Shear Thickening Composite for Shock Absorption
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Solution Overview
Problem
Current shock absorption materials, such as polyurethane and polystyrene foams, are inadequate in absorbing both large and small impacts, leading to potential long-term negative health effects due to their limited compressibility and inability to effectively mitigate g-forces from various sources of shock.
Innovation Solution
A composite material comprising a polymer matrix, such as a foam, impregnated with a non-Newtonian fluid that increases in viscosity with applied shear stress, providing enhanced shock absorption by transitioning from a soft to a stiffer state upon impact, thereby reducing impact acceleration forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If relatively hard and rigid foam materials are used for shock absorption, then the material can withstand larger impacts, but the material has limited compressibility and cannot optimally absorb smaller impacts
Solution Approach 1:
The foam material incorporates a non-Newtonian fluid that dynamically changes its viscosity based on applied stress. At rest, the fluid remains viscous allowing the foam to be soft and compressible for small impacts. During high-velocity impact, the fluid undergoes shear thickening, increasing viscosity and making the foam rigid to withstand large impacts. This dynamic property resolution allows the single material to adapt to both small and large impact conditions.
Solution Approach 2:
The invention changes the physical parameter of the fluid's viscosity through shear rate variation. The non-Newtonian fluid's viscosity is not fixed but varies with the shear rate applied during impact. This parameter change enables the foam to transition from a soft, compressible state during normal use to a hard, impact-resistant state during collision, resolving the contradiction between compressibility and impact resistance.
2Device complexity
If traditional polymer foams are used, then the material structure is simple, but the material cannot effectively absorb both large and small impacts
Solution Approach 1:
The invention creates a composite material system combining a foam matrix with a non-Newtonian fluid. This composite structure integrates two distinct materials with complementary properties: the foam provides the structural framework while the non-Newtonian fluid provides the adaptive shock absorption mechanism. The composite nature allows the material to effectively absorb both large and small impacts, improving reliability without excessive complexity.
Solution Approach 2:
The non-Newtonian fluid acts as an intermediary substance within the foam cells. During impact, this intermediary fluid undergoes shear thickening and transforms kinetic energy into viscous dissipation, effectively absorbing impact energy. The fluid mediates between the external impact force and the foam structure, enabling the material to handle both large and small impacts effectively.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite material significantly reduces initial impact and shockwave acceleration forces by up to 30% compared to traditional polymer foams, offering improved protection against a broader range of impacts while maintaining a soft, cushioned feel for user comfort.
Implementation Method 1
a non-Newtonian fluid (sometimes referred to as a shear thickening material or dilatant) incorporated therein
Implementation Method 2
The non-Newtonian fluid may have a viscosity in the range of about 60,000 cSt to about 1,000,000 cSt
Implementation Method 3
Shock absorption materials have utility in a wide variety of applications in which it is desirable to damp or mitigate undesirable shocks
Data Source
AI summary
A composite material with an elastic modulus of less than 0.1 MPa at 100% elongation including a polymer matrix and a non-Newtonian fluid is provided. The composite material may be employed in shock and impact absorption applications to reduce initial and shockwave acceleration forces. Methods of forming the composite material and reducing acceleration forces in an impact utilizing the composite material are also provided.