Rotor Mast Composite Insert for Weight and Crack Resistance
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Solution Overview
Problem
Traditional steel rotor masts are heavy due to the need for large safety factors to prevent catastrophic failure from latent material flaws, and shot peening only addresses exterior crack propagation, leaving interior surfaces vulnerable.
Innovation Solution
A rotor mast design featuring a metal outer member with a composite inner member that applies compressive force to prevent crack propagation, allowing for a thinner sidewall and acting as a redundant failsafe in case of outer member failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional steel rotor masts are designed with large safety factors to prevent catastrophic failure from latent material flaws, then reliability is improved, but weight increases significantly
Solution Approach 1:
The patent applies nesting by placing a composite inner member inside a metal outer member, creating a concentric dual-material structure. The composite insert is positioned within the metal mast body, with both materials working together to provide structural support. This nested configuration allows the system to achieve higher reliability through material diversity while optimizing weight by using lighter composite material in the inner region.
Solution Approach 2:
The patent directly applies composite materials by combining metal and composite materials in a single mast structure. The metal outer member provides strength and durability, while the composite inner member provides high strength-to-weight ratio and crack resistance. This composite approach allows the mast to achieve the required reliability without the excessive weight penalty of traditional homogeneous steel designs with large safety factors.
2Object-affected harmful factors
If shot peening is applied to the exterior surface of steel rotor masts to prevent crack propagation, then exterior crack resistance is improved, but interior crack propagation remains unaddressed
Solution Approach 1:
The patent applies local quality by providing different protective characteristics to different regions of the mast. The metal outer member with shot peening provides enhanced exterior surface crack resistance, while the composite inner member provides interior crack propagation resistance. Each material is optimized for its specific function and location within the mast structure.
Solution Approach 2:
The nested configuration allows the composite inner member to address interior crack propagation issues that cannot be solved by exterior shot peening alone. The composite material's inherent resistance to crack propagation in the interior region complements the shot-peened metal exterior, providing comprehensive crack protection throughout the mast volume.
3Weight of moving object
If the metal outer member is designed with thinner sidewall due to composite insert support, then weight is reduced, but structural complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the mast into distinct metal and composite segments. The metal outer member and composite inner member are separate components that can be manufactured independently using optimized processes for each material, then assembled together. This segmentation allows each component to be designed and fabricated for its specific functional requirements.
Solution Approach 2:
The use of composite materials enables the metal outer member to have a thinner sidewall while maintaining structural integrity. The high strength-to-weight ratio of composite materials allows for weight reduction in the metal portion without compromising overall mast strength, as the composite inner member compensates for the reduced metal thickness.
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
This design provides weight savings and improved safety by reducing the risk of crack propagation and enabling emergency autorotation landing in case of mast failure.
Implementation Method 1
a composite inner member that applies compressive force to prevent crack propagation
Data Source
AI summary
A rotor mast including an outer member defining a channel therethrough and an inner member disposed in the channel through the outer member, wherein the inner member is configured to apply a compressive force to the outer member.