Automated Fiber Placement with Pulsed Heating for Tight Curves
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Solution Overview
Problem
Automated fiber placement technologies face limitations in curving prepreg tows due to their high stiffness, which prevents them from being bent in-plane with a radius less than 300 inches, restricting the creation of complex surface contours and orientations in composite structures.
Innovation Solution
An automated fiber-placement system that delivers pulsed energy to discrete portions of a fiber-reinforced tape strip, allowing it to be geometrically transformed into spaced-apart regions, enabling the system to place fibers along tight curvilinear paths without peeling, and allowing for more complex surface contours and desired fiber orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If prepreg tows are placed with tight curvature radius, then complex surface contours can be constructed, but the prepreg tows peel away from the tool due to high stiffness
Solution Approach 1:
The prepreg tow is divided into discrete segments along its length, with heating elements applied at specific intervals. This segmentation allows different portions of the tow to be heated independently, creating localized soft zones that can navigate tight curves while maintaining adhesion at unheated segments.
Solution Approach 2:
The system applies periodic heating pulses to the prepreg tow as it is being placed. This periodic thermal action creates alternating zones of softened and rigid material, enabling the tow to conform to tight curvatures at heated zones while maintaining structural integrity and adhesion at cooler zones.
2Ease of operation
If continuous heating is applied to the fiber-reinforced tape strip, then the entire strip becomes soft and difficult to control, but tight curvilinear paths cannot be achieved
Solution Approach 1:
Heating elements are positioned at discrete intervals along the tape strip rather than providing continuous heating. This segmentation creates localized soft zones that can be precisely controlled to achieve tight curves at specific locations while maintaining rigidity and controllability in unheated sections.
Solution Approach 2:
The heating system provides non-uniform thermal distribution along the tape strip, with heat applied only at specific locations where curvature is needed. This local quality approach softens the material precisely where required for tight turning while leaving other portions rigid and easy to control.
3Ease of manufacture
If standard layup techniques are used, then manufacturing process is simple, but fiber orientations beyond 0°, +45°, -45°, and 90° cannot be achieved
Solution Approach 1:
The system dynamically controls the heating elements and steering mechanism to place fibers at arbitrary angles and orientations. By combining real-time heating control with programmable steerable placement, the system can achieve any fiber orientation required by the design while maintaining automated manufacturing simplicity.
Solution Approach 2:
The invention replaces the mechanical constraint of fixed-angle tooling with an automated steerable placement system guided by digital models. This substitution of mechanical fixtures with programmable automation enables arbitrary fiber orientations while maintaining ease of manufacture through software control.
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 tighter curvilinear paths and desired fiber orientations, overcoming the stiffness limitations of traditional AFP systems, and allowing for the creation of parts with properties not achievable with standard layup techniques.
Implementation Method 1
An energy source is configured to deliver a first quantity of pulsed energy and a second quantity of pulsed energy to leading side 114 of compactor 112 for respectively heating to a first temperature first discrete portions 124 of at least one fiber-reinforced tape strip 104 and, to a second temperature, second discrete portions 125 of at least one fiber-reinforced tape strip 104, alternating with first discrete portions 124 along at least one fiber-reinforced tape strip 104.
Data Source
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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 (104), and delivering a second quantity of pulsed energy to second discrete portions of at least the one fiber-reinforced tape strip (104), 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 (104) against a substrate along a virtual curvilinear path (128), such that (i) at least the one fiber-reinforced tape strip (104) is centered on the virtual curvilinear path (128), and (ii) the first discrete portions are transformed into discrete tape-regions (148), geometrically different from the first discrete portions (150).