Archery Bow Limb Support with Movable Fulcrum
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Solution Overview
Problem
Archery bow limbs often fail at the fulcrum due to high bending moments, as they are typically considered cantilever members with limited support beyond the fulcrum, leading to stress concentration and potential failure.
Innovation Solution
The design introduces a configurable archery bow with a limb support system that includes multiple support portions, allowing the fulcrum location to change as the bow is drawn, reducing the unsupported length of the limb and distributing stress more evenly by providing a continuous or discontinuous supporting surface that adjusts to the limb's shape, thereby reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the limb is supported only at the fulcrum location, then the bow structure is simple, but the unsupported length is long causing high bending moments and stress concentration at the fulcrum
Solution Approach 1:
The limb support is divided into multiple discrete support portions (first support portion, second support portion, third support portion) along the limb length. This segmentation provides multiple contact points that distribute the support function, reducing the unsupported length between supports and thereby reducing bending moments and stress concentration at any single location.
Solution Approach 2:
Different portions of the limb receive different levels of support. The first support portion provides support at one location, the second support portion provides support at another location, and the third support portion provides additional support further along the limb. This localized support distribution optimizes the structural performance by providing support exactly where needed to reduce stress concentrations.
2Device complexity
If the fulcrum location is fixed, then the bow design is simple, but the bending moment at the fulcrum is maximized leading to potential failure
Solution Approach 1:
The support system transitions from a static fixed fulcrum to a dynamic multi-point support system. As the bow is drawn and the limb flexes, different support portions engage at different stages. The limb can contact the first support portion, then the second support portion, and potentially the third support portion depending on the draw position, allowing the effective fulcrum location to move and adapt during the drawing cycle.
3Strength
If multiple support portions are added to the limb, then the stress distribution is improved, but the device complexity increases
Solution Approach 1:
Multiple support portions are integrated into a single unified limb support structure rather than being separate components. The first support portion, second support portion, and third support portion are combined into one cohesive support system that attaches to the riser as a single unit, reducing the number of separate parts and simplifying assembly while still providing distributed support.
Data Source
AI summary
In some embodiments, an archery bow is configurable between a first draw orientation and a second draw orientation. The bow comprises a limb and a limb support. The limb defines an unsupported length in either orientation, wherein the unsupported length of the limb is less in the second draw orientation than in the first draw orientation.