Variable-Geometry Composite Fibers for Ballistic Slip Control
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Solution Overview
Problem
Composite structures face challenges in controlling fiber movement within the matrix during ballistic events, affecting both ballistic and optical performance, as the matrix failure allows fibers to move, leading to reduced resistance to penetration and optical distortion.
Innovation Solution
The composite article features fibers with varying geometry along their length, providing enhanced mechanical coupling between fibers and the matrix, as well as between adjacent fibers, which controls fiber slippage and movement, thereby improving energy absorption and resistance to impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fibers are embedded in a matrix to form composite structures, then load transmission and structural strength are improved, but fiber movement within the matrix occurs during ballistic events, worsening ballistic and optical performance
Solution Approach 1:
The fiber geometry is made non-uniform along its length, with varying cross-sectional areas that create localized regions of different stiffness and bonding characteristics. This local variation in fiber properties enhances mechanical coupling at specific locations, restricting fiber movement during ballistic events while maintaining overall structural strength
Solution Approach 2:
The cross-sectional area of fibers is varied along their length, changing the geometric parameter to optimize both load transmission and movement restriction. This parameter change creates a gradient in mechanical properties that simultaneously achieves strong load bearing and controlled fiber mobility during impact
2Use of energy by moving object
If fibers can move within the matrix, then some energy absorption occurs, but the area of optical distortion increases, worsening optical performance
Solution Approach 1:
By creating localized variations in fiber geometry, the energy absorption mechanism is concentrated in specific regions rather than distributed uniformly. This localized energy dissipation prevents widespread fiber movement that would cause extensive optical distortion, thus maintaining optical performance while still achieving energy absorption
Solution Approach 2:
The varying fiber geometry provides just enough mechanical coupling to restrict fiber movement to acceptable levels, rather than completely preventing movement. This partial restriction allows sufficient energy absorption while minimizing the area of optical distortion
Data Source
Figure 1~2
Figure 3~4
Figure 5A~6D
AI summary
A composite article may include a matrix (18) and a plurality of fibers (22) embedded in the matrix. Each one of the fibers has a fiber length (34) and a fiber geometry (32). The fiber geometry of at least a portion of the fibers may vary along the fiber length.