Open source Animation Content creation tools?

Question

Hi,

Are there any open source content creation tools that will help create rich animations (flash/html 5/windows based)? The end users will be non-computer savvy so it should be easy for them to work on it.

I am also willing to look at commercial versions, but if we have an open source software, it will be much easier to adapt it to our needs.

Some examples of content that needs to be created -

1. How mechanical gears work in an automobile
2. Internals of an IC engine
3. Digestion process in a human body
4. Plant processes such as mitosis

etc..

Thanks in advance..