Fail-Safe Hinge Pin Assembly for Fracture-Resistant Load Transfer
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Solution Overview
Problem
Existing hinged assemblies in aircraft propulsion systems lack a fail-safe mechanism to maintain structural integrity and prevent failure due to thermal and vibratory stresses, which can lead to fractures in the hinge pins, compromising the connection between components.
Innovation Solution
A hinged assembly featuring an outer pin, an inner pin, and collars with fasteners that securely connect the components about an axial centerline, providing a fail-safe structural pin configuration where the inner pin acts as a backup to prevent fracture propagation in case of outer pin failure, and eliminating the need for anti-rotation features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single pin is used to connect components, then the device complexity is reduced, but the reliability decreases due to lack of fail-safe mechanism
Solution Approach 1:
The inner pin is nested within the outer pin, with the inner pin positioned inside a bore of the outer pin. This nested configuration allows the fail-safe mechanism to be integrated within the existing pin structure without significantly increasing external complexity, while providing redundant load-bearing capability if the outer pin fails
Solution Approach 2:
The pin connection is segmented into multiple independent pin elements (outer pin and inner pin) that can function independently. The collars are also segmented to secure each pin separately, allowing the system to maintain functionality even if one pin segment fails, thus improving reliability through functional segmentation
2Object-affected harmful factors
If traditional pinned connections are used, then the ease of manufacture is maintained, but the object-generated harmful factors increase due to fracture propagation under thermal and vibratory stresses
Solution Approach 1:
The inner pin is pre-installed within the outer pin structure before the assembly is subjected to thermal and vibratory stresses. This beforehand preparation ensures that if the outer pin fractures under stress, the inner pin is already in position to immediately provide structural support and prevent catastrophic failure, cushioning against the harmful effects of fracture propagation
Solution Approach 2:
The collars are positioned at specific locations along the pin assembly to provide localized reinforcement and stress distribution. The first collar secures the outer pin while the second collar secures the inner pin, creating local quality enhancements at critical stress points without requiring complete redesign of the entire assembly
3Ease of operation
If anti-rotation features are added to prevent loosening, then the reliability is improved, but the device complexity and difficulty of installation increase
Solution Approach 1:
The collar and pin configuration creates a self-locking mechanism where the geometric arrangement of the collar around the pin, combined with the fastening structure, automatically prevents rotation and loosening without requiring additional anti-rotation features. The system serves itself to maintain stability, eliminating the need for extra components that would complicate installation
Data Source
AI summary
A pin assembly is provided with an axial centerline. This pin assembly includes an outer pin, an inner pin, a first collar and a second collar. The outer pin extends axially along the axial centerline between an outer pin first end and an outer pin second end. The inner pin extends axially along the axial centerline within a bore of the outer pin. The first collar circumscribes the outer pin. The first collar is connected to the outer pin and the inner pin at the outer pin first end. The second collar circumscribes the outer pin. The second collar is connected to the outer pin and the inner pin at the outer pin second end.