Not really experienced with eigen so I am not exactly sure.
Abbas
On Tuesday, August 1, 2023 at 6:53:35 PM UTC+2 dim...@gmail.com wrote:
> 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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