3D Fiber-Reinforced Composite Riser Eliminates Delamination
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Solution Overview
Problem
Conventional archery risers face issues with delamination, exposed fiber ends leading to voids and decreased strength, and high friction surfaces due to mismatched material properties and machining processes, which affect the structural integrity and arrow trajectory.
Innovation Solution
A three-dimensionally fiber-reinforced composite riser is formed as a single unitary piece through a molding process, aligning fibers in all directions to absorb stresses and eliminate delamination and fiber pullouts, with integrated mounting features and smooth surfaces for reduced friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a spine is added to achieve desired structural integrity, then strength is improved, but delamination occurs due to mismatched physical and thermal properties
Solution Approach 1:
The invention removes the spine component entirely from the riser structure. Instead of adding a separate spine element that causes delamination issues, the patent uses a unitary molded composite construction where the entire riser is formed as a single integrated piece without requiring a spine, thereby eliminating the delamination problem while maintaining structural integrity through optimized fiber reinforcement.
Solution Approach 2:
The invention employs composite materials with fibers aligned in the directions of highest stresses throughout the riser structure. This use of directionally aligned composite materials provides the necessary structural integrity without requiring a separate spine, as the fiber orientation itself delivers the strength and stiffness needed while maintaining uniform material properties throughout the unitary construction.
2Ease of manufacture
If machining is used to achieve final shape, then manufacturing flexibility is improved, but fiber pullout and exposed ends occur leading to decreased strength
Solution Approach 1:
The invention replaces the mechanical machining process with a molding process. Instead of cutting and shaping the riser through machining operations that expose fiber ends and cause pullout, the patent uses injection molding or compression molding to form the final riser shape directly from composite preform, eliminating all machining operations and preserving fiber integrity throughout the structure.
Solution Approach 2:
The invention performs preliminary shaping of the composite material during the molding process itself. The riser is formed to its final shape and all features are created during molding, eliminating the need for subsequent machining operations. This preliminary action ensures fibers remain embedded and protected throughout the entire manufacturing process.
3Device complexity
If a two dimensional laminate structure is used, then manufacturing simplicity is improved, but fiber orientation is limited to plane stress conditions
Solution Approach 1:
The invention transitions from a two-dimensional laminate structure to a three-dimensional fiber reinforcement architecture. Fibers are positioned and oriented in all three geometrical dimensions including through the thickness direction, enabling the riser to withstand complex multi-axial stress states that occur during bow operation, rather than being limited to plane stress conditions.
Data Source
AI summary
The present invention relates to a three dimensionally fiber-reinforced riser and to the unitary or single-step methods of making the same. In one embodiment (a cross bow riser for example), the riser has an interior support with opposed side members and a front brace. The front brace has a depression centrally located therein. Two side ribs are also provided for structural support. Two pockets each optionally having a divider wall defining a top and bottom section are provided for receiving respective top and bottom pieces of a split limb, when a split limb is used. The riser can be made of a composite material having fibers aligned there within in the directions of the highest stresses for enhancing the structural strength of the riser. Other bow parts or components can likewise be made via composite material as well.