Composite Wing Structure Hole Stress Management
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Solution Overview
Problem
Existing composite-material structures with holes face stress concentration issues at circumferential edges, leading to increased weight and complexity due to the need for additional reinforcement methods like pins or stitches, which also affect productivity.
Innovation Solution
A composite-material structure where the holed structural member has lower tensile or compressive rigidity than adjacent structural members, allowing the adjacent members to bear the load and reducing the need for extensive reinforcement at the hole edges, with fiber orientations of +/-30° to +/-60° or preferably +/-45° to manage stress and load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a reinforcing layer is added to increase the thickness of the circumferential edge of a hole, then the strength at the circumferential edge is improved, but the device complexity and manufacturing complexity increase due to additional processes of applying pins or stitches
Solution Approach 1:
The invention changes the fiber orientation parameter in the composite material. Specifically, it uses fibers oriented at ±45 degrees relative to the longitudinal direction of the wing, which optimizes the stress distribution around the hole and reduces stress concentration without requiring additional reinforcement structures like pins or stitches.
Solution Approach 2:
The invention employs composite materials with specific fiber reinforcement patterns. By using unidirectional or multidirectional composite plies with optimized fiber orientations (including ±45 degrees), the structure achieves enhanced strength at the hole circumferential edge while maintaining a simple, integrated design without additional fastening elements.
2Strength
If pins or stitches are used to secure the reinforcing layer, then the strength at the circumferential edge is improved, but the productivity decreases due to additional manufacturing processes
Solution Approach 1:
The invention merges the reinforcement function into the main structural laminate itself. The same composite plies that form the wing skin also provide the reinforcement around the holes through optimized fiber orientation, eliminating the need for separate reinforcing layers and their associated fastening processes, thereby improving productivity.
Solution Approach 2:
By changing the fiber orientation parameter to ±45 degrees, the invention achieves both strength enhancement and manufacturing simplicity. This parameter change allows the structure to withstand stresses around holes effectively while being manufactured as a single integrated component without additional fastening steps.
3Strength
If the thickness of the circumferential edge is increased by adding a reinforcing layer, then the strength is improved, but the weight of the structure increases
Solution Approach 1:
The invention applies local quality optimization by varying the fiber orientation specifically in the regions around the holes (using ±45 degree orientations) while maintaining other orientations in the rest of the structure. This localized optimization provides strength where needed without uniformly increasing the weight of the entire wing structure.
Solution Approach 2:
The invention uses composite materials with strategically oriented fibers to achieve strength enhancement. The ±45 degree fiber orientations in specific plies provide the necessary reinforcement around holes while maintaining the lightweight characteristics of composite structures, avoiding the need for additional heavy reinforcing materials.
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 approach alleviates stress concentration at hole edges, simplifies reinforcement, and reduces the overall weight of aircraft components by distributing loads effectively, eliminating the need for additional reinforcement methods like pins or stitches.
Implementation Method 1
because stress concentration occurs at the circumferential edge of the hole, the strength at the circumferential edge of the hole needs to be enhanced
Implementation Method 2
composite materials made of fiber reinforced plastics (FRP: Fiber reinforced Plastics) are widely employed as high-strength, lightweight structures
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Provided is a wing the weight of which can be reduced, with consideration given to stress concentrations in areas around access holes. A wing (1) on which a tensile load is imposed in the longitudinal direction is provided with a center section (3b), a forward section (3a), and an aft section (3c). The center section (3b) is a holed structural member that is a fiber reinforced plastic composite material article which extends in the longitudinal direction and in which access holes (5) are formed. The forward section (3a) and the aft section (3c) are reinforced plastic composite material articles that extend in the longitudinal direction of the wing (1) and are connected to the sides of the center section (3b). The tensile stiffness of the center section (3b) in the longitudinal direction is lower than the tensile stiffness of the forward section (3a) and the aft section (3c) in the longitudinal direction.