
       8             : //* https://www.gnu.org/licenses/lgpl-2.1.html
       9             : 
      10             : #include "ExplicitMassDamping.h"
      11             : #include "MooseError.h"
      12             : #include "FEProblemBase.h"
      13             : #include "NonlinearSystemBase.h"
      14             : 
      15             : registerMooseObject("SolidMechanicsApp", ExplicitMassDamping);
      16             : 
      17             : InputParameters
      18          18 : ExplicitMassDamping::validParams()
      19             : {
      20          18 :   InputParameters params = NodalKernel::validParams();
      21          18 :   params.addClassDescription(
      22             :       "Adds Rayleigh mass damping, eta * M * v, to an ExplicitMixedOrder solid mechanics model.");
      23          54 :   params.addRangeCheckedParam<Real>(
      24             :       "eta",
      25          36 :       0.0,
      26             :       "eta >= 0.0",
      27             :       "Damping strength.  Mass damping helps to damp low-frequency, large-scale oscillations.  A "
      28             :       "reasonable value to use initially is eta = 2 * d * omega, where d is the damping fraction "
      29             :       "(typically 0.1) and omega is the lowest relevant frequency mode of the model.  For "
      30             :       "instance, if the model is can oscillate longitudinally, omega = (pi / model_length) * "
      31             :       "sqrt(youngs_modulus / density)");
      32          18 :   return params;
      33           0 : }
      34             : 
      35           9 : ExplicitMassDamping::ExplicitMassDamping(const InputParameters & parameters)
      36             :   : NodalKernel(parameters),
      37           9 :     _eta(getParam<Real>("eta")),
      38           9 :     _mass_matrix_lumped(initLumpedMass()),
      39          18 :     _u_dot_old(_var.nodalValueDotOld())
      40             : {
      41           9 : }
      42             : 
      43             : Real
      44          96 : ExplicitMassDamping::computeQpResidual()
      45             : {
      46          96 :   const auto dofnum = _variable->nodalDofIndex(); // dof for current var
      47          96 :   return _eta * _mass_matrix_lumped(dofnum) * _u_dot_old;
      48             : }
      49             : 
      50             : const NumericVector<Number> &
      51           9 : ExplicitMassDamping::initLumpedMass()
      52             : {
      53           9 :   const auto & nl = _fe_problem.getNonlinearSystemBase(_sys.number());
      54          18 :   if (nl.hasVector("mass_matrix_lumped"))
      55          18 :     return nl.getVector("mass_matrix_lumped");
      56             : 
      57           0 :   mooseError("Lumped mass matrix is missing. Make sure ExplicitMixedOrder is being used as the "
      58             :              "time integrator.");
      59             : }