Thin-Ply Carbon Composite Panel for Post-Buckling Aircraft Loads
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Solution Overview
Problem
Current structural panels for aircraft fuselages, particularly those using composite materials, fail to efficiently implement overcritical semi-monocoque design principles, leading to issues such as limited post-buckling operation, weight inefficiencies, and unreliable mechanical performance.
Innovation Solution
A structural panel with a composite skin made of thin carbon composite plies, each 0.02-0.05 mm thick, and a stiffening framework, featuring a quasi-isotropic layup and symmetrical or asymmetrical sub-laminates, allowing for a post-buckling factor greater than 2, achieving a quasi-isotropic behavior in tension, compression, and shear while maintaining consistent bending and torsional stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional composite skins with ply thickness not less than 0.25 mm are used, then manufacturing is simplified, but the skin gauge becomes too thick (0.5 mm or more) requiring very few plies which lacks robustness to ply orientation variations and reduces fracture mechanic performance
Solution Approach 1:
The composite skin is divided into many thin plies (0.02-0.05 mm each, totaling 10-30 plies for 0.5-1.5 mm thickness) rather than using fewer thick plies. This segmentation into multiple thin layers provides robustness against ply orientation variations and improves fracture mechanic performance while maintaining manufacturing feasibility through standardized thin-ply stacking sequences.
Solution Approach 2:
The patent uses carbon fiber reinforced plastic composite materials with a specific laminate structure comprising multiple thin plies arranged in quasi-isotropic or symmetric/antisymmetric configurations. This composite material approach enables both the desired mechanical performance and the required robustness while maintaining ease of manufacture through established composite fabrication processes.
2Strength
If composite skins with thickness 0.5-1.5 mm are used, then structural integrity is improved, but weight efficiency decreases compared to thin metallic skins operating in post-buckling regime
Solution Approach 1:
The patent changes the fundamental parameter of skin thickness to enable post-buckling operation. By using thin composite skins (0.5-1.5 mm) with carefully controlled ply configurations, the structure is designed to buckle at predetermined loads and then carry additional load through the post-buckling regime, achieving weight savings of 30% or more compared to both thick composite designs and metallic structures.
Solution Approach 2:
The composite skin employs different ply orientations and stacking sequences in different regions to optimize local mechanical properties. Quasi-isotropic layups provide uniform properties in all directions, while symmetric and antisymmetric sub-laminates are arranged to control buckling behavior and post-buckling performance, enabling weight-efficient design without compromising structural integrity.
3Reliability
If symmetric and antisymmetric sub-laminates are used, then quasi-isotropic behavior is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent employs specific ply thickness parameters (0.02-0.05 mm per ply) and stacking sequence parameters (10-30 plies total) to achieve quasi-isotropic behavior. By standardizing these parameters and using repeatable symmetric and antisymmetric sub-laminate patterns, the manufacturing complexity is managed while ensuring consistent mechanical performance across different panel configurations.
Data Source
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Figure 3A~3B
AI summary
The invention is related to a structural panel for use in aeronautical applications. The structural panel includes a composite skin (200) that comprises composite material and a stiffening framework that is rigidly attached to the composite skin (200). The composite skin (200) is configured as a load bearing monolithic structure (370) with a structure thickness (310) of less than 1 mm. The composite skin (200) comprises a composite laminate (480) with a plurality (400) of carbon composite plies (405). Each one of the plurality (400) of carbon composite plies (405) comprises a ply thickness (410) in a range from 0.02 mm to 0.05 mm.