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Temperature definition using fields in Three directions

prasad.guduguntla.external
Hello,
I need to define the temperature for 3D Cylindrical structure. The nodes are defined in Cylindrical Coordinate System and the temperature varies in ( R, Theta, Z ) in all three directions at interval of 25°.
The thickness of structures varies in Radial direction, because of that the R is not constant and it varies along the height.
 
I tried to create the fields by changing R  at each height using PATRAN, I am not able to define it .
 
 
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  • 0
    Please describe where your temperature profile comes from. Is it an equation or experimental data ? is it in regular ijk cylindrical increments so a hex mesh could be built with nodes at the measurement points and then the temperatures used as results for these to create a FEM field?
  • 0
    It's not a equation or experimental data, the nodal temperature at certain points are extracted from the thermal analysis.  These points are defined in Cylindrical CS.
    Now I need to consider these points in a  Nastran model and interpolate between the points.
     
    The temperature points are not directly at nodes of the FE Model.
    Yes at an interval of 22.5°
     
    Thanks
     
     
     
  • 0
    Yes, if they are at a regular arrangement then we can create a mesh purely for creating a fem field to map the temperature distribution from, and interpolate it onto the structural mesh.
    How many radial points do you have and how many layers?
    I will try to build a quick demo but if you can share your RTZ data point values I will try to use those.
     
     
  • 0
    I already got the FE Model  and temperature points.
    Now I need to define the field using these temperature points.
    It's 5 radial points.
     
    for example- (in Meters and Radians)
     
    Height    Radius  Angle Temperature
    1.0             2.1         22.5      200
    1.0            2.2         22.5     230
    1.0            2.3       22.5     300
    ……..
     
    If you still need the data, I can provide you tomorrow.
     
    Thanks
     
     
    ​
  • 0
    OK - First thing is to get familiar with using FEM fields for mapping.
    Here are a couple of references to articles that will help.
     
    For your data you will need to create a mesh that has the measurement points as its nodes.
    Assuming your measurement points are regularly spaced you can easily create cylindrical geometry in patran and mesh it so that you have the correct number of elements/nodes (topology) to match the measurement points. You can give this mesh properties that reference a dummy material id 1 and write out a nastran input file(bdf). You then need to adjust the geometry of the nodes to match your measurement points . An excel spreadsheet can be used to create GRID cards with the correct geometry and then export/save a copy as csv. Then you use these grid cards to replace those in the exported bdf. The csv data is like Free Format Nastran input, the files mygeom.xlxs and mygeom.csv reflect this). Note I used a cyl coord ID reference on the grids of 10000. This data was edited into the bdf file to make file cymap1.bdf.
    This bdf data can be read as a nastran input file into a new patran db to build the "temperature" model.
    The temperatures at the "temperature" nodes need to be put into a Patran2.5 nodal result file format. The file temps.nod is an example. Note this uses fortran style format (I8 for the node ID and E13 for the temperature) the help system will give more details if you need them, Take care changing the 144 number of nodes reference on the header card, ensure the columns of the other data don't change. The temperature data can be read into Patran using the "file / import / results / PATRAN2.nod" and you can use "pthermal_1_nodal.res_tmpl" as the template to specify what you are reading.
    After reading in the temperature "results" you can create a fringe plot of temperature on the "temperature" model and then with the fringe plot displayed go to "Loads/BCs" and then "LBC Fields" and use Create/Spatial/FEM with options Continuous and Scalar .
    Now you can read in the model you want to load and apply a temperature LBC to it using this field.
     
    There are lots of variations on this theme and which way you work them can be a personal choice or depend on other model factors. I won't try to anticipate these.
     
     
     
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