IMPACT RATE RESPONSE
Impact management materials currently used in helmets and protective equipment manage either rotational or linear energy - not both. In the case of helmets, these materials exceed the shear force properties of Jell-O like brain tissue. Furthermore, these other solutions depend on mechanical systems or rate dependent materials that are soft until stretched very quickly. Each has its own set of limitations in trying to meet the known response rates associated with brain soft tissue.
To truly be effective, the shape and duration of the acceleration curves that create stresses and strains in the brain tissue need to be managed for each sport or activity. To do so, the helmet materials have to respond to the rate and duration of shear for each type of impact event if it is going to protect against concussions.