Asymmetric Threaded Fastener Load Distribution
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Solution Overview
Problem
Conventional threaded fasteners experience uneven load distribution among threads, leading to a disproportionate load on a small portion of the threads, necessitating larger fasteners and increased manufacturing, maintenance, and repair costs.
Innovation Solution
The fastener features an asymmetrically threaded surface with varying effective diameters along its length, where the diameter changes from an intermediate position to the ends, ensuring that the ends have different effective diameters, thereby enhancing load distribution and reducing shear stress across threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pitch or distance between adjacent threads is reduced to increase the number of load bearing threads, then the load bearing capability is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies local quality by varying the pitch diameter along the length of the threaded fastener. The pitch diameter is smaller at the root and larger at the tip, creating different local properties that optimize load distribution. This allows the fastener to achieve improved load bearing capability without uniformly reducing pitch throughout, thereby avoiding increased manufacturing complexity.
Solution Approach 2:
The patent changes the geometric parameter of pitch diameter along the length of the fastener. By gradually increasing the pitch diameter from root to tip, the load is distributed more evenly across multiple threads. This parameter change achieves improved load bearing capability without requiring uniform pitch reduction, thus avoiding the manufacturing complexity associated with that approach.
2Strength
If the effective diameter of the load bearing end is reduced to distribute the load to threads further from the end, then the load distribution is improved, but the fastener size increases
Solution Approach 1:
The patent applies local quality by creating a gradient in pitch diameter along the fastener length. The smaller pitch diameter at the root and larger pitch diameter at the tip create localized properties that naturally distribute load to threads further from the end without requiring an overall increase in fastener length. Each section of the fastener is optimized for its specific loading conditions.
3Strength
If larger fasteners are used to achieve the desired holding force, then the load bearing capability is improved, but the manufacturing, maintenance, and repair costs increase
Solution Approach 1:
The patent changes the pitch diameter parameter along the length of the fastener to optimize load distribution. This allows the fastener to achieve the desired holding force with a smaller overall size compared to conventional uniform pitch fasteners. The gradient in pitch diameter enables more efficient use of material, reducing manufacturing costs while maintaining or improving holding force capability.
Data Source
AI summary
A fastener includes a threaded surface having an effective diameter. The effective diameter of the threaded surface changes along a first segment of the threaded surface. In addition, the effective diameter of the threaded surface changes along a second segment opposed to the first segment, and the change in the effective diameter of the threaded surface along the first segment is greater than the change in the effective diameter of the threaded surface along the second segment.