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Simulating Squeezed rubber ball

Posted: Fri May 29, 2009 10:03 pm
by mnabavi
Hi All,

I'm trying to simulate a rubber ball that's flexible and it's filled with water. The rubber ball will be squeezed by hand (to simulate that I'm just using two cylinders to simulate fingers!).
I used a soft body for my rubber ball.
Rigid body for my cylinders, and gave them an initial velocity in the -z direction.

The cylinders however go inside the rubber ball instead of squeezing it.

I've tried assigning a "solid" to my softbody, but the simulations crashes when I do that.

I've included two screen shots of my sim for the two cases of solid and non solid sphere.

Could anyone give me a hint on how to set up this simulation?

Thanks a lot in advance.


Attached files

Simulating Squeezed rubber ball

Posted: Sat May 30, 2009 10:50 pm
by matt_Johnson
You may want to just try animating these in maya first then import the .sd file into RealFlow.

ncloth is really good at simulating things like balloons so maybe you want to start there.

Are you just planning on showing water splashing around inside it or will the balloon burst at some point?

Simulating Squeezed rubber ball

Posted: Sun May 31, 2009 8:16 am
by mnabavi
Hello Matt.

Thanks for your reply. Unfortunately, I'm not familiar with MAYA or any other animation making software, which is why I wanted to do it in realflow.

The ball won't be burst off, the goal is to simulate a liquid like hot wax, inside a membrane, where the person can sculpt the liquid with hand and get the desired shape from it.

Do you know why I'm not getting a correct result?

Thanks. Maryam

Simulating Squeezed rubber ball

Posted: Sun May 31, 2009 8:58 pm
by matt_Johnson

There could be several reasons why your not getting the result you want.

Some things to consider:
Is stacking turned on?
What are your Min/Max substeps set to?
Try animating the cylinders vs. setting initial velocity.
The "crunching" your getting may be due to the collision distance of your rigids.
Try changing your spring assembly from cross to star. I've found that star is a little more reliable.

I quickly tried to create something similar and was able to get the sphere to flex when squeezed by the cylinders. Check out the two screen grabs below.

Attached files