Goal
Provide a flexible, self-supporting material that absorbs impact energy while remaining comfortable and conformable.
Problem
Traditional impact protection (rigid plates, soft foams) is either inflexible or offers limited protection; a material that is both soft in normal use and rigid on impact is needed for body armor, sportswear, helmets, etc.
Concept Summary
A shear-thickening polymer composite consisting of a foamed elastomer matrix, a polymer-based dilatant (silicone-based, often borated siloxane), and a fluid (gas or liquid). Under low strain rates the material is soft and mouldable; at high strain rates the dilatant increases viscosity, making the composite stiff and capable of dissipating impact energy while remaining self-supporting.
Detailed Description
The invention (US20050037189) describes a self-supporting energy-absorbing composite made of (i) a solid foamed synthetic polymer matrix (preferably an elastomer such as polyurethane), (ii) a polymer-based dilatant distributed throughout the matrix (e.g., borated silicone polymer), and (iii) a fluid dispersed in the matrix (often a gas). The combination yields a resiliently compressible material that is flexible in normal use but becomes substantially rigid under high-rate deformation, providing superior impact protection and conformability to complex geometries. The patent outlines two embodiments - one with an open-cell foam matrix and another with a closed-cell foam - and discusses manufacturing methods, filler options, and potential coatings. The material has been incorporated into police body armour, sports helmets, and prototype "superhero" suits.
Principles
- Shear-thickening (dilatancy)
- Viscoelastic energy dissipation
- Fluid compression within foam cells
- Resilient compressibility
Scientific Domains
Materials
- Synthetic elastomer foam (e.g., polyurethane)
- Silicone-based dilatant (borated siloxane, polyborondimethylsiloxane)
- Fluid (gas or liquid dispersed in foam)
Mechanisms of Action
- Viscosity increase of dilatant under high strain rate
- Compression of fluid in foam pores
- Distribution of impact force over larger area
Applications
- Police and military body armour
- Protective helmets for skiing, snowboarding, cycling
- Impact-absorbing sports suits
- Packaging for delicate equipment
- Vehicle seat cushions
Claimed Performance
Potentially exceeds protection of current rigid systems while remaining flexible; self-supporting, resiliently compressible, and capable of conforming to complex geometries.
Experimental Evidence
Demonstrations of impact protection in police body armour, sports helmets, and a field test where the inventor was hit with a shovel while wearing a D3O-filled beanie and reported no pain.
Replication Status
Incorporated into commercial products such as police body armour and protective sportswear; multiple independent manufacturers use the technology.
Limitations
- Current prototypes are heavy and expensive for full-body suits
- Performance may vary with temperature and long-term aging
- Manufacturing complexity due to uniform distribution of dilatant and fluid
