Crack inside the geometry: how to partition and use the TIE constraint
Crack inside the geometry: how to partition and use the TIE constraint
(OP)
Hi,
I am trying to model a crack inside the geometry. Due to the loading applied to the outside boundary of the model i can't simplify the model into its half or even quarter part. I definitely want to model a crack line inside the geometry.
I have been told that i can do it through the TIE constraint.
I read up on that but i still have a few questions.
1) First of all, to partition the geometry how should i do?
Should i create two separate instances in the part (see attached file) or should i create one instance and partition it in the middle (see attached file) so that the crack faces = doubles nodes with the same coordinates?
2) When i want to use the TIE constraint. There are different options: Analysis default, node to surface, surface to surface. Which one is the most appropriate in my case.
3) In the TIE constraint you can specify a distance for the position tolerance. Does it means that all the nodes within that tolerance will be tied to the master surface even though they do not belong to the slave surface?
4) Since the TIE constraint stands for two glued surfaces i hope that the two tied surface will always have exactly the same shape?
Thanks,
Malik
I am trying to model a crack inside the geometry. Due to the loading applied to the outside boundary of the model i can't simplify the model into its half or even quarter part. I definitely want to model a crack line inside the geometry.
I have been told that i can do it through the TIE constraint.
I read up on that but i still have a few questions.
1) First of all, to partition the geometry how should i do?
Should i create two separate instances in the part (see attached file) or should i create one instance and partition it in the middle (see attached file) so that the crack faces = doubles nodes with the same coordinates?
2) When i want to use the TIE constraint. There are different options: Analysis default, node to surface, surface to surface. Which one is the most appropriate in my case.
3) In the TIE constraint you can specify a distance for the position tolerance. Does it means that all the nodes within that tolerance will be tied to the master surface even though they do not belong to the slave surface?
4) Since the TIE constraint stands for two glued surfaces i hope that the two tied surface will always have exactly the same shape?
Thanks,
Malik





RE: Crack inside the geometry: how to partition and use the TIE constraint
I ran a simple uniaxial tension model with two separate instances. As you can see on the pictures i tied the top and bottom surfaces, the top surface being the master surface.
As you can see in the results, the crack line doesn't remain exactly horizontal but is slightly waving along the horizontal line. Why ? It supposed to remain straight even after deformation...
Maybe i should rather create a crack surface with doubled nodes with the same coordinates but how can i do that?
Thanks for your help,
Malik
RE: Crack inside the geometry: how to partition and use the TIE constraint
Your mesh looks bad. You should use similar seeding approaches for both matching edges.
RE: Crack inside the geometry: how to partition and use the TIE constraint
corus
RE: Crack inside the geometry: how to partition and use the TIE constraint
You were right Xerf. I used similar seeding approaches for both matching edges and i got something nicer with the expected results. Actually it is even a requirement to make it work properly.
Corus: as you told me to do i created a circle around each crack tip and it worked great. Definitely the computed results clearly match the theoretical results.
But as you can see on the . ODB file that i attached to this reply, due to the "adjust slave surface initial position", the crack has not a symmetric deformed shape and thus its half bottom shape doesn't look really nice compared with the half top one. And i think that besides the mesh itself, this "fill the gap" may cause a loss of accuracy in the results.
So how can i do to get a symmetric shape? Should i inactivate the "adjust slave surface initial position" option?
Moreover i noticed in the results that when you want to compute the strain energy of the whole model the volume of the initial gap is actually included in the computation.
So how can i take advantage of that "adjust slave surface initial position" and at the same time get a symmetric crack shape and a computed strain energy that includes only the volume of the model at the very beginning.
Thanks for your help,
Malik
RE: Crack inside the geometry: how to partition and use the TIE constraint
You can create a rectangular partition encompassing the crack and use a structured mesh inside this partition.
RE: Crack inside the geometry: how to partition and use the TIE constraint
I am going to try it. Actually i used a symmetric contour and i seeded this contour by number but in the mesh control, i used a free mesh thinking that Abaqus could create a symmetric mesh on both sides but apparently i was wrong.
Actually i can't use a structured mesh: only the Free mesh is activated. I am using a "mesh on instance". Do you think that i'd better use a mesh on part?
Thanks,
Malik
RE: Crack inside the geometry: how to partition and use the TIE constraint
For example, if you partion a part by a rectangle (using partition by sketch) you can mesh the rectangle with a structured mesh.
Best.
RE: Crack inside the geometry: how to partition and use the TIE constraint
corus
RE: Crack inside the geometry: how to partition and use the TIE constraint
corus
RE: Crack inside the geometry: how to partition and use the TIE constraint