Composite Lug Reinforcing Ring for Crushing Resistance
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Solution Overview
Problem
Composite material force transfer parts, such as landing gear side-braces, are prone to crushing and delamination due to stress concentrations at the lug's bore, limiting their ability to withstand mechanical forces in traction and compression.
Innovation Solution
A method involving a reinforcing ring made of discontinuous long fibers is inserted into the bore of a composite material lug, allowing for interpenetration with the lug's fibers and improved flexibility to absorb pin bending, enhancing the part's crushing resistance and reducing stiffness differences at the interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pin is used for pivot connection in a composite material lug, then the connection is achieved, but stress concentrations occur at the bore edges leading to crushing and delamination
Solution Approach 1:
The invention uses a composite reinforcing ring made of discontinuous long fibers embedded in a matrix material, inserted into the bore of the composite lug. This composite structure creates a gradient transition zone that reduces stress concentration at the bore edges while maintaining the lightweight properties of composite materials throughout the component.
Solution Approach 2:
The reinforcing ring is specifically placed in the bore region where stress concentration occurs, providing localized reinforcement without adding weight to the entire component. The discontinuous long fibers are oriented to provide strength in the critical stress zones while allowing flexibility in other directions.
2Strength
If a rigid reinforcing structure is added to the lug, then crushing resistance is improved, but flexibility to absorb pin bending is reduced
Solution Approach 1:
The invention changes the material parameters of the reinforcing ring by using discontinuous long fibers with specific length and orientation distributions, embedded in a matrix material. This creates a structure with intermediate properties between rigid and flexible, allowing the ring to provide crushing resistance while maintaining enough flexibility to absorb pin bending through controlled deformation of the fiber-matrix structure.
Solution Approach 2:
The reinforcing ring is designed as a thin-walled structure made of composite material that can flex slightly under load. The discontinuous long fibers provide reinforcement while the matrix material and fiber arrangement allow controlled flexibility, enabling the ring to absorb pin bending without compromising its crushing resistance.
3Strength
If continuous fibers are used in the reinforcing ring, then strength is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention uses discontinuous long fibers instead of continuous fibers, which are easier and cheaper to manufacture. The fibers can be randomly or semi-randomly oriented in the ring, simplifying the manufacturing process while still providing adequate strength through the high volume fraction of fibers and their length, which is sufficient to bridge stress concentrations without requiring precise alignment.
Solution Approach 2:
The use of discontinuous long fibers allows for a more homogeneous distribution of reinforcement throughout the ring structure, eliminating the complexity of aligning continuous fibers while maintaining consistent mechanical properties. The fibers can be evenly distributed in the matrix material, simplifying manufacturing processes such as resin transfer molding or compression molding.
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 solution significantly improves the force transfer part's ability to withstand crushing and prevent delamination, allowing for more effective use of composite materials in high-stress applications by distributing stress and maintaining structural integrity under traction and compression.
Implementation Method 1
The force transfer part thus benefits from local flexibility enabling it to absorb bending of the pivot connection pin that passes through the reinforcing ring
Implementation Method 2
the thermosetting resin may be selected from at least the following resins: epoxy type resins, cyanate-ester type resins, and polybismaleimide (BMI) resins
Data Source
AI summary
Provided is a method of fabricating a force transfer part including at least one lug made of composite material that is to receive a pin for making a pivot connection with another part. The method includes making a fiber preform for a main body of the part and making a preform for a reinforcing ring out of discontinuous long fibers, making the reinforcing ring preform to match the dimensions of at least one bore in the preform of the main body, inserting the reinforcing ring preform in the bore of the preform of the main body, and polymerizing the reinforcing ring and main body preforms in injection tooling. A force transfer part obtained by such a method is also provided.