Variable Curvature Composite Gap Filler Preform Fabrication
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Solution Overview
Problem
Current gap fillers for composite materials have constant longitudinal cross sections, making it challenging to conform to complex contour composite parts with varying radii of curvature, which can lead to voids and reduced strength in joints.
Innovation Solution
A method and system that induce slip planes between fiber tows by applying different tensions, allowing for the creation of preforms with varying curvature along their length, enabling customized gap fillers that can be fabricated with changing radii of curvature, enhancing the strength of joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gap fillers are made with constant longitudinal cross section, then manufacturing is simplified, but they cannot conform to complex contour composite parts with varying radii of curvature
Solution Approach 1:
The gap filler cross-section is made dynamically variable along its length rather than constant. The preform is constructed with tows that can be independently positioned and sized at different locations, allowing the cross-sectional dimensions to change continuously to match the varying radii of curvature of the composite part being filled.
Solution Approach 2:
Different regions of the gap filler are given different cross-sectional dimensions tailored to local requirements. The preform allows each section to have customized dimensions that match the specific geometry of the gap at that location, rather than using a uniform cross-section throughout.
2Strength
If gap fillers are customized to match varying curvature, then joint strength is enhanced, but manufacturing complexity increases
Solution Approach 1:
The gap filler is segmented into multiple discrete tows rather than being a monolithic structure. These individual tows can be independently manipulated, positioned, and sized, allowing complex three-dimensional shapes to be built up from simpler one-dimensional elements through a modular construction process.
Solution Approach 2:
The fabrication system dynamically changes multiple parameters simultaneously including tow selection, tow positioning, tow tension, and cross-sectional dimensions along the length of the preform. This allows continuous variation of geometric parameters to match the varying curvature requirements while using a standardized fabrication process.
3Productivity
If traditional gap fillers are used, then manufacturing is economical, but voids and kinking occur in complex contour parts
Solution Approach 1:
The preform structure is designed to be self-conforming during resin infusion. The variable cross-section and flexible tow construction allow the gap filler to naturally adapt to the mold cavity geometry and resin flow patterns, eliminating the need for complex external constraints or manual adjustment to prevent voids and kinking.
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
The system allows for the automated fabrication of gap fillers with varying curvature, preventing voids and kinking, and enabling rapid, economical production of customized preforms that enhance the strength and bonding of composite parts.
Implementation Method 1
inducing slip planes between the tows of the bundle by applying different amounts of tension to each of the tows
Implementation Method 2
heaters configured to heat the bundle to a tacking temperature at which the tows bind together
Implementation Method 3
a cooler configured to reduce a temperature of the preform, thereby locking in a curvature of the preform
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Systems and methods are provided for fabricating preforms (714). One embodiment is a method comprising acquiring tows of fiber reinforced material (702), selecting a number of tows to utilize for a bundle having an aggregate shape (704), assembling the tows together into the bundle (706), curving the assembled tows by slipping the assembled tows with respect to each other (708), drawing the bundle through a die to bind the bundle into a preform, enforcing a longitudinally varying cross section along the preform (712), and locking in a curvature of the preform (714).