Lattice Reinforced Radius Filler for Composite Stringers
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Solution Overview
Problem
Inconsistent performance and structural issues in composite aircraft stringers due to voids and thermal shrinkage, leading to cracking and separation of layers, which affect the load transfer and strength of the components.
Innovation Solution
A lattice structure made of connecting elongate members with a three-dimensional shape, filled with resin, is used as a radius filler to distribute loads effectively and reduce inconsistencies, providing improved performance and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a radius filler is used to fill voids in composite stringers, then the structural integrity is improved, but thermal shrinkage and stiffness inconsistencies cause cracking and separation of layers
Solution Approach 1:
The patent changes the physical and chemical parameters of the radius filler material to match the surrounding composite laminates. Specifically, the filler is made from the same fiber and resin materials as the laminates, with the same fiber orientation and resin content, ensuring consistent thermal shrinkage, stiffness, and strength characteristics during curing and service.
Solution Approach 2:
The invention creates a homogeneous structure by making the radius filler identical in composition and properties to the adjacent laminates. The filler uses the same fiber type, resin system, fiber orientation, and resin content, eliminating property mismatches that cause interface inconsistencies, cracking, and separation.
2Ease of manufacture
If traditional radius fillers are used, then voids are filled for manufacturing purposes, but the interface area between filler and laminates is susceptible to inconsistencies and cracking
Solution Approach 1:
The radius filler is manufactured with the same homogeneous composition as the surrounding laminates, including identical fiber material, resin system, fiber orientation, and resin content. This eliminates the interface property mismatch that causes inconsistencies and cracking, while maintaining ease of manufacture through consistent material processing.
3Weight of moving object
If composite materials are used to decrease aircraft weight, then payload capacity and fuel efficiency are improved, but voids and thermal shrinkage cause structural inconsistencies
Solution Approach 1:
The radius filler is constructed from composite materials identical to the surrounding laminates, using the same fiber-reinforced resin system. This ensures consistent mechanical properties, thermal shrinkage behavior, and strength characteristics, eliminating structural inconsistencies while maintaining the weight benefits of composite construction.
Solution Approach 2:
The invention carefully controls the material parameters of the radius filler to match the laminates exactly, including fiber type, resin composition, fiber orientation, and resin content. This parameter matching ensures that the filler integrates seamlessly with the composite structure, preventing cracking and separation while maintaining lightweight performance.
Data Source
AI summary
A method and apparatus for forming a radius filler. A lattice is formed of connecting elongate members having a three-dimensional shape of the radius filler. A resin is placed within the lattice.