Undulating Substrate Peaks for Fatigue-Resistant Porous Coatings
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Solution Overview
Problem
Existing medical implant devices face challenges in achieving strong tissue ingrowth and resistance to fatigue failure due to notch formation and propagation, particularly in porous surface coatings.
Innovation Solution
A medical implant device with an undulating surface featuring peaks and recesses, where particles are bonded to the peaks and adjacent peaks, reducing notch initiation and propagation, and enhancing fatigue strength through a sintering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particles are sintered directly onto a planar substrate surface, then porous coating is formed for tissue ingrowth, but notch formation and propagation occur at the interface between particles and substrate
Solution Approach 1:
The substrate surface is segmented into multiple peaks and recesses rather than being planar. This segmentation prevents continuous notch propagation by creating discontinuities (recesses) that act as barriers to crack growth, thereby improving fatigue resistance while maintaining porous coating functionality.
Solution Approach 2:
The peaks and recesses structure acts as an intermediary between the planar substrate and the porous particle coating. This intermediary geometry modifies the stress distribution and prevents direct notch formation at the particle-substrate interface, resolving the harmful effect of notch propagation.
2Reliability
If aspherical particles are used to increase surface roughness and porosity, then bone tissue ingrowth is enhanced, but manufacturing complexity increases
Solution Approach 1:
Instead of making all particles aspherical (increasing overall complexity), the invention applies local quality by creating peaks and recesses only at the substrate surface. The particles themselves can remain simple spheres, while the localized surface geometry provides the necessary roughness and porosity for enhanced bone ingrowth.
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 device exhibits improved resistance to fatigue failure and enhanced tissue ingrowth, with reduced notch formation and propagation, leading to stronger fixation and increased durability compared to traditional implant devices.
Implementation Method 1
particles are bonded to the peaks on the surface of the substrate and adjacent particles are bonded to one another
Data Source
Figure 1~2
Figure 3
AI summary
A medical implant device comprises a substrate (10) having an undulating surface provided by peaks (12) which are separated by recesses (14). The device includes a porous coating layer provided on the undulating surface of the substrate which comprises a plurality of particles (16). The spacing between adjacent peaks on the surface of the substrate is less than the particle size of the particles. The particles are bonded to the peaks on the surface of the substrate and adjacent particles are bonded to one another.