issue with initia impulse mine card

[PRAVEEN KUMAR]

Dear all
I am attempting to simulate explosive loading using the *INITIAL_IMPULSE_MINE card. This card has been applied to the segment set on the face of Plate-1, while the opposite face is fixed. A second plate (Plate-2) is positioned with a 10 mm offset. No contact has been defined between the two plates, and no loading has been applied to Plate-2.
However, in the simulation results, Plate-2 exhibits motion.
The schematics, simulation video, and .k file are attached for reference.
Please help me in identifying and resolving this issue.

[PRAVEEN KUMAR]

Simulation GIF

[lesz...@gmail.com]

 

You have only fixed but part not red on – fix it then it will not be able to move – or are there other issue ?

 

From: 'PRAVEEN KUMAR' via LS-DYNA2 <ls-d...@googlegroups.com>
Sent: Monday, September 8, 2025 12:02 PM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Re: issue with initia impulse mine card

 

Simulation GIF

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[l...@schwer.net]

Praveen –

 

Your rather odd modeling situation has demonstrated the need for the parameter SEARCH on keyword *INITIAL_IMPULSE_MINE

 

SEARCH -- Limit the search depth into the structure. Initial nodal velocity is distributed from the segment to a depth equal to the SEARCH value. The value must be positive. If set to zero, the search depth is unlimited and extends through the part(s) identified by PSID.

 

The applied impulse is NOT applied to only the segments in the associated set; impulse in this setting is Imp=mass*velocity.

Applying often large velocities to associated small masses leads significant element distortion. The developer decided instead to distribute the impulse through the thickness of the body “above” the segment set. For thin targets, e.g. plates this works well. However for thick targets, or cases like your with separated structures, a limit on the distribution of the impulse was needed. Thus the parameter SEARCH.

 

In your case, setting SEARCH to a number less than or equal to the thickness of your lower plate will prevent the upper plate from having impulse applied.

 

Below is a fringe plot of vertical (z) initial velocity with the parameter SEARCH=5

 

                              --len

 

 

 

From: 'PRAVEEN KUMAR' via LS-DYNA2 <ls-d...@googlegroups.com>

Sent: Monday, September 8, 2025 2:53 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>

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[Praveen Kumar]

Thanks for reply.
your solution genuine. 

But if i want to see impact between these two plates, I will assign contact between these plates and remove the spc of plate-1. 
but since, initial impuse mine is being applied to plate-2 without any selection or applying. the impact will not happen. 
i'm simulating it for impact case. 
this is just a example ( that load is being applied to plate-2 without applying even)
if you can help understand how to apply load to plate-1 only, it will be very helpful.
Thanks

[Praveen Kumar]

Thanks for replying
your solution is genuine for this case
The question is why plate 2 is moving even there is no load and no contact.
if i want to simulate impact in between two plates, it will not happen since load is being applied to both plates. 

On Monday, 8 September 2025 at 3:34:28 pm UTC+5:30 lesz...@gmail.com wrote:

[PRAVEEN KUMAR]

Thank you very much!
It worked.