Composite Shear Pin Joint for Aircraft Structural Reinforcement
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Solution Overview
Problem
Aircraft structures using composite materials face challenges with weight reduction, thermal expansion differentials, and maintenance needs due to the use of metallic components, and existing fastening methods are heavy and prone to corrosion, requiring additional safety measures.
Innovation Solution
A composite shear pin system with an adhesively bonded collar is used to reinforce structural joints in aircraft, providing redundancy and preventing separation of bonded components under shear loads, eliminating the need for metal fasteners and reducing maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic components are used to join composite structures, then structural strength and reliability are improved, but weight increases and corrosion resistance deteriorates
Solution Approach 1:
The patent applies homogeneity by using composite materials for both the structural components and the fasteners. The fasteners are made from the same or compatible composite materials as the components they join, creating a homogeneous composite structure throughout. This eliminates the need for metallic fasteners, reducing weight and eliminating galvanic corrosion while maintaining structural reliability through uniform material properties and matched thermal expansion coefficients.
Solution Approach 2:
The patent utilizes composite materials for the fasteners, specifically using fiber-reinforced polymer composites that provide both structural strength and weight reduction. The composite fasteners incorporate reinforcement fibers oriented to resist shear and tensile loads, while the polymer matrix provides corrosion resistance and bonding capability, thereby achieving both reliability and weight reduction simultaneously.
2Strength
If metallic fasteners are used in composite structures, then mechanical strength is improved, but maintenance requirements increase due to corrosion
Solution Approach 1:
By using composite fasteners made from the same material family as the structural components, the patent creates a homogeneous structure that is uniformly resistant to corrosion. This eliminates the galvanic corrosion that occurs between dissimilar metals and composites, significantly reducing maintenance requirements while maintaining the necessary mechanical strength through optimized fiber reinforcement.
Solution Approach 2:
The patent changes the material parameters of the fasteners from metallic to composite materials, specifically selecting fiber-reinforced polymers with appropriate fiber orientation and resin systems to achieve the required mechanical strength. This material parameter change provides both corrosion resistance and adequate strength, reducing maintenance needs.
3Weight of moving object
If composite materials are used throughout the structure, then weight is reduced and corrosion resistance is improved, but joint reliability may deteriorate without proper reinforcement
Solution Approach 1:
The patent employs composite fasteners with specifically engineered fiber reinforcement to maintain joint reliability. The fasteners incorporate continuous fibers oriented in directions that resist the primary load paths (shear and tension), ensuring that the composite-composite joints achieve reliability comparable to or exceeding metallic fastener connections while maintaining the weight and corrosion advantages of all-composite construction.
Solution Approach 2:
The patent utilizes collar geometries with curved or rounded features that distribute stress more evenly around the fastener-hole interface. This curvature prevents stress concentration that could lead to composite delamination or failure, thereby maintaining joint reliability in the all-composite structure.
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 composite shear pin system effectively reduces weight, minimizes corrosion concerns, and enhances safety by providing a failsafe mechanism against bond failures, ensuring reliable load transfer and structural integrity.
Implementation Method 1
A composite collar is bonded to the composite shear pin with an adhesive
Data Source
AI summary
A computer implemented method and apparatus for creating a structural joint for an aircraft. A first composite component and a second composite component are co-joined to form the structural joint for the aircraft. A hole through the first composite component and the second composite component is created. A composite shear pin is placed through the hole. A composite collar is bonded to the composite shear pin with an adhesive.