VCCT - Element not Fracturing

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  • Last Post 28 July 2019
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xavierBAM posted this 09 May 2019

Hello, I'm running a fairly simple Mode I fracture simulation on a beam with a special shape. I'm using the VCCT feature to "separate" the two halves of the beam. Everything works fine and the force convergence is good but when I go into the results I find this:

It's like if the nodes on the other edge weren't cracking. Honestly, I have no clue why this is happening, I´ve refined the mesh and the problem is still there. Since it's a Mode I fracture I only have Critical Mode I Energ Release Rate as a parameter I know for sure (from experimentation) ans it's very low, for Mode II and III I've used the same value but I was thinking of putting either a very big one or a very small one (0). 

The boundary condition is a fixed support on one side and a small displacement on the (Y) axis. I haven't set the pre-meshed crack as symmetric. Let me know how can I fixe this. Also, the Crack Length growth in all the percentages is always 0 mm, I assume because of this non-cracking nodes but in the middle it' shouldn't be 0.

Thank you

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xavierBAM posted this 10 May 2019

Hello, I've tried to fix it by saying that the Pre-Meshed Crack is symmetric and by turning the Weak Springs OFF but I've found that I run into this problem:

There is a collision between the two parts, I though that it was because I had suppresed the contact between the two surfaces but the same previous problem was already there. I´ve tried to turn ON the contacts the problem has dissapear but the side nodes are still not cracking and now the fracture gap is very thin (which I assume it's correct). I'm concerne that if turning the contact ON was the correct move and that if it may affect the results. Also, any idea on how to make the side nodes break?

xavierBAM posted this 10 May 2019

I've tried putting a Mode II and III Critical Energy rate to 0 and 10^5; I´ve established a contact in between the two surfaces and is still not working, some nodes on the side won't break and I don´t understand why. Can anybody give me a clue what am I doing wrong?

xavierBAM posted this 16 May 2019

Okey I've fixed it: the first thing it was a problem of assigning material: I'm using here a polymer but one of the body was still on structural steel. The second one I just had to turn on the contact.

vinod posted this 28 July 2019

Hi this is vinod I am trying to look at the crack growth in a bimetallic specimen but the crack is not working, but when I try for a single material it is working fine so my question is, is it not possible to perform pre meshed crack when I have two different materials in a single specimen it giving '?' side of smart crack can you help me with this.

 

 

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