Automated Fiber Placement Tow Segmentation for Tight Curvatures
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Solution Overview
Problem
Automated fiber placement (AFP) technologies face limitations in curving prepreg tows due to their stiffness, which restricts the creation of complex surface contours and orientations of unidirectional reinforcement fibers, leading to peeling issues when the radius of curvature is tight.
Innovation Solution
An automated fiber-placement system comprising a dispenser, compactor, steering mechanism, and energy source that delivers pulsed energy to fiber-reinforced tape strips, allowing them to be placed along virtual curvilinear paths with tight radii without peeling, by transforming discrete portions into geometrically different regions and controlling the orientation of unidirectional reinforcement fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If prepreg tows are curved in-plane with a tight radius, then complex surface contours can be constructed, but the prepreg tows peel away from the tool or substrate
Solution Approach 1:
The prepreg tow is divided into discrete segments along its length, with each segment independently controllable. This segmentation allows different portions of the same tow to have different curvature radii, enabling tight curves in some regions while maintaining adhesion in others by adjusting the curvature of individual segments
Solution Approach 2:
The system dynamically adjusts the curvature radius of prepreg tow segments in real-time during the placement process. By continuously varying the curvature along the tow length and during placement, the system can navigate tight contours without exceeding the peeling threshold at any point
2Ease of manufacture
If standard layup techniques are used with unidirectional reinforcement fibers, then manufacturing is simple, but desired fiber orientations for complex properties cannot be achieved
Solution Approach 1:
The reinforcement fibers are segmented into discrete controllable units along the tow length. Each segment can be independently oriented at different angles relative to the placement direction, enabling complex fiber orientation patterns (such as curved fiber paths or varying angles) while maintaining an automated layup process similar in simplicity to standard techniques
Solution Approach 2:
Different segments of the prepreg tow are assigned different fiber orientations based on local structural requirements. This allows each region of the composite structure to have optimally oriented fibers for its specific load conditions, achieving high adaptability while the automated system maintains ease of manufacture through centralized control
3Shape
If pulsed energy is delivered to transform discrete portions of fiber-reinforced tape strip, then complex surface contours can be achieved, but energy consumption increases
Solution Approach 1:
Pulsed energy is applied only to specific discrete portions of the prepreg tow that require geometric transformation for tight curves, rather than heating the entire tow continuously. This partial application of energy achieves the necessary shape changes while minimizing overall energy consumption by concentrating heating only where and when needed
Solution Approach 2:
The pulsed energy delivery uses periodic heating cycles with controlled duration and frequency, applying thermal energy in short bursts rather than continuous heating. This periodic action allows the prepreg material to be transformed at discrete locations while dissipating heat between pulses, reducing total energy consumption compared to continuous heating
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
Enables the construction of composite structures with more complex surface contours and desired fiber orientations, overcoming the limitations of standard layup techniques by maintaining adhesion and structural integrity even at tight curvatures.
Implementation Method 1
The energy source is configured to deliver a first quantity of pulsed energy and a second quantity of pulsed energy to the leading side of the compactor for respectively heating, to a first temperature, first discrete portions of at least the one fiber-reinforced tape strip and, to a second temperature, second discrete portions of at least the one fiber-reinforced tape strip
Data Source
AI summary
An article of manufacture comprises a strip that extends along and is centered on a virtual curvilinear path, comprising an arc, having an arc length and a radius. A ratio of the strip-width to the radius is greater than or equal to 0.003. The arc length is equal to or greater than a product of the radius and π/64. Within each of discrete strip-regions of the strip, one of the unidirectional reinforcement fibers that is closest to the first longitudinal strip-edge is more buckled than another one of the unidirectional reinforcement fibers that is closest to the second longitudinal strip-edge. Ones of the unidirectional reinforcement fibers that are buckled are parallel to a smallest one of virtual surfaces, joining the first longitudinal strip-edge and the second longitudinal strip-edge.