Hello,
Good day!
I am very new to Abaqus as well as to PBC concept. I would appreciate your help to learn both of them.
In a paper entitled "Applying Periodic Boundary Conditions in FEA" by Weidong Wu et. al. , the authors have applied PBC to a square steel plate. The applied PBC are :
u1left - u1right=0.01
u2top - u2bottom=0
Does that mean both the right and left edges will experience a displacement of 0.01? If so, why the U1 contour (attached below) is showing a value of +9.131e-03 at the bottom left corner and -1.833e-02 in the top right corner (none of the values are exactly 0.01, although they are close to it)? Could you please explain how the displacement is imposed on this body?
My another inquiry is, is it required to prevent rigid body motion to a unit cell which is loaded by PBC like the one described above?
Thank you!
"Does that mean both the right and left edges will experience a displacement of 0.01?"
No, it means that the difference in the displacement will be 0.01. If you do this for an RVE, the RVE is stretched by 0.01 in the x-direction, but nodes on different y-positions can move differently. (So a square can deform to a parallelogram, for example).
If you use Common plot options in the postprocessor, you can exaggerate the displacements to see how the deformation works.
The real periodic boundary conditions are u_i-x_j epsilon_{ij} should be equal on periodic edges. This requires one to create a mesh with corresponding nodes on the edges. You need to run six analyses corresponding to each global strain compnent epsilon_ij. For a 2D RVE, you can only get plane properties. For 3D properties, you need a 3D RVE. However if you use SwiftComp, you can completely get rid of boundary conditions, and do not have to worry about creating periodic mesh. You can get 3D properties out of 2D RVE, you only need to carry out one analysis. SwiftComp can be freely launched in the cloud at https://cdmhub.org/resources/scstandard, or used as a plug in for ABAQUS. All you need for SwiftComp is the finite element mesh with constituent properties you have already created.
https://cdmhub.org/resources/scstandard
Thank you Sir to both of you. Is there any way to verify if my output/result is okay or not after applying PBC? Also do I need to prevent rigid body motion of the RVE loaded under PBC?
Hello Dr. Yu, thanks a ton for your helpful feedback. I have gone through SwiftComp. The video tutorial is quite straight forward. I have a quick question.
I am interested to draw an RVE of hybrid composite, which will have two fibers with different diameters. Is it possible to draw it in SwiftComp?
Yes. You can either use the cloud version, following the manual regarding how to create user defined RVEs, or you can use ABAQUS-SwiftComp GUI. https://cdmhub.org/resources/1134 or ANSYS-SwiftComp GUI https://cdmhub.org/resources/1136. Then you can draw it using ABAQUS or ANSYS, but the GUI will call SwiftComp to perform the analysis, circumvementing all the difficulty about boundary conditions and much faster.
Hello Dr. Yu,
I have downloaded the Gmsh/calculix so that I will be able to run SwiftComp from my work-station. After drawing, applying material properties, applying PBC and meshing, whenever I am clicking on SwiftComp>Homogenization>Solid Model I am getting the following error in the cmd window. I have attached the error as an image. Could you please help me in this regard?
Thank you in advance!
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