ShAKLE

Shock Absorbing Kinetic Liquid Encapsulation

Shakle (pronounced ˈSHak(ə)l )is a viscoelastic non-newtonian liquid that hardens upon receiving an impulse of kinetic energy.
In order to protect occupants from being bounced around and suffering injuries from quick accelerations, decelerations and impacts, modern power armor and robot vehicles often are equipped with liquid-filled compartments. But the liquid isn't just any old incompressible fluid like water or oil. The liquid found in high-tech power armors and robots is a special fluid that is a liquid at normal temperature, pressure and stresses. However, when subjected to rapid stresses associated with harmful impacts, the liquid hardens into a protective shell.

Utility

When impacted with kinetic energy, shakle heats up and becomes hard and brittle. The higher the impulse, the hotter, harder and more brittle it becomes. This prevents shockwaves from propagating within the liquid and harming the occupant. For these reasons, Shakle is used to fill the pilot compartments of larger forms of power armor and most robot vehicles. This protects the pilots from the enormous impacts associated with weapons fire, melee combat, and collisions and falls.

Inventor(s)

Invented by the Sorbothane corporation in the 21st Century for use in prototype power armor and extreme racing sports.

Access & Availability

Only the most advanced robot armors and power armors are equipped with shakle. The technology itself is not a secret, but the technological level required to implement it is so advanced as to make it prohibitively expensive to all but the most well-funded pilots.
Glitterboy Armors are equipped with the most advanced form of Shakle known in most of Rifts Earth, since it was formulated during the golden age of man prior to the great cataclysm.
Both the Coalition and Northern Gun in North America have their own versions of Shackle that is nearly as good. Northern Gun has a version of shackle that is specifically resistant to the acid spit of Xiticix. Triax (Germany) also has its own version of shakle.
The Republic of Japan uses a version of shakle even more advanced than that found in Glitter Boys. It has superior energy absorption properties equating to an additional +1 toughness by comparison. (this number is already included in the stats for RoJ robot and power armor)

Complexity

Shakle is not in itself a highly complex substance. Any amateur or hobbyist with a chemistry set can create it with access to the correct ingredients. However, the virtual reality rigs, control system interfaces and biological monitoring systems necessary to implement shakle are what makes its use so demanding.
There are also some proprietary versions of shakle that provide special performance, such as waste processing, fire resistance, acid resistance, vibration dampening, transparency-opacity, antibiotic, anesthetic, and shock absorbance.

Discovery

One of the most well known viscoelastic liquids in history is a substance commonly known as Silly Putty. A ball of silly putty can be bounced off the ground as if it were made of rubber, and will even crack if hit hard enough, but will ooze into a pool if let to sit. Shakle is based on the same concept, except it's natural state is far more fluid.
Shakle was invented in response to safety concerns regarding the safety of extreme racing vehicles. Harnesses and various neck and back supports had reached limits in how much safety they could provide without hampering the ability of the operator. The advent of virtual technology allowed operators to become fully encased in safety apparatus, but there was no good solution to also allow freedom of movement.
Shakle solved those problems by providing freedom of movement during normal operations while at the same time creating an absorbing, protective, fire resistant cocoon during crashes and emergencies.
The introduction of shakle revolutionized racing sports and opened up all new horizons in the realm of man-machine interface.
It was not long before the military also included shakle technology into their armored vehicles to enhance crew survival. This completely changed the design possibilities of military vehicles and eventually led to robot and power armor in the 22nd century in concert with advances in piezoelectric materials and adaptive control systems.