Hello Abbas,
Thanks for your reply.
I will take a look at the step13.
Howerver, I would like to know if the cell matrix transform seems like the
process below:
const Eigen::MatrixXd& cell_matrix,
const Eigen::VectorXd& cell_youngs_modulus,
const std::vector<int>& local_dof_indices,
Eigen::MatrixXd& tangent_matrix,
Eigen::VectorXd& global_youngs_modulus)
const int N = cell_matrix.rows();
const int M = tangent_matrix.rows();
// Loop over the local degrees of freedom
for (int i = 0; i < N; ++i) {
const int global_i = local_dof_indices[i]; // Global index of the
i-th local dof
// Add the contribution of the i-th local dof to the global Young's
modulus vector
global_youngs_modulus(global_i) += cell_youngs_modulus(i);
for (int j = 0; j < N; ++j) {
const int global_j = local_dof_indices[j]; // Global index of
the j-th local dof
// Add the contribution of the (i,j)-th entry of the cell
matrix multiplied by the i-th and j-th Young's modulus to the global
tangent matrix
tangent_matrix(global_i, global_j) += cell_matrix(i, j) *
cell_youngs_modulus(i) * cell_youngs_modulus(j);
}
}
I am not quite sure if the assembly process for the global stiffness matrix
is correct.
Best regards
Lance
On Tuesday, August 1, 2023 at 11:47:12 AM UTC+2 abbas.b...@gmail.com wrote:
> Lance,
>
> I am not sure if I understood you correctly.
> Maybe looking at the local_assemble_matrix() function in step:13 might
> help.
>
> Abbas
>
> On Tuesday, August 1, 2023 at 11:00:10 AM UTC+2 dim...@gmail.com wrote:
>
>> Hello dear group,
>>
>> I have one question which is about how to build global stiffness matrix
>> with cell stiffness matrix.
>>
>> In our project,the density is a vector (actually we need a mu vector but
>> in the code of deallii mu is a scalar)with different values,I would like to
>> use the element of density vector to build cell matrix as written in the
>> link below:
>>
>>
>> https://www.dealii.org/current/doxygen/code-gallery/Quasi_static_Finite_strain_Compressible_Elasticity/cook_membrane.cc
>> (starting from line 1782)
>>
>> And finally the cell stiffness matrix is used to build global stiffness
>> matrix,but I don' know how the global stiffness matrix is bulit with cell
>> stiffness matrix.
>>
>>
>> https://www.dealii.org/current/doxygen/code-gallery/Quasi_static_Finite_strain_Compressible_Elasticity/cook_membrane.cc
>> (starting from line 1599)
>> //>>>>>>>>>>>>>>>>>>>>>>>>>>
>> constraints.distribute_local_to_global(
>> data.cell_matrix,
>> data.cell_rhs,
>> data.local_dof_indices,
>> tangent_matrix,
>> system_rhs);
>> }
>>
>>
>> //<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>
>>
>> I have a idea that I use mu[0] to obtain the first cell_matrix and use
>> mu[1] to get the second cell stiffness matrix ,step by step then I got
>> final mu[m] to obtain the last cell stiffness matrix and in the end I use
>> some function like distribute_local_to_global to construct the global
>> stiffness matrix,and system rhs and even the solutions.
>>
>> I checked the code in
>> AffineConstraints<number>::distribute_local_to_global
>> <https://www.dealii.org/current/doxygen/deal.II/classAffineConstraints.html#a373fbdacd8c486e675b8d2bff8943192>.
>>
>> (
>> https://www.dealii.org/current/doxygen/deal.II/affine__constraints_8h_source.html
>> )
>> But the hint information guides me to read the cm.templates.h file.
>> ewcfp I was a little confused ,I did not find the file from dealii lib.
>> could anyone provide any information or hint? Thanks in advance!
>> Best regards
>> Lance
>> Could
>>
>> I
>>
>
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