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Help me with my cohesive elements simulation 1

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feifei1024

New member
May 31, 2012
5
Hi guys

I am currently doing my final year project, which is about simulating advanced sandwich structures. My aim now is to simulate the debonding between the facesheet and the foam. I have stayed in front of computer for 3 days and i couldn't solve my problem

I first create a single solid model and partition it with sections for facesheet and foam. After meshing, I create an orphan mesh and use the mesh edit tool to embed 2 zero-thickness cohesive layers on the interior surfaces. I assign the cohesive section based on seperation and traction response. The step module I used is static general type with time period 0.5, increment size: (0.001,5e-5,0.5). I used full integration, because I found when I used reduced integration, the artificial strain energy ALLAE is huge..

When I run my analysis, It always stops as the damage variables(SEDG) of cohesive elements reach to 1, though i have introduce the viscosity ~0.001. I want to get the full analysis as possible. I have tried number of different ways, the outcomes are still not satisfied. Any one can help me with this issue. I can send u my file if you want.

Thank you very much!!!! :)
 
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what are your cohesive and other material properties? When you say "Stop", does it mean you analysis runs but aborts? What are the reasons for aborting? excessive distortion? Do any of the cohesive elements fail?
 
** MATERIALS
**
*Material, name=CFRP
*Elastic, type=ENGINEERING CONSTANTS
130000.,9000.,9000., 0.26, 0.02, 0.02,4500.,4500.
4500.,
*Material, name=Cohesive
*Damage Initiation, criterion=QUADS
3.5, 1.3, 1.3
*Damage Evolution, type=ENERGY, mixed mode behavior=BK, power=1.
0.19, 0.57, 0.57
*Damage Stabilization
0.001
*Elastic, type=TRACTION
100000.,100000.,100000.
*Material, name=Foam
*Elastic
115., 0.3


Yes. the analysis runs but stops, it says too many attempts..
actually, i found that if the SEDG of just 1 element became 1, then the analysis stop? can you give me why this happens?
 
warning messages as:
Excessive distortion at a total of 65 integration points in solid (continuum) elements
 
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