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 "DensityScaling.h"
      11             : #include "libmesh/utility.h"
      12             : 
      13             : registerMooseObject("SolidMechanicsApp", DensityScaling);
      14             : 
      15             : InputParameters
      16          28 : DensityScaling::validParams()
      17             : {
      18          28 :   InputParameters params = Material::validParams();
      19          28 :   params.addClassDescription(
      20             :       "Computes the scaled inertial density needed to enable stable explicit time-stepping using "
      21             :       "the "
      22             :       "desired_time_step in solid-mechanics problems.  Note that if this inertial density is used "
      23             :       "in input files (for instance, in the mass matrix) it will impact the dynamics of the "
      24             :       "system, largely eliminating high-frequency oscillations, and impacting low-frequency "
      25             :       "dynamics.  Hence, use with caution.");
      26          56 :   params.addRequiredParam<MaterialPropertyName>(
      27             :       "true_density",
      28             :       "Name of Material Property defining the true inertial density of the material.");
      29          56 :   params.addRequiredParam<MaterialPropertyName>(
      30             :       "scaled_density", "Name of the scaled density property that this Material computes.");
      31          56 :   params.addParam<MaterialPropertyName>(
      32             :       "additional_density",
      33             :       "additional_density",
      34             :       "Name of the additional density property that this Material computes");
      35          56 :   params.addRequiredParam<Real>("desired_time_step", "The desired time step.");
      36          84 :   params.addRangeCheckedParam<Real>(
      37             :       "safety_factor",
      38          56 :       0.7,
      39             :       "(safety_factor>0) & (safety_factor<=1)",
      40             :       "The scaled density that this Material produces will potentially allow stable time-step "
      41             :       "sizes of desired_time_step / safety_factor.  In practice, however, using such a time step "
      42             :       "might result in instabilities, because of time-step lagging and the approximate critical "
      43             :       "time-step formula used by this Material.  Hence, safety_factor allows for a safety margin.");
      44          28 :   return params;
      45           0 : }
      46             : 
      47          21 : DensityScaling::DensityScaling(const InputParameters & parameters)
      48             :   : Material(parameters),
      49          21 :     _desired_time_step(getParam<Real>("desired_time_step")),
      50          42 :     _density_scaled(declareProperty<Real>(getParam<MaterialPropertyName>("scaled_density"))),
      51          21 :     _additional_density(
      52          42 :         declareProperty<Real>(getParam<MaterialPropertyName>("additional_density"))),
      53          42 :     _material_density(getMaterialProperty<Real>("true_density")),
      54          42 :     _sqrt_effective_stiffness(getMaterialPropertyByName<Real>("effective_stiffness")),
      55          63 :     _safety_factor(getParam<Real>("safety_factor"))
      56             : {
      57          21 : }
      58             : 
      59             : void
      60        1264 : DensityScaling::computeQpProperties()
      61             : {
      62        1264 :   const Real stable_density = Utility::pow<2>(_sqrt_effective_stiffness[_qp] * _desired_time_step /
      63        1264 :                                               _safety_factor / _current_elem->hmin());
      64             : 
      65        1264 :   _density_scaled[_qp] = std::max(stable_density, _material_density[_qp]);
      66        1264 :   _additional_density[_qp] = _density_scaled[_qp] - _material_density[_qp];
      67        1264 : }