Vesijäykkiöt

Vesijäykkiöt are a Finnish term referring to materials that exhibit a significant increase in viscosity or a phase transition to a more solid-like state upon rapid impact or shear stress, and return to a more liquid-like state when the stress is removed. These are a type of non-Newtonian fluid, specifically shear-thickening fluids. Their behavior is characterized by a dramatic change in consistency under duress, rather than a gradual change as seen in Newtonian fluids.

The underlying mechanism of vesijäykkiöt often involves the interaction of particles suspended in a liquid. Under normal conditions, these particles can move past each other freely, allowing the fluid to flow easily. However, when subjected to sudden force, the particles are rapidly pushed together, creating a temporary, entangled structure that resists further motion. This resistance manifests as a hardening or stiffening of the material. Once the stress is released, the particles can separate again, and the fluid resumes its more fluid state.

Common examples of materials exhibiting this behavior include suspensions of cornstarch in water, which is frequently used for demonstrations. Other applications are being explored in areas such as protective gear, where the material can stiffen upon impact to absorb energy, and in industrial processes where controlled flow and temporary solidification are beneficial. The precise formulation and particle characteristics determine the extent and speed of the shear-thickening effect.