1 Topic by djd (edited by djd 16-03-2010 04:23:54)

  • djd
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Topic: CCT Element

Hi, bp
I want to do a 3D linear static structure analysis. The model consists of a solid base with two thin-walled plates on it.  I found the CCT element in the element library munual, but I also found in it that a structure meshed by the CCT elements should be defined in x,y plane.  But the two thin-walled plates in my model are not in the same plane. Could I use the OOFEM 1.9 to solve my problem? Thank you!
What's more, could unit initial strain load be applied in OOFEM?
djd

2 Reply by bp

  • bp
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Re: CCT Element

Hi,

try use "rershell" element, which represent a shell element. It is based on combination of "cct" plate element and plane stress element. The advantage is that it can be arbitrarily positioned in space.  Please note, that this element has no rotational  degree of freedom corresponding to rotation around normal (more precisely, the is no stiffness corresponding to this DOF), so this has to be reflected in the model. This has been already discussed in this forum, see for example this post: http://www.oofem.org/forum/viewtopic.php?id=5

Concerning initial strain: this is generally supported, but I am not sure about the actual state for "rershell" element. I am currently out of office, I will check that later (It can happen, that I will forget, then please remind me to check this by posting a reply).

Thanks,
Borek

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3 Reply by djd (edited by djd 24-04-2010 05:22:47)

  • djd
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Re: CCT Element

Hi, Borek
I want to apply an uniform initial strain field(for example, the normal strain in x direction are 1, other components are 0) on the structure meshed by the PlaneStress2d element.  But I find OOFEM only supports the following structural load types.

    if ( !strncasecmp(aClass, "boundarycondition", 5) ) {
        newBC = new BoundaryCondition(number, domain);
    } else if ( !strncasecmp(aClass, "deadweight", 5) )   {
        newBC = new DeadWeight(number, domain);
    }
    //else if (! strncasecmp(aClass,"initialcondition",5))
    //   newBC = new InitialCondition(number,domain) ;
    else if ( !strncasecmp(aClass, "nodalload", 5) ) {
        newBC = new NodalLoad(number, domain);
    }

#ifdef __SM_MODULE
    if ( !strncasecmp(aClass, "structtemperatureload", 18) ) {
        newBc = new StructuralTemperatureLoad(number, domain);
    } else if ( !strncasecmp(aClass, "linearedgeload", 14) )     {
        newBc = new LinearEdgeLoad(number, domain);
    } else if ( !strncasecmp(aClass, "constantedgeload", 16) )     {
        newBc = new ConstantEdgeLoad(number, domain);
    } else if ( !strncasecmp(aClass, "constantsurfaceload", 19) )     {
        newBc = new ConstantSurfaceLoad(number, domain);
    } else if ( !strncasecmp(aClass, "usrdeftempfield", 15) )     {
        newBc = new UserDefinedTemperatureField(number, domain);
    } else if ( !strncasecmp(aClass, "tf1", 3) )     {
        newBc = new TF1(number, domain);
    } else if ( !strncasecmp(aClass, "pointload", 9) )     {
        newBc = new PointLoad(number, domain);
    }

None of them seems to serve my purpose. Of course,  I can use the temperature load and change the thermal dilation vector accordingly to reach my purpose.  But what I want to konw is, whether OOFEM supports the uniform initial strain field load type? If it does, what is the keyword to document this load in the data file?  Many thanks.
Yours, djd

4 Reply by bp

  • bp
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Re: CCT Element

Hi,

you can apply eigen strains directly using StructEigenstrainLoad.
This requires to use svn development version. After getting svn version, please have a look on
trunk/tests/sm/eigenstrain02.in for an example, how to prescribe eigen strains in plane stress analysis.

Borek

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