TNT blast pressure

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­부지연 | 공과대학 공학교육혁신센터 | 장학조교 | 한양대(서울)

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Nov 5, 2025, 3:12:42 AMNov 5
to LS-DYNA2

Hello All

I am currently creating a model to measure pressure at a gauge located a certain distance from a concrete column after detonating TNT attached to the column.
For the blast modeling approach, I have adopted the Multi-Material Arbitrary Lagrangian-Eulerian (MM-ALE) method.

However, the measured pressure results show that the arrival time of the pressure is later and the peak pressure value is smaller compared to the actual experiment. 

What parts should I modify? 

I adjusted the TSSFAC value in CONTROL_TIMESTEP from 0.67 to 0.33, but there was no significant change. 

I also reduced the pressure measurement DT from 0.1 sec to 0.0001 sec, but it was ineffective. 

The keywords used include EOS_JWL, EOS_LINEAR_POLINOMIAL, CONTROL_ALE, ALE_MULTI_MATERIAL_GROUP, BOUNDARY_NON_REFLECTING, MAT_NULL, and MAT_HIGH_EXPLOSIVE_BURN. 

The air mesh size is 35mm, and when it was reduced below 25mm, the analysis time increased abnormally. 

What parts should I try to modify?  

Thank you very much for your time and support.

l...@schwer.net

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Nov 5, 2025, 8:31:01 AMNov 5
to ­부지연 | 공과대학 공학교육혁신센터 | 장학조교 | 한양대(서울), LS-DYNA2

1\ This sounds like a lack of mesh refinement. You should have a minimum of about 10 ALE cells across the radius (minimum distance) of your TNT charge to capture the blast initiation.

 

2\ What is the magnitude of the difference between measured and computed time of arrival and maximum pressure? Note: it is best to compare measured and computed impulse rather than maximum pressure.

 

3\ What is the mass of your TNT charge and the straight line distance to your point of measurement?

 

4\ What are your JWL EOS parameters for TNT and what is the reference for these values? Also please provide you MAT_HIGH_EXPLOSIVE_BURN parameters.

 

5\ Although likely not a factor in your present close in concerns, Note that BOUNDARY_NON_REFLECTING is not intended for air blast simulations. To eliminate boundary reflections you need to increase the mesh external dimensions.

 

                --len

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