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Impact problem - complete part deletion on contact - need help

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Topic starter
(@harishameed)
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hello

i am simulating an impact problem. when the part comes in contact, complete part is deleted or disappears. I have attahced the k file. Need help. 

 

regards

 

Haris

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Negative Volume
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(@negativevolume)
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Hi @harishameed

It looks like your contact is *Contact_ERODING_surface_to_surface which is probably causing the issue. Is there a reason you are using the eroding part? If not, try *Contact_automatic_surface_to_surface

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(@harishameed)
Joined: 2 years ago

Unpaid Intern
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@negativevolume I tried using the *Contact_automatic_surface_to_surface but the result is same. there is no specific reason for selcting the *Contact_ERODING_surface_to_surface is because i am repeating this work published in an article and their this contact card was used. any other suggestion for it?

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Negative Volume
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(@negativevolume)
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@harishameed okay I see. Did that work publish what control cards they were using by any chance? And how experienced are you using LS-Dyna if you don’t mind me asking?

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(@harishameed)
Joined: 2 years ago

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@negativevolume no but they mentioned that this contact card was used. I am a student so learning  LSdyna but I am aware of basics n ran simple cases already. 

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Posts: 7
Topic starter
(@harishameed)
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Joined: 2 years ago

The screenshot of paper is attached for reference 

 IMG 20220702 211626
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Negative Volume
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(@negativevolume)
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@harishameed okay great to hear! We were all students at one time. They are using an eroding contact to represent the composite material being struck by a bullet. Did they provide the material properties of that composite? Between those and the lack on control cards would explain why you can’t get it to run

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(@harishameed)
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@negativevolume yes material properties are mentioned. I am attaching the reference paper. Thank you for your guidance. 

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Negative Volume
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(@negativevolume)
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@harishameed Unfortunately I’m on vacation without a computer so I won’t be able to help as much as I might normally be able to. 

Double check that your units are consistent. I saw a pretty wildly high velocity which might make sense for a bullet. Maybe even reduce the velocity substantially and lengthen the simulation time to check that your model is working without that high energy impact. Also try some of these suggestions

https://www.researchgate.net/post/Can-anyone-help-with-problems-modeling-bullet-impact-with-LS-DYNA

Ballistics simulations sound cool and lure a lot of beginners to try to run, but they are not easy to debug due to the complex material models required and the amount of energy present in the impact.

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(@harishameed)
Joined: 2 years ago

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Posts: 7

@negativevolume thanks for your kind suggestions. I am following your comments and trying to simplify the problem and proceed step by step now.  

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Negative Volume
Posts: 639
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(@negativevolume)
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Hi @harishameed

Did you make any progress on getting your model running?

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(@harishameed)
Joined: 2 years ago

Unpaid Intern
Posts: 7

@negativevolume Hello, Yes it is working now. The material properties in the reference paper were wrong. I first switched it to a simple material model (plastic kinematic) and then tweaked the materials model. Thanks for your concern and rememberance. Regards

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