Pushing a ball through a pipe using pressure. I need tips to get started

[husgutt]

Hi!

To get to know Abaqus, I've started a side project. I want to "shoot" a ball through a barrel/pipe using only pressure to propel it.

Any tips on what topics I should investigate and learn about? I just need some tips to get started.

I have:
- created an axissymmetric ball, and placed it inside an axissymmetric barrel with inner diameter equal to the balls diameter
- interaction defined between surface inside of barrel and surface of ball
- Penalty friction of 0.4
- Defined steel with elastic properties and assigned section to both instances.
- Meshed both instances


- Barrel has 0 mm disp. in inlet side through all steps to keep it from moving
- first step, the ball is displaced 2 mm (just to see that everything works)
- Second step, BC of ball is removed while inside the barrel
- third step, pressure is applied on the opposite side of the direction I want the ball to move.


Problems:
- Is static, general the correct type of step to use?
- When I remove the BC of the ball, and apply pressure, I get the error

"There is zero FORCE everywhere in the model based on the default criterion. please check the value of the average FORCE during the current iteration to verify that the FORCE is small enough to be treated as zero. if not, please use the solution controls to reset the criterion for zero FORCE."

I guess this is because there is nothing holding the ball back from propelling to infinity.

Is it possible to instead "fill" the chamber with pressure, as if the barrel is connected to an infinity large beholder of gas?


I'm really not sure how to go ahead from here.

Thank you for any input advice!

 

[rstupplebeen]

Since the ball an barrel are the same size there is no contact pressure to provide a reaction force. Try having the ball slightly larger so that the contact friction reacts against the pressure load. You can also look into 'volumetric pressure loading'. I don't currently have access to the help files otherwise I would point you to the section in the help files. I used this method In a presentation for Catia (COE) where I did an Abaqus simulation for fun. The CAE file and videos are located in DropBox off of my personal webpage.

https://sites.google.com/site/robertkstupplebeen/home/presentations/coe2013

I hope this helps.

Rob Stupplebeen

http://www.OptimalDevice.com

 

[husgutt]

rstupplebeen

Thank you!
I will have a look at this tonight after work!