Learning Forum

[Mans Modig]

Hello!

As part of my engineering studies I am exploring new plugins that are part of Ansys. I am right now trying to learn LS Dyna. I'm trying to do a collision study of a winged drone colliding with different parts of a helicopter and had a few question as how my results can be evaluated.

First question regarding contact:

I am using a manual contact region where I bond the whole drone body to a (in this case) pitch link which is part of the main rotor system of a helicopter. I have used a frictional type of contact with friction coefficient of 0.3 (just assumption, drone is made of Expanded Polypropylene foam and the pitch link is made of structural steel). This is shown in picture 1, would this be a correct way to do it?

Second question regarding results:

Does picture 2 mean that the pitch link in this case penetrates the soft foam of the winged drone and the drone gets stuck?

I am using end time of 0,001 seconds for the simulations.

Is there any more things I should include in my setup that is not there right now? (picture 3) Just wondering if anyone knows some settings that are easy to forget when doing these simulations.

Thanks to however can help me with these questions :) Please contact me if any of my questions are too vague.

Kind regards,

A mechanical engineering student

[Armin]

 

Hi Mans,

Your setup looks good to me. If you have already defined all contact pairs manually, I would suggest deactivating “Body Interactions” since they sometimes interfere with manual contacts.
To check what happens after the impact, you can check the velocity of the drone after collision.

You have employed a proper tool (explicit solver of Ansys LS-DYNA) to evaluate this type of simulation. In general, explicit dynamics analysis is appropriate for short duration events that may include significant nonlinearities. To learn more about explicit dynamics analysis, check the following lesson:  Explicit Dynamics Theory – Ansys Innovation Course – YouTube

 

[Mans Modig]

Thank you for the response Armin!

After checking the velocity after impact I can see that it is not 0. Would it be better to use a higher end time? Using 0.001 s right now.

[Armin]

 

Thanks Mans.

Sure, you can increase the End Time to better observe the post-impact response. Doing so, if you faced a long solution time, look up a technique called “mass scaling” in explicit dynamics analysis that helps to reduce the computational time. You can refer to the course I shared with you earlier for a more detailed description.