Active Energy Absorber Using Shear-Thickening Fluid
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Solution Overview
Problem
Existing energy absorption materials face a 'conflict of stiffness,' where compliant materials are ineffective for large impact energies and stiffer materials are uncomfortable, and current technologies lack controllable, adaptive solutions for varying impact conditions.
Innovation Solution
The use of a shear-thickening fluid with controlled oscillatory deformation to vary viscosity, allowing for adjustable stiffness through transducers and sensors, enabling active energy management across a wide dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If compliant materials are used for energy absorption, then comfort is improved, but energy absorption capability deteriorates under large impact energies
Solution Approach 1:
The patent employs a shear-thickening fluid that dynamically changes its viscosity in response to applied stress. Under normal conditions, the fluid remains compliant and comfortable, but under large impact energies, it thickens to provide enhanced energy absorption. This dynamic property allows the material to adapt its characteristics based on the loading conditions, resolving the contradiction between comfort and energy absorption capability.
Solution Approach 2:
The invention utilizes a fluid whose viscosity parameter changes in response to stress conditions. By controlling the viscosity through stress-induced thickening, the material can transition from a compliant state (providing comfort) to a stiff state (providing energy absorption). This parameter change allows the same material to satisfy both requirements under different operating conditions.
2Strength
If stiffer materials are used for energy absorption, then energy absorption capability is improved, but comfort deteriorates
Solution Approach 1:
The shear-thickening fluid provides dynamic stiffness adjustment. Under normal use, the material remains soft and comfortable, but when subjected to large impacts, it rapidly increases its stiffness to absorb energy effectively. This dynamic behavior eliminates the need to choose between permanently stiff or permanently compliant materials.
Solution Approach 2:
The invention changes the viscosity parameter of the fluid based on stress conditions. By controlling the viscosity to increase under stress, the material achieves high energy absorption capability only when needed, while maintaining comfort during normal use. This conditional parameter change resolves the contradiction between stiffness and comfort.
3Device complexity
If passive activation mechanisms are used, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
The shear-thickening fluid automatically responds to applied stress without requiring external activation mechanisms. The material self-adjusts its viscosity based on the stress conditions it experiences, providing passive adaptability. This self-service mechanism maintains simplicity while achieving adaptability to different impact conditions.
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
This approach provides a comfortable and adaptable energy absorption system that can be tuned for different impact conditions, enhancing user safety and comfort in various applications, from protective gear to automotive safety.
Implementation Method 1
The use of a shear-thickening fluid with controlled oscillatory deformation to vary viscosity, allowing for adjustable stiffness through transducers and sensors
Data Source
AI summary
An impact absorber employs dilatant (shear responsive) fluid that is subjected to a controlled, low amplitude, high frequency oscillatory stress which controls the stiffness of the fluid. Piezoelectric transducers, voice coils, and other forms of transducers may be used to apply controlled vibratory stress to the fluid. The energy absorber may be used in protective body armor, medical devices such as splints and casts, vehicle safety absorbers and many other products which benefit from ability to control the stiffness of the energy absorber.