Variable Radius Composite Filler for Asymmetric Cavity Inspection
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Solution Overview
Problem
Composite radius fillers in aircraft structures face issues such as reduced structural performance due to cracking, difficulty in non-destructive inspection, complex manufacturing processes, and high costs, particularly due to asymmetric shapes and variable inside radii.
Innovation Solution
A composite radius filler with a base portion and tip portion made of varying width composite plies, featuring a variable cross-sectional shape and a triangular tip portion formed from unidirectional slit tape tows, which can be manufactured to fit asymmetric cavities and improve structural integrity and inspectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional composite radius fillers are used, then they can fill the part cavity between web-flange transitions, but they exhibit reduced structural performance due to susceptibility to cracking and low pull-off strength
Solution Approach 1:
The radius filler is divided into multiple discrete composite plies stacked together to form the filler structure. Each ply can be independently manufactured and positioned, allowing for optimized fiber orientation and stress distribution that reduces cracking susceptibility while maintaining pull-off strength.
Solution Approach 2:
The radius filler is constructed from composite material plies with specific fiber orientations and stacking sequences designed to enhance both strength and reliability. The composite structure allows tailoring of mechanical properties to resist cracking while maintaining high pull-off strength at the bond interface.
2Strength
If radius fillers with variable inside radii are used to match asymmetric cavities, then they can improve structural performance, but they prevent non-destructive inspection using acoustic inspection methods
Solution Approach 1:
The radius filler employs variable inside radii at specific locations to match asymmetric cavity geometries and optimize structural performance, while maintaining constant width dimensions along the lengthwise direction. This localized variation allows acoustic inspection methods to effectively examine the filler-stringer and filler-skin panel bonds without being obstructed by complex variable geometry throughout the entire structure.
3Adaptability or versatility
If multiple components are assembled to form the radius filler, then complex asymmetric shapes can be achieved, but manufacturing cost and schedule are adversely impacted
Solution Approach 1:
The radius filler is segmented into multiple plies that can be manufactured using standard composite manufacturing processes and then stacked together. This approach allows complex asymmetric shapes to be achieved through the stacking sequence and orientation of individual plies rather than requiring complex tooling or multiple separate components, thereby reducing manufacturing cost and schedule.
4Adaptability or versatility
If multiple components are assembled to form the radius filler, then complex asymmetric shapes can be achieved, but manufacturing time and complexity increase
Solution Approach 1:
Individual composite plies are manufactured and prepared in advance using standard processes, then stacked together to form the complete radius filler structure. This preliminary preparation of discrete plies allows for efficient assembly and reduces on-site manufacturing time, improving productivity while maintaining the ability to create complex asymmetric shapes.
Data Source
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AI summary
A composite radius filler (200) include a base portion (238) and a tip portion (220). The base portion (238) is formed of composite plies (258) varying in overall width along an overall lengthwise direction (202) and defining a variable cross-sectional shape of the base portion (238) along the lengthwise direction (202). The base portion (238) includes at least one transition zone (294) having a transition start (296) and a transition end (298) along the lengthwise direction (202). The composite plies (258) of the base portion (238) are arranged in one or more stacks (250) each stack having a predetermined fiber orientation angle (262) sequence and a stack width (278, 282) that changes within the transition zone (294). The tip portion (220) includes a plurality of composite plies (258) formed into a generally triangular cross-sectional shape and stacked on top of the base portion (238).