Airbag Inflate simulation

[importance-peak]

Hello, I'm struggling to simulate an airbag inflating in slow-ish motion.
The tricky part of the motion is that it unrolls from the packed position to the final inflated position

I have the model in final position and I tried:

• deflate it, add force field with spline to force it to roll inside and then inflate it back with vertex maps and fields
• just deflate it (with roll in) and playback the cache in reverse with some deformers
• use a animated mospline to drive a plane that drives the final mesh..

None of these really worked

If anybody has any ideas, pls share

[Dr. Sassi]

Hi importance-peak,

Air-bag can be from a car or in a life support back-back. Both are completely different

With this in mind, enrolling can mean many different things. You might have a clear idea about it.
Here is a link to a slow-motion capture of an unfolding Car-Airbag.
https://youtu.be/KRcajZHc6Yk?si=i5cYV6abqIOyWxhr&t=213
Is that what you are after?

If you have reference material or, better a storyboard, please share.

All the best

[Dr. Sassi]

P.S.: here are some initial ideas that fit to the video.

These are rough sketches…
https://projectfiles.maxon.net/Cineversity_Forum_Support/2025_PROJECTS_DRS/20251027_CV4_2026_drs_25_SKab_01.zip

Since I don't know the kind of Airbag, the following is brainstorming (But tested already)
As a side note, mixing and matching techniques might be an option. I saw that some car airbags are just pushed into a small, compressed "puck".
Think about a sphere that has all points. Move> Set Point Values> Points> Crumple. Just a little bit, then set the Overpressure to 0.01, created an Alembic. Then the same, but with greater Overpressure — perhaps 25 — another Alembic. The first one is reversed and covers the first half (negative Offset), then the second one is offset positively. This middle-as-startpoint approach might create better Quality.

The Backpack Airbags (AKA avalanche airbag backpacks) are folded by hand and more like an Accordion pleat, which surely creates a complex setup to reproduce.

Other Hybrid animations might be thinkable, such as Pose Morph and Balloon.

[importance-peak]

@Dr-Sassi
Yes, that reference is exactly what I'm after. I can't share more because of NDA but it s a car airbag.

Thank you for the sketches. I really need to look into the rigging approach. That s the only one I haven't tried.

The Pose Morph + Balloon kinda works, but as I morph with a linear field for ex, the cloth doens t handle well the transition period and in the final pose i don t need the cloth anymore. With a Jiggle deformer worked better.

I need to see how I can animate a joint rig that will roll inside but keeping the start and end of rig fixed

[Dr. Sassi]

Hi importance-peak,

You have created a helix, or spiral, sketch there. I haven't found any sources that show it that way. One source showed that airbags are pushed to a little "puck," while talcum powder helps reduce friction.
CV4_2026_drs_25_ANpm_01.c4d

Here is the simplest way so far that shows a pushed little package slowly unfolding.

Cheers

[Dr. Sassi]

Please have a look here as well, importance-peak.

Just some explorations.

The Spline Rail is perhaps one of the more overlooked options to shape or even animate forms
CV4_2026_drs_25_ANpm_21.c4d

This one was a rotoscoping from the video I linked above. I screen captured it, and placed it in the background, then Point Level Animated splines.
CV4_2026_drs_25_ANpm_31.c4d

Cheers

[importance-peak]

@Dr-Sassi
This last version, with the animated splines, is a great idea! Looks like the most art-directable approach.
Thank's a lot!

[Dr. Sassi]

You're very welcome, importance-peak.

The Car-Airbag is an interesting exploration.

Thanks for your feedback.

All the best

[Dr. Sassi]

P.S.: One more with some other ideas. Please let me know if there is anything that needs more information about.

Especially with a "twist" of the side areas…

CV4_2026_drs_25_SIhy_01.c4d

Cluster:
https://help.maxon.net/c4d/2026/en-us/Default.htm#html/OCACLUSTER.html

[importance-peak]

Thank you, I no idea about the Cluster modifier.

Right now i made to work with a rig and a jiggle effector for the main shape and the side panels are Cloth objects connected to the cached main mesh.

[Dr. Sassi]

That is a nice combination, importance-peak.

Thanks for sharing.

My best wishes for your project.