Joint Stabilization Device Using Shear-Thickening Fluid
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Solution Overview
Problem
Current devices using dilatant fluids for joint stabilization often fail to provide adequate protection against non-physiological movements due to a decreasing restraining force with increasing joint angle, as the shearing force area reduces and the fluid fails to fill the vacated volume upon shear hardening, leading to insufficient injury prevention.
Innovation Solution
A device with a receptacle and a shearing body where the insertion opening is directed away from the shearing body attachment, allowing the shearing body to be pressed into the receptacle, increasing the effective shearing area and dilatant effect, thus enhancing the restraining force and movement damping, especially during non-physiological movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shearing body is pulled out of the receptacle during non-physiological movement, then the joint movement is limited by the dilatant effect, but the effective shearing area reduces and the restraining force decreases with increasing joint angle
Solution Approach 1:
The patent inverts the conventional pull-out mechanism by implementing a push-in mechanism. The shearing body is pushed into the receptacle during non-physiological movement instead of being pulled out. This inversion ensures that the effective shearing area increases with insertion depth, thereby maintaining and enhancing the restraining force throughout the movement range, resolving the contradiction between movement limitation and force maintenance.
2Reliability
If a high-viscosity dilatant fluid is used to provide strong protective effect, then injury prevention is improved, but physiological movements are restricted due to excessive resistance
Solution Approach 1:
The patent utilizes the shear-rate-dependent viscosity parameter of dilatant fluids. At low shear rates during physiological movements, the fluid maintains low viscosity allowing free movement. During non-physiological movements with high shear rates, the viscosity increases dramatically providing strong protective effect. This dynamic parameter change resolves the contradiction between stabilization and movement freedom.
Solution Approach 2:
The patent implements a dynamic protection mechanism where the restraining force adapts to the movement intensity. The dilatant fluid's viscosity dynamically changes based on the applied shear rate, and the push-in mechanism dynamically adjusts the effective shearing area. This dynamic behavior allows the device to provide appropriate resistance for physiological movements while strongly restricting non-physiological movements.
3Force
If the shearing body is pushed into the receptacle with increasing insertion depth, then the effective shearing area and dilatant effect increase, but the device complexity increases
Solution Approach 1:
The patent extracts the complex control mechanism from the system by utilizing the inherent properties of dilatant fluids and simple geometric constraints. The push-in motion is achieved through direct force transmission without complex actuators or control systems. The effective shearing area is extracted as a function of insertion depth rather than requiring active control, simplifying the overall device complexity while maintaining high restraining force.
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 device provides improved stabilization and protection by maintaining a stronger dilatant effect and increased restraining force with increasing insertion depth, effectively limiting joint movement and preventing injuries by using a low-viscosity fluid that shear-hardens only under load, allowing for smooth physiological movements while restricting non-physiological ones.
Implementation Method 1
Dilatant, shear-thickening materials, such as copolymer dispersions or copolymer fluids, which have a higher viscosity when high shear forces occur and a high gravity speed associated with them, are used for adaptive movement limitation.
Implementation Method 2
The greater the applied shear, the more viscous or viscous the fluid behaves. Correspondingly, shear-hardening or shear-thickening properties are also ascribed to dilatant fluids.
Data Source
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AI summary
The present invention relates to a device (1) for limiting a movement of a joint arranged between a first body part and a second body part, comprising a receptacle (2) that is held on the first body part by means of a receptacle fastener (29), a shear body (3) that is held on the second body part by means of a shear-body fastener (9) and is movable relative to the receptacle (2), wherein the shear body (3) is introduced at least partially into the receptacle (2) via an introduction opening (20), and a dilatant fluid (4), provided in the receptacle (2), for influencing a relative movement between the shear body (3) and the receptacle (2), wherein the introduction opening (20) of the receptacle (2) is directed away from the shear-body fastener (9).