Automated Fiber Placement with Pulsed Heating for Tight Curves
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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 is too tight.
Innovation Solution
An automated fiber-placement system comprising a dispenser, compactor, steering mechanism, and energy source that delivers pulsed energy to dispense and compact fiber-reinforced tape strips along virtual curvilinear paths, controlling temperature and geometry to maintain adhesion and orientation of fibers, even at tight radii.
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
Solution Approach 1:
The prepreg tow is segmented into discrete sections along its length, with heating elements applied at specific segments rather than continuously. This allows localized thermal expansion at curved sections to accommodate tight radii while maintaining adhesion at straight sections.
Solution Approach 2:
The physical state of the prepreg tow is changed through controlled thermal heating, which induces localized expansion and softening. This parameter change allows the material to conform to tight curves without peeling, then cools and solidifies to maintain adhesion after placement.
2Reliability
If continuous heating is applied to the prepreg tow, then adhesion is maintained, but the fibers cannot be oriented in complex orientations
Solution Approach 1:
The heating system is segmented into discrete heating zones along the tow path, allowing independent temperature control at different locations. This enables the tow to be heated only where curvature requires expansion, while remaining cool and stiff in straight sections for precise orientation control.
Solution Approach 2:
Heating is applied periodically at discrete intervals along the tow rather than continuously. The heating elements are activated in sequence as the tow progresses, providing periodic thermal expansion opportunities at curved sections while maintaining adhesion through controlled cooling between heating cycles.
3Reliability
If the prepreg tow is kept straight and parallel, then adhesion is maintained, but complex surface contours cannot be constructed
Solution Approach 1:
The heating system divides the tow into segments that can be independently controlled. Straight sections remain unheated and maintain their rigid, parallel configuration for adhesion, while curved sections receive localized heating to enable bending and contour formation.
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 complex surface contours and desired fiber orientations, overcoming the limitations of traditional AFP systems by preventing peeling and allowing tighter curvatures without compromising structural integrity.
Implementation Method 1
The energy source is configured to deliver a first quantity of pulsed energy and a second quantity of pulsed energy to a 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 automated fiber-placement method comprises delivering a first quantity of pulsed energy to first discrete portions of at least one fiber-reinforced tape strip, and delivering a second quantity of pulsed energy to second discrete portions of at least the one fiber-reinforced tape strip, alternating with the first discrete portions. The first quantity of pulsed energy heats the first discrete portions to a first temperature. The second quantity of pulsed energy heats the second discrete portions to a second temperature. The automated fiber-placement method further comprises laying down at least the one fiber-reinforced tape strip against a substrate along a virtual curvilinear path, such that (i) at least the one fiber-reinforced tape strip is centered on the virtual curvilinear path, and (ii) the first discrete portions are transformed into discrete tape-regions, geometrically different from the first discrete portions.