Zigzag Fiber Composite Structure for Aircraft Wing Hole Stress
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Solution Overview
Problem
Composite materials with holes are sensitive to stress concentrations, leading to reduced strength and the need for increased reinforcements, which counteracts their lightweight and strong advantages, especially in aircraft structures where load directions can cause discontinuities in fiber orientation.
Innovation Solution
A composite material structure with a peripheral region around holes featuring a zigzag pattern of continuous fibers, where the tensile and compressive rigidity is lower than in surrounding regions, allowing the main load-bearing area to absorb loads primarily, reducing stress concentrations and maintaining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcements are made by increasing the thickness of the plate around the holes, then stress concentrations are reduced, but the lightweight advantage is cancelled out
Solution Approach 1:
The patent applies different fiber orientations to different regions: 0° in the main body region and 45° or -45° in the peripheral region around holes. This local differentiation allows the peripheral region to better handle stress concentrations without requiring increased thickness, thus maintaining lightweight characteristics while improving strength around holes.
Solution Approach 2:
The patent changes the fiber orientation parameter from 0° in the main body to 45° or -45° in the peripheral region. This parameter change optimizes the composite material's response to stress concentrations at holes, allowing reduced thickness while maintaining strength.
2Strength
If fiber orientation is changed between peripheral region and other region, then stress concentrations are alleviated, but fiber continuity is broken causing strength drop
Solution Approach 1:
The patent introduces a resin layer as an intermediary between the peripheral region with 45°/-45° fiber orientation and the main body region with 0° fiber orientation. This resin layer acts as a mediator that bridges the fiber discontinuity, allowing load transfer between regions with different fiber orientations and preventing complete fiber breakage at the interface.
3Strength
If different fiber orientations are used in adjacent composite materials, then stress concentrations are reduced, but load transmission through resin is compromised
Solution Approach 1:
The resin layer serves as a mediator that enables load transmission between regions with different fiber orientations. It bridges the peripheral region (45°/-45°) and main body region (0°), allowing forces to be transmitted effectively despite the fiber orientation mismatch, thus maintaining both stress distribution benefits and load transmission capability.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The purpose of the present invention is to provide a lightweight composite material structure while suppressing a drop in strength. In a composite material structure, which is configured as a fiber-reinforced plastic composite material extending in one direction and having a plurality of holes (5) formed at intervals in a row in the one direction and which is subjected to a tensile load and/or a compressive load in the one direction, a peripheral region (3a) around the holes (5) comprises a first area (10) obtained by bending composite material, which is reinforced using continuous fibers that have been made even in the longitudinal direction, so that the center line of the width (W) of the composite material weaves between adjacent holes (5) and zigzags in the one direction. The tensile rigidity and/or compressive rigidity in the one direction of the peripheral region (3a) around the holes (5) is lower than the tensile rigidity and/or the compressive rigidity in the one direction of the other regions (3b) that surround the peripheral regions (3a).