[Paraview] calculator tensor field

[Marschmann at stud.uni-heidelberg.de]

Dear Utkarsh,

I changed the Result Array names to sigmaXX etc but still get the same  
error message.
I think the problem is with the product between the two unit vectors.
Simply calculating for example " iHat*iHat " yields the same error message.

Would you know in general how to form a tensor field in paraview from  
its components?

Thanks,
Gianna









Quoting Utkarsh Ayachit <utkarsh.ayachit at kitware.com>:

> Gianna,
>
> For Calculator filter,  names with "_X", "_Y" have special meaning.
> Try change Calulators 1-9 to use Result Array names as "sigmaXX",
> "sigmaYY", etc.
> Does that work?
>
> Utkarsh
>
> On Mon, Oct 6, 2014 at 6:31 PM,  <Marschmann at stud.uni-heidelberg.de> wrote:
>> Hello Utkarsh,
>> thanks for looking at it.
>> Attached is the state file:
>> - Calculators 1-6 calculate the 6 independent components of the symmetric
>> stress tensor sigma_ij
>>
>> - Calculators 7-9 calculate the traction vectors s_i from the stress
>> components (s_i = sigma_ij e_j , summation over j implied, e_j basis
>> vectors)
>>
>> Now in another calculator I'd like to compute the stress tensor field,
>> either directly from the stress components sigma_ij or from the traction
>> vectors. Both approaches fail with the error message.
>> The stress tensor is given by
>> sigma =
>> sigma_xx(e_x*e_x)+sigma_yy(e_y*e_y)+sigma_zz(e_z*_ez)+sigma_xy)(e_xe_y+e_ye_x)+sigma_xz(e_xe_z+e_ze_x)+sigma_yz(e_ye_z+e_ze_y)
>> equivalent to
>> sigma = s_x*e_x + s_y*e_y +s_z*e_z
>>
>> Thanks,
>> Gianna
>>
>>
>>
>> Quoting Utkarsh Ayachit <utkarsh.ayachit at kitware.com>:
>>
>>> Can you attach a sample data file/state file? That'll make it easier
>>> to identify the problem and suggest a solution.
>>>
>>> Thanks
>>> Utkarsh
>>>
>>> On Sat, Oct 4, 2014 at 4:14 AM,  <Marschmann at stud.uni-heidelberg.de>
>>> wrote:
>>>>
>>>> Hello everyone,
>>>>
>>>> I have three displacement field vector components u, v, w in my .vtk file
>>>> and wish to display the associated stress tensor.
>>>> I made the following steps:
>>>>
>>>> - Apply the filter Gradient Of Unstructued DataSet
>>>> -> Now have 9 scalars Gradient_0, ... , Gradient 8
>>>>
>>>> - compute components of stress tensor via sigma_ij = div(Gradient) +
>>>> u_i,j
>>>> -> Now have additional 9 scalars sigma_ij
>>>>
>>>> - from this form traction vectors:
>>>> T_i = sigma_ij e_j   ,where e_j are the unit vectors iHat
>>>>
>>>> -> Now have three traction vectors from which the tensor field
>>>> computation
>>>> doesnt work:
>>>>
>>>> - I do Result = T_1*iHat + T_2*jHat + T_3*kHat for the tensor calculation
>>>> and get the following error message:
>>>>
>>>> ERROR: In
>>>>
>>>> /home/abuild/rpmbuild/BUILD/ParaView-v4.0.1-source/VTK/Common/Misc/vtkFunctionParser.cxx,
>>>> line 201
>>>> vtkFunctionParser (0x205ddac0): Parse: Error deciding between ambiguous
>>>> operators
>>>>
>>>>
>>>> ERROR: In
>>>>
>>>> /home/abuild/rpmbuild/BUILD/ParaView-v4.0.1-source/VTK/Common/Misc/vtkFunctionParser.cxx,
>>>> line 300
>>>> vtkFunctionParser (0x205ddac0): expecting either 2 scalars or a scalar
>>>> and a
>>>> vector
>>>>
>>>>
>>>> ERROR: In
>>>>
>>>> /home/abuild/rpmbuild/BUILD/ParaView-v4.0.1-source/VTK/Common/Misc/vtkFunctionParser.cxx,
>>>> line 201
>>>> vtkFunctionParser (0x205ddac0): Parse: Error deciding between ambiguous
>>>> operators
>>>>
>>>>
>>>> - Can you help me or tell me gow to visualize the stress tensor from the
>>>> displacement field?
>>>> - Alternatively you it would also be good to know how to multiply the
>>>> result
>>>> of  filter Gradient of Unstructured DataSet by a scalar value.
>>>>
>>>>
>>>> Many thanks for helping!
>>>> Gianna
>>>>
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>>>
>>>
>>
>>
>
>