Composite Ankle-Foot Orthosis With Spiral Support and Flexibility
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Solution Overview
Problem
Existing ankle-foot orthoses (AFOs) lack sufficient support for both medial and lateral ankle portions, provide minimal foot support, are prone to material failure due to inflexibility, and have high manufacturing costs and variability.
Innovation Solution
An AFO constructed with a spiraling section using continuous fiber-reinforced thermoplastic composite (CFRTP) laminates, strategically embedded within a thermoplastic base material, allowing for injection molding to enhance strength, flexibility, and durability while enabling complex designs and easier fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If AFOs are made from hand lay-up carbon fiber to provide sufficient strength and flexibility, then the strength and flexibility requirements are met, but the construction becomes tedious and expensive
Solution Approach 1:
The patent uses composite materials consisting of a thermoplastic matrix material combined with continuous fiber reinforcement (such as carbon fiber, glass fiber, or aramid fiber) to achieve both strength and flexibility. This composite construction allows the AFO to meet mechanical requirements while enabling more efficient manufacturing processes compared to traditional hand lay-up methods.
Solution Approach 2:
The patent replaces the manual hand lay-up process with an injection molding process. The composite material is injected into a mold in a automated or semi-automated process, eliminating the tedious manual labor required for traditional carbon fiber construction while maintaining the necessary strength and flexibility properties.
2Strength
If AFOs are made from compression-molded carbon fiber to achieve sufficient strength, then the strength requirement is met, but the product becomes extremely stiff with little flexibility
Solution Approach 1:
The patent employs composite materials where the thermoplastic matrix material provides flexibility and comfort while the continuous fiber reinforcement provides strength and stiffness. By adjusting the fiber-to-matrix ratio and fiber orientation, the AFO can be tuned to have the right balance of flexibility and strength for different user needs.
Solution Approach 2:
The patent applies different fiber reinforcement densities and orientations to different regions of the AFO. Areas requiring higher strength (such as the ankle strut) have increased fiber content, while areas requiring flexibility (such as the footplate) have reduced fiber content or different fiber orientations, creating local variations in mechanical properties.
3Strength
If AFOs are designed with complex shapes like spiraling sections to provide adequate support, then the support function is improved, but balancing stiffness and flexibility becomes difficult
Solution Approach 1:
The patent uses composite materials that can be molded into complex three-dimensional shapes while maintaining controlled mechanical properties. The thermoplastic matrix allows for complex geometry fabrication through injection molding, while the continuous fiber reinforcement ensures adequate strength and flexibility balance in the spiraling and curved sections.
Solution Approach 2:
The patent incorporates curved and spiraling sections in the AFO design to provide adequate support and accommodate anatomical contours. These curved geometries are achieved through injection molding of thermoplastic composite materials, allowing the AFO to follow the natural contours of the leg and foot while maintaining structural integrity and flexibility.
4Reliability
If AFOs use thickening regions to prevent material breakage, then the durability is improved, but discomfort and additional weight are created
Solution Approach 1:
The patent uses composite materials with high strength-to-weight ratio, combining thermoplastic matrix material with continuous fiber reinforcement. This allows the AFO to achieve adequate durability and resistance to material breakage without requiring excessive thickening, as the fiber-reinforced composite structure provides strength efficiency that reduces the need for added mass.
Solution Approach 2:
The patent applies fiber reinforcement locally at critical stress points within the AFO structure rather than uniformly throughout. This targeted reinforcement strategy provides durability where needed while minimizing overall weight, as the continuous fiber reinforcement is concentrated in areas subject to bending and stress during normal use.
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 AFO offers improved strength, flexibility, and reduced manufacturing costs, with enhanced durability and repeatability, allowing for customizable fit and complex features like integrated buckles and adjustable stiffness.
Implementation Method 1
AFO constructed with a spiraling section using continuous fiber-reinforced thermoplastic composite (CFRTP) laminates
Implementation Method 2
allowing for injection molding to enhance strength, flexibility, and durability while enabling complex designs
Implementation Method 3
CFRTP laminates, strategically embedded within a thermoplastic base material
Data Source
AI summary
An ankle-foot orthosis forming a monolithic structure and include at least two different material components. The first material component has at least one tape layer consisting of a continuous fiber-reinforced thermoplastic composite, and a second polymeric material component surrounds at least in part the tape and includes a thermoplastic material into which the first material component is embedded. A resin material of the first material component is bonded to the second polymeric material component.