Stent Link Segmentation for Stress Distribution
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Solution Overview
Problem
The stent disclosed in U.S. Pat. No. 7,264,633 has a configuration where stress concentrates on the link and its peripheral portion as the stent transitions between reduced and expanded diameter states, leading to a deterioration in shape accuracy.
Innovation Solution
A stent design featuring first and second struts with extension portions that extend along bisectors from both sides towards adjacent struts, and a bridge portion connecting these extension portions, which improves stress distribution and shape accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the link extends only from one side with respect to the bisector of the crest, then the device complexity is reduced, but stress concentration occurs on the link and peripheral portion leading to deterioration in shape accuracy
Solution Approach 1:
The link is divided into multiple segments: a first link extending from the first crest along its bisector, a second link extending from the second crest along its bisector, and a bridge portion connecting these links. This segmentation distributes stress across multiple components rather than concentrating it in a single link, thereby improving shape accuracy while maintaining reasonable structural complexity
Solution Approach 2:
The link structure is extended into the circumferential dimension by adding the bridge portion that connects links from adjacent struts. This dimensional expansion creates a more distributed stress pathway that prevents concentration at single points, resolving the contradiction between simple structure and shape accuracy
2Ease of manufacture
If the link extends only from one side with respect to the bisector of the crest, then the ease of manufacture is improved, but stress concentration causes deterioration in shape accuracy
Solution Approach 1:
By segmenting the link into separate components (first link, second link, bridge portion), each component can be manufactured using standard techniques and then assembled. This approach maintains ease of manufacture while the distributed structure prevents stress concentration that would compromise shape accuracy
Solution Approach 2:
The bridge portion merges the first and second links into a unified load-bearing structure. This combination allows stress to be distributed across multiple connection points while the individual links remain manufacturable using conventional methods
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 improved stent design enhances shape accuracy by reducing stress concentration on the link and its peripheral portion during diameter transitions, and also maintains the integrity of the coating layer and drug-elution effect.
Implementation Method 1
A stent according to any one of the first to third aspects, in which the first extension portion has an elliptical shape whose major axis is the first bisector, and the second extension portion has an elliptical shape whose major axis is the second bisector
Data Source
AI summary
The disclosure provides a stent including: an annular first strut forming a wave shape; an annular second strut that is adjacent to the first strut in the axial direction and forms a wave shape; a first extension portion that is formed on a first crest as some of plural crests protruding toward the second strut in the first strut and extends from both sides with respect to a bisector of the first crest toward the second strut; a second extension portion that is formed on a second crest, which is located to be shifted in a circumferential direction with respect to the first crest among plural crests protruding toward the first strut side in the second strut, and extends from both sides with respect to a bisector of the second crest toward the first strut; and a bridge portion bridged between the first extension portion and the second extension portion.