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3PB Impact Test

User: "Altair Forum User"
Altair Employee
Updated by Altair Forum User

Hi there,

 

I m trying to validate a 3 point bending simulation using a paper which presents both numerical and experimental data. I followed the exact same setup but the resultant force I keep getting is always 20% smaller than the one pretended. I've double-checked materials, properties, contacts and boundary conditions and nothing seems to change. I've tried the validation process with different papers and I always get the same problem. Any idea on what I might be doing wrong?

 

Thanks,

 

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    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Do you try to calculate with different mesh density?

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Yes. I've tried from 6mm characteristic length elements until 1mm and the solution appears to be well converged

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Yes. I've tried from 6mm characteristic length elements until 1mm and the solution appears to be well converged

     

    You say there're 20% different comparing to experimental results, but that's deformation or stress?

     

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Applied force over time

     

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    The deformation is imposed by the punch's constant velocity

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Maybe try to refine more your mesh?

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    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    I've figured it out. I had inertial problems due to poor sizing of the structure. The paper I am using considers the section's characteristic length as the inner dimension (to which you add the thickness) and not the average one. The section I was using was then undersized and therefore the bending force the beam was able to sustain was lower. 

     

    Thanks anyway! Using a more refined mesh is helping me reaching a better solution

    User: "Altair Forum User"
    Altair Employee
    OP
    Updated by Altair Forum User

    Always using a more fine mesh will give a better solution but will increase the solving time. So, keep the best element size which will give good results and meanwhile solves quickly.