Composite Spinal Fixation Rod With Fiber-Layer Bonding
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Solution Overview
Problem
Metal fixture rods for the spine cause magnetic interference during MRI imaging, and existing polymer-based rods face issues with unreliable bonding strength and stability.
Innovation Solution
A fixture rod design featuring a core member with exposed fibers and a reinforcing fiber layer, utilizing recesses on the core member surface to enhance bonding and rigidity, and incorporating materials like carbon, glass, or SiC fibers with a resin matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal is used as the fixture rod material, then fixing force and strength are improved, but magnetic field interference occurs during MRI imaging
Solution Approach 1:
The patent employs a composite structure consisting of a polymer core member reinforced with fiber layers (carbon, glass, or other high-strength fibers). This composite construction provides metal-level strength and rigidity while eliminating magnetic interference, as the polymer and fiber materials are non-magnetic. The fiber reinforcement compensates for the inherently lower strength of polymers, achieving the desired mechanical performance without the harmful magnetic effects.
2Object-affected harmful factors
If a polymer core member with adhesive bonding is used, then magnetic field interference is eliminated, but bonding strength between core member and covering layer becomes unreliable
Solution Approach 1:
The patent replaces adhesive bonding with a composite construction where fiber layers are integrated with the polymer core member. The fibers act as mechanical reinforcement that physically anchors the covering layer to the core, creating a structurally sound connection that does not depend on adhesive bonding reliability. This composite approach provides inherent mechanical interlocking and distribution of stresses.
Solution Approach 2:
The patent extracts and eliminates the adhesive bonding step from the construction process. By using a composite structure where fibers are embedded in the polymer matrix and extend through layers, the design removes the unreliable adhesive interface entirely, replacing it with direct mechanical integration through the fiber reinforcement.
3Strength
If fiber reinforcement is added to polymer core, then strength is improved, but bonding between core member and reinforcing fiber layer becomes difficult to achieve uniformly
Solution Approach 1:
The patent designs the fiber reinforcement as an integrated composite structure where fibers are embedded within the polymer matrix itself. This approach eliminates the need for separate bonding operations between discrete layers, as the fibers and polymer form a unified composite material. The uniform distribution of fibers throughout the polymer matrix ensures consistent reinforcement and eliminates bonding uniformity issues.
Data Source
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AI summary
Provided is a fixture rod having improved bonding strength between a core member and a reinforcing fiber layer, high rigidity, and high durability against a deformation load. The fixture rod according to one embodiment of the present invention comprises: a core member containing fibers; and a reinforcing fiber layer provided on the core member, and a part of the fibers of the core member is exposed from the core member, and a part of the fibers with the exposed part is embedded in the reinforcing fiber layer.