Hello Everyone,
Thanks for your response.
The problem is how to calculate the average strain and stress values using
Area Average Method (for the geometry attached in previous mail)?
I am using this formula *Avg Strain = (A1E1+A2E2.....AnEn/A)* for the
calculation. I have calculated the values of E1,E2.. En using
DataPostProcedure Class but now the problem is how to calculate A1,A2....An
in the same class as active.cell_iterator showing the error?
*What I have done so far:*
*1. I have calculated strain and stress using DataPostProcedure Class*
template <int dim>
class StrainPostprocessor : public DataPostprocessorTensor<dim>
{
public:
StrainPostprocessor ()
:
DataPostprocessorTensor<dim> ("strain",
update_gradients)
{}
virtual
void
evaluate_vector_field
(const DataPostprocessorInputs::Vector<dim> &input_data,
std::vector<Vector<double> > &computed_quantities) const override
{
AssertDimension (input_data.solution_gradients.size(),
computed_quantities.size());
for (unsigned int p=0; p<input_data.solution_gradients.size(); ++p)
{
AssertDimension (computed_quantities[p].size(),
(Tensor<2,dim>::n_independent_components));
for (unsigned int d=0; d<dim; ++d)
for (unsigned int e=0; e<dim; ++e)
computed_quantities[p][Tensor<2,dim>::component_to_unrolled_index(TableIndices<2>(d,e))]
= (input_data.solution_gradients[p][d][e]
+
input_data.solution_gradients[p][e][d]) / 2;
}
}
};
*2. I have calculated area of each cell using active.cell_iterator
separately *
Triangulation<2> triangulation;
std::vector<double> x(4);
std::vector<double> y(4);
std::vector<double> A(4);
GridGenerator::hyper_cube(triangulation,-1,1);
//double A;
// double B;
// double C;
triangulation.refine_global(1);
int j =0;
for (const auto &cell : triangulation.active_cell_iterators())
{
int i =0;
for (const auto v : cell->vertex_indices())
{
x[i] = cell->vertex(v)(0);
y[i] = cell->vertex(v)(1);
std::cout<< "cord_x" << x[i]<<std::endl;
std::cout<< "cord_y" << y[i]<<std::endl;
i = i+1 ;
}
A[j] = (1./2.)*((x[0]*y[1] + x[1]*y[3] + x[3]*y[2] +
x[2]*y[0]) - (x[1]*y[0] + x[3]*y[1] + x[2]*y[3] + x[0]*y[2]));
std::cout<<"area"<<""<< A[j] <<std::endl;
j=j+1;
}
*what I want to do:*
Now I want to calculate both strain/stress and area in a single go so that
we can get the product of these two.
Kindly suggest if there is any other method to calculate avg strain/stress
using composite material where the size of elements in matrix and inclusion
are different.
Thanks,
Deepika
On Thu, Mar 2, 2023 at 7:39 PM Abbas <abbas.ballou...@gmail.com> wrote:
> Daniel,
>
> Side question:
> If I have to output gradients of a variable, the straightforward approach
> would be to evaluate the gradients over quadrature points and then average.
> This gives me an average value of my gradient per cell.
> Do you know how does data DataPostProcessor evaluates the value of the
> gradient at the mesh nodes? How does it it work under the hood? Do you mind
> explaining?
>
> Deepika,
>
> This is a strain post processor. Create a function that does this:
> template <int dim>
> class StrainPostprocessor : public DataPostprocessorTensor<dim>
> {
> public:
> StrainPostprocessor()
> : DataPostprocessorTensor<dim>("strain",
> update_gradients)
> {
> }
>
> virtual void evaluate_vector_field(const DataPostprocessorInputs::Vector<
> dim> &input_data, std::vector<Vector<double>> &computed_quantities) const
> override
> {
> AssertDimension(input_data.solution_gradients.size(),
> computed_quantities.size());
>
> for (unsigned int p = 0; p < input_data.solution_gradients.size(); ++p)
> {
> AssertDimension(computed_quantities[p].size(),
> (Tensor<2, dim>::n_independent_components));
>
> for (unsigned int d = 0; d < dim; ++d)
> for (unsigned int e = 0; e < dim; ++e)
> computed_quantities[p][Tensor<2, dim>::component_to_unrolled_index(
> TableIndices<2>(d, e))] = (input_data.solution_gradients[p][d][e] +
> input_data.solution_gradients[p][e][d]) /
> 2;
> }
> }
> };
>
> Then in data output you can do this:
> void CG_Elasticity_Linear<dim>::output_results(unsigned int
> refinement_level, unsigned int cycle) const
> {
>
> std::vector<DataComponentInterpretation::DataComponentInterpretation>
> interpretation(dim,
> DataComponentInterpretation::component_is_part_of_vector);
> std::vector<std::string> solution_names(dim, "u");
>
> DataOut<dim> data_out;
>
> data_out.add_data_vector(dof_handler, solution, solution_names,
> interpretation);
> const StrainPostprocessor<dim> strain;
> data_out.add_data_vector(dof_handler, solution, strain);
> data_out.build_patches();
>
> std::ofstream output("solution" + std::to_string(refinement_level) + "_" +
> std::to_string(cycle) + ".vtu");
>
> data_out.write_vtu(output);
>
> }
> For averages you'll have to loop in the DataPostProcessor derived class
> and average your quantity.
>
>
> Best,
> Abbas
>
> On Thursday, March 2, 2023 at 12:42:46 PM UTC+1 d.arnd...@gmail.com wrote:
>
>> Deepika,
>>
>> > How can I calculate the average stress and strain values for the
>> following geometry (Where element size is not uniform) using the Data
>> PostProcedure?
>>
>> Can you describe what you are trying to do in a formula?
>> DataPostProcessor typically gives you a result per grid point in the output
>> step.
>>
>> > 2. Is it possible to make a uniform mesh so the size of elements in
>> both (inclusion and matrix) will be the same?
>>
>> If you can draw a mesh that you would like to use, you should also be
>> able to create that in deal.II to use. Of course, it will be very difficult
>> to achieve the same size for all elements since you will need more cells to
>> describe the inclusions anyway.
>>
>> Best,
>> Daniel
>>
>> On Wed, Mar 1, 2023 at 6:38 PM Deepika Kushwah <deepika...@iitgoa.ac.in>
>> wrote:
>>
>>> Hello Everyone,
>>>
>>> I have the following queries :
>>> 1. How can I calculate the average stress and strain values for the
>>> following geometry (Where element size is not uniform) using the Data
>>> PostProcedure?
>>>
>>> [image: image.png]
>>> 2. Is it possible to make a uniform mesh so the size of elements in both
>>> (inclusion and matrix) will be the same?
>>>
>>> Thanks & Regards
>>> Deepika
>>>
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