Stent Strut Fatigue Prevention via Restraining Means
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Solution Overview
Problem
Stents indwelled in affected body tissues face repeated bending stress, leading to strut breakage due to fatigue at the joining portion between the stent main wire and the strut, which compromises their long-term reliability.
Innovation Solution
Incorporating a restraining means in a non-joining portion near the joining portion of the stent main wire and strut to reduce bending fatigue by dispersing stress and limiting movement, thereby preventing strut breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stent is indwelled in an affected part, then it can treat the stricture or aneurysm, but the strut can be broken from the joining portion due to repeated bending fatigue
Solution Approach 1:
A restraining means is provided in the non-joining portion near the joining portion to restrain the stent main wire and strut before fatigue damage occurs. This restraining means acts as a preventive measure that limits the bending amplitude of the strut, thereby cushioning the joining portion from excessive bending stresses that would lead to fatigue breakage during long-term indwelled operation
Solution Approach 2:
The restraining means serves as an intermediary element between the strut and the joining portion. It mediates the bending stresses by restraining the non-joining portion of the stent main wire and strut, thereby protecting the critical joining portion from direct exposure to full bending amplitudes and reducing fatigue accumulation
2Adaptability or versatility
If the strut is allowed to move freely at the joining portion, then the stent can adapt to body movement, but the repeated bending causes fatigue and breakage
Solution Approach 1:
Different portions of the stent structure are given different degrees of freedom. The non-joining portion where the restraining means is provided has its movement limited to reduce fatigue, while other portions of the stent maintain their adaptability to body movement. This local differentiation allows the stent to preserve overall adaptability while protecting the critical joining portion from excessive bending
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
In a stent which joins a plurality of stent components by a strut, even when the repeated bending acts on the stent for a long period, the breaking of the strut can be prevented. In a stent 1 having a joining portion 7 which integrally joins a stent main wire 2 and a strut 4, the stent main wire 2 and the strut 4 are fitted into a restraining pipe 8 in a non-joining portion of the stent main wire 2 and the strut 4 near the end of the joining portion 7. The relative movement of the stent main wire 2 and the strut 4 is restrained. The amount of movement of the strut 4 relative to the stent main wire 2 can be decreased to reduce fatigue.