From 898b8bbb014de5da71738db347c0858abc02e432 Mon Sep 17 00:00:00 2001
From: Wenqing Wang <wenqing.wang@ufz.de>
Date: Mon, 30 Jul 2018 10:44:47 +0200
Subject: [PATCH] [BGRa] Added some comments
---
MaterialLib/SolidModels/CreepBGRa.cpp | 20 +++++++++++++++-----
MaterialLib/SolidModels/CreepBGRa.h | 2 +-
2 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/MaterialLib/SolidModels/CreepBGRa.cpp b/MaterialLib/SolidModels/CreepBGRa.cpp
index 8cf369dc4a6..5448fcf4355 100644
--- a/MaterialLib/SolidModels/CreepBGRa.cpp
+++ b/MaterialLib/SolidModels/CreepBGRa.cpp
@@ -48,19 +48,29 @@ CreepBGRa<DisplacementDim>::integrateStress(
std::exp(-_q / (MaterialLib::PhysicalConstant::IdealGasConstant * T));
auto const& deviatoric_matrix = Invariants::deviatoric_projection;
+ // In newton_solver.solve(), the Jacobian is calculated first, and then
+ // then comes the assembly of the residue vector. In order to save
+ // computation time, the following two variables are set visible in this
+ // function. The two variables keep the computation results of the
+ // norm of the deviatoric stress and 2bG||s_{n+1}||^{n-1} in
+ // update_jacobian, and then they are directly used in update_residual
+ // without repeating the computation. Of course, update_jacobian is not a
+ // pure function anymore, but has side effects.
double pow_norm_s_n1_n_minus_one_2b_G = 0.;
KelvinVector s_n1;
auto const update_jacobian = [&](JacobianMatrix& jacobian) {
+ // side effect
s_n1 = deviatoric_matrix * solution;
double const norm_s_n1 = Invariants::FrobeniusNorm(s_n1);
+ // side effect
pow_norm_s_n1_n_minus_one_2b_G =
2.0 * b * this->_mp.mu(t, x) * std::pow(norm_s_n1, _n - 1);
- jacobian =
- KelvinMatrix::Identity() +
- pow_norm_s_n1_n_minus_one_2b_G *
- (deviatoric_matrix + ((_n - 1) / (norm_s_n1 * norm_s_n1)) *
- s_n1 * s_n1.transpose());
+ jacobian = KelvinMatrix::Identity() +
+ pow_norm_s_n1_n_minus_one_2b_G *
+ (deviatoric_matrix +
+ ((_n - 1) / (norm_s_n1 * norm_s_n1)) * s_n1 *
+ s_n1.transpose());
};
auto const update_residual = [&](ResidualVectorType& r) {
diff --git a/MaterialLib/SolidModels/CreepBGRa.h b/MaterialLib/SolidModels/CreepBGRa.h
index 84c7afdeb95..77549fdde0c 100644
--- a/MaterialLib/SolidModels/CreepBGRa.h
+++ b/MaterialLib/SolidModels/CreepBGRa.h
@@ -93,7 +93,7 @@ public:
private:
NumLib::NewtonRaphsonSolverParameters const _nonlinear_solver_parameters;
- const double _n; /// parameter determined by experiments.
+ const double _n; /// Creep rate exponent n.
/// $fA\left(\frac{3}{2}\right)^{n/2+1}/\sigma_{eff}^n $f
const double _coef;
const double _q; /// Activation energy
--
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