Composite Tension-Shear Fitting for Aircraft Joints
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Solution Overview
Problem
Current metallic and composite fittings for aircraft structures are heavy, bulky, and inefficient in supporting tension, shear, and compression loads, requiring additional metallic parts that increase weight and manufacturing time, and fail to effectively absorb energy under compression loading.
Innovation Solution
A composite tension-shear fitting designed with a band, panel, and sheet configuration made of composite materials, featuring an inverted U-shape, U-shape, and inverted L-shape respectively, which can be secured together to form a single structural element capable of handling tension, shear, and compression loads, with cavities filled with pre-cured composite pieces for enhanced reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic fittings are used to support tension and shear loads at joints, then structural support is provided, but weight and bulk increase significantly
Solution Approach 1:
The patent employs composite materials (carbon fiber reinforced polymer) to manufacture the fitting, replacing traditional metallic materials. This composite construction maintains the required tensile and shear strength while significantly reducing the weight and bulk of the fitting, directly resolving the contradiction between strength and weight.
Solution Approach 2:
The patent integrates multiple functional elements into a single monolithic composite fitting structure. The fitting combines tension-load-bearing features, shear-load-bearing features, and compression-energy-absorption features into one unified component, eliminating the need for separate metallic parts and reducing overall weight while maintaining structural support capabilities.
2Reliability
If separate metallic parts are added to distribute loads efficiently, then load distribution is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent combines multiple load-distribution functions into a single integrated composite fitting. The fitting includes a first portion for tension loads, a second portion for shear loads, and a third portion for compression energy absorption, all manufactured as one monolithic structure. This eliminates the need for assembling multiple separate metallic parts, significantly reducing manufacturing time and cost while maintaining reliable load distribution.
Solution Approach 2:
The composite fitting is manufactured as a pre-integrated monolithic structure with all load-distribution features built-in during the composite molding process. This preliminary integration of multiple functions into a single component eliminates subsequent assembly steps, improving manufacturing efficiency without compromising load distribution reliability.
3Strength
If traditional metallic and composite fittings are used, then tension and shear loads are handled, but compression energy absorption is insufficient
Solution Approach 1:
The patent incorporates a specific third portion of the fitting with optimized local geometry and material properties designed for compression energy absorption. This portion features a geometry that promotes progressive crushing and energy dissipation under compression loads, while the first and second portions maintain optimal properties for tension and shear load bearing. This localized functional differentiation resolves the contradiction by providing specialized compression energy absorption capability without compromising tension and shear strength.
Data Source
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AI summary
An energy absorbing fitting is constructed to absorb tension, shear and compression loads at a joint between two composite material beams of a composite material frame. The fitting is constructed with a band of composite material having an inverted U-shape, a panel of composite material having a U-shaped cross-section configuration that is assembled into the inverted U-shaped configuration of the band, and a sheet of composite material having an inverted L-shape configuration that is secured to the band and to the panel. The fitting is positioned at the intersection of the beams and is secured to the joint between the beams, thereby reinforcing the joint against tension, shear and compression loads.