Cold Worked Titanium Shock Strut Bearing Surface
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Solution Overview
Problem
Titanium shock strut components in aircraft landing gear assemblies suffer from poor tribological properties, leading to rapid wear due to friction, and existing coatings are environmentally undesirable and difficult to apply within space-limited areas.
Innovation Solution
The use of cold worked titanium as a bearing surface, which can be further modified through peening, honing, or burnishing, to enhance wear resistance and compatibility with non-metallic piston surfaces, thereby reducing weight and increasing service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If titanium is used for the main fitting to minimize weight and improve corrosion resistance, then weight and corrosion resistance are improved, but wear resistance deteriorates due to poor tribological properties
Solution Approach 1:
The patent applies a non-metallic bearing surface specifically at the bearing location where the piston contacts the main fitting, while the rest of the main fitting remains as titanium. This local modification provides improved wear resistance at the critical contact area while preserving the weight benefits of titanium throughout the entire structure.
Solution Approach 2:
The patent creates a composite structure by combining titanium (metallic material) with a non-metallic bearing surface material. This composite approach allows the shock strut to benefit from both the weight and corrosion resistance of titanium and the wear resistance of the non-metallic material at the bearing interface.
2Reliability
If a coating is applied to the titanium main fitting to improve wear properties, then wear resistance is improved, but environmental harm increases due to harmful chemicals used in coating processing
Solution Approach 1:
The patent replaces complex, environmentally harmful coating processes with a simpler non-metallic bearing surface integration approach that does not require harmful chemicals, thereby eliminating environmental harm while maintaining wear resistance improvements.
3Reliability
If thermal spray or HVOF systems are used to apply coating material, then wear resistance is improved, but device complexity and space requirements increase making coating difficult in space-limited areas
Solution Approach 1:
The patent extracts the bearing surface functionality from the metallic titanium surface and replaces it with a non-metallic material that can be integrated directly into the main fitting structure, eliminating the need for complex external coating equipment and simplifying the overall system.
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 cold worked titanium bearing surface improves wear resistance, reduces weight, and extends the service life of shock struts while maintaining the weight reduction benefits of titanium, providing improved tribological performance and compatibility with non-metallic surfaces.
Implementation Method 1
The inner surface of the cylinder includes a cold worked titanium bearing surface
Implementation Method 2
The cold worked titanium may be peened titanium, for example the peened titanium may be shot peened or laser peened
Implementation Method 3
The cold worked titanium may be burnished titanium, for example roller burnished titanium or low plasticity burnished titanium
Implementation Method 4
a piston that slides within the hollow cylinder to form a chamber within which a fluid can be compressed
Data Source
Figure 1
Figure 2~3
AI summary
A shock strut for a landing gear assembly that includes a hollow cylinder having a first bearing surface and a piston having a second bearing surface. The piston is configured to move within the hollow cylinder such that the second bearing surface slides relative to the first bearing surface. One of the first and second bearing surfaces includes a non-metallic material and the other of the first and second bearing surfaces includes cold worked titanium.