There is a vertical bar of height H, and we have varying temperature profile along the height, The curve is quite zig-zag. I have divided the curve into many parts and got the equation fitting each part. Then I have used the analytical field option to give the equation for each part. But as each equation is approximated, there is discontinuity at the point joining the two parts. (The temperature at that point should be the same, but as there are 2 different equations at that point, dr is discontinuity). Could anyone suggest how to solve this problem (other than writing a program)?
You can use the coupled temperature-displacement step (pay attention for the type of elements), than define a fixed temperature as the boundary condition only at extremum points of your zig-zag temperature profile. Temperature will be almost linearly interpolated between defined points and in that way you will get full zig-zag temperature field. Because of coupling, temperatures became automatically the load for structural analysis. Sometimes a lot of memory is needed.
Analysis can be decoupled as well (second solution) into two steps:
1. Pure thermal analysis with the boundary conditions as described above.
2. Output from thermal analysis (full temperature field taken from existing odb file) applied as prescribed thermal boundary conditions for pure structural analysis.
In that way thermal step is calculated only once and used for multiple structural calculations. In your case it's probably better.
Is the temperature gradient in your model due to the existence of a heat source on one side, resulting in a gradient in the sample? In that case it may be more practical to assign a thermal conductivity property to your elements and place temperature or heat source on a surface on one side and allow ABAQUS to calculate temperature change in your model.
The temperature gradient is due to the flow of coolant. The change in temperature is calculated using Thermal Hydraulics software. I have only the temp profile along the height.
I thinks you have to modify the equations of temperature. You have to obtain the same temperature (or close enough) in the common nodes, and them make only one equation valid to in the common nodes.
I am using the following method to apply temperature in multi-layered structure where temperature varies in two dimensional space like in a beam, the temperature varies along the length and thickness of the beam. (the temperature along the length for my problem can not be represented by one simple equation )
In abaqus, there is a coupled temperature-displacement model where the temperatures are applied as boundary conditions if the temperature along a surface is known (preferably at particular intervals of length or thickness). but this process involves little manual work.......If you know scripting, it becomes much easier.
First in material properties, thermal conductivity is specified (and also thermal co-efficient of expansion if structural load follows) the temperature at a particular location is given as the boundary condition . for example, in a rectangular domain, constraint the left and right or top and bottom surfaces by providing temperature as the boundary condiion.
You can use the coupled temperature-displacement step (pay attention for the type of elements), than define a fixed temperature as the boundary condition only at extremum points of your zig-zag temperature profile. Temperature will be almost linearly interpolated between defined points and in that way you will get full zig-zag temperature field. Because of coupling, temperatures became automatically the load for structural analysis. Sometimes a lot of memory is needed.
Analysis can be decoupled as well (second solution) into two steps:
1. Pure thermal analysis with the boundary conditions as described above.
2. Output from thermal analysis (full temperature field taken from existing odb file) applied as prescribed thermal boundary conditions for pure structural analysis.
In that way thermal step is calculated only once and used for multiple structural calculations. In your case it's probably better.
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