It's using shape memory alloys. Just to have some numbers, an alloy called Nitinol can recover strains up to ~6% after a phase transition. Nasa developed a device for rock splitting that use modified nitinol expanding elements that were capable of generating stresses in excess of 1.5 GPa at only...
Basically, I'm working on a project to make active compression garments instead of passive. There are a few materials that can actuate with large recoverable strains, and I want to use them to create the compression. I need to estimate how much pressure they could create based on the recoverable...