RADIOSS BLAST SIMULATION

Andy@LamteqSolutions
Andy@LamteqSolutions Altair Community Member
edited October 2020 in Community Q&A

Hi all,

 

I've been tasked with a problem and need to get my head around LaGrange-Eulerian contact.

 

Overview.

I have a plate structure positioned over an explosive. The Structure is mesh size 10mm. The explosive, air and ground are eulerian elements 25mm size. 

 

Problem

When the explosive strikes the structure, one of two things occur. Either the volume fraction of explosive penetrates the plate  and the plate deforms (I find this occurs with Stfval = 38500, gap = 38) or the volume fraction of explosive does not penetrate the plate but the plate remains largely undeformed with very small displacement (I find this occurs with Stfval > 100,000, gap = 38). Am assuming speed of sound to be 3000m/sec (best I could find for explosive). To my mind, the volume fraction should not penetrate the plate. 

 

Am a bit puzzled by the apparent lack of deflection in the structure when the explosive hits the structure. Output for the contact is giving me approximately the same force in all cases - although higher values of Stfval are giving higher forces (between 6.5-8e6N). There does seem to by much more contact energy in the lower Stfval runs. So I am tad confused.

 

Any help would be much appreciated.

 

Andy

 

 

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Answers

  • Simon Križnik
    Simon Križnik Altair Community Member
    edited March 2020

    Hi,

     

    according to Radioss help this value should be calculated:
     

    <?xml version="1.0" encoding="UTF-8"?>stfac.jpg

  • Andy@LamteqSolutions
    Andy@LamteqSolutions Altair Community Member
    edited April 2020

    Many thanks for your reply Simon and sorry I didn't see this earlier.

     

    Yea, we're still having issues with this value... I'm getting 36800 using

    v = 3e6 mm/sec (TNT based number)

    p = 1.68e-9 Mg/mm^3

    Sel = 10x10 = 100 mm^2

    Gap = 38

     

    We have a test model which implies we need to be looking StFac 360 (as 36500 was barely making the component deform).. but when we apply that to another model the damage is vastly beyond what we would expect. 

     

     

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