Additive Manufacturing Nozzle for Randomizing Composite Fiber Orientation
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Solution Overview
Problem
Controlling fiber orientation in liquified polymer matrices during additive manufacturing is challenging due to velocity gradients, leading to inconsistent alignment of fibers, which affects the properties of the final printed parts.
Innovation Solution
A nozzle design with a contraction region followed by an expansion region is used to dispense composite filament materials, inducing radial flow and randomizing fiber orientation, thereby achieving a target orientation that enhances shear strength and isotropic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a narrow channel is used to dispense the liquified polymer matrix, then the dispensing precision is improved, but the fiber orientation becomes inconsistent due to velocity gradients
Solution Approach 1:
The nozzle is segmented into multiple regions: a first region with a first cross-sectional area, a second region with a second cross-sectional area smaller than the first, and a third region with a third cross-sectional area larger than the second. This segmentation allows different regions to perform different functions - the second region provides high precision dispensing while the first and third regions control fiber orientation through controlled velocity gradients
Solution Approach 2:
The patent introduces a spatial dimension by varying the cross-sectional area along the flow direction. Instead of using a uniform narrow channel, the cross-sectional area changes through three distinct regions, adding a dimensional control mechanism that influences both dispensing precision and fiber orientation simultaneously
2Ease of operation
If the channel cross-sectional area is reduced to improve dispensing control, then the material flow control is improved, but the fiber alignment varies from 0° to 90° due to velocity gradients
Solution Approach 1:
The first region with the larger cross-sectional area is positioned upstream to preliminarily randomize fiber orientation before the material enters the second region. This preliminary action prevents severe fiber alignment issues in the dispensing region by pre-mixing the fibers in a more random configuration
Solution Approach 2:
The patent changes the geometric parameter of the channel cross-sectional area along the flow direction. By creating regions with different cross-sectional areas (first area > second area < third area), the velocity profile and shear stress distribution are modified to achieve both good flow control and random fiber orientation
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 nozzle design effectively randomizes fiber orientation, improving the shear strength and isotropic properties of the printed parts by allowing fibers to reorient from an aligned to a more random configuration, addressing the challenge of inconsistent alignment caused by velocity gradients.
Implementation Method 1
the tendency of the fibers to orient themselves lengthwise based on the velocity gradient across channels
Implementation Method 2
inducing radial flow and randomizing fiber orientation
Data Source
AI summary
A nozzle for dispense of a material that is a composite of fillers such as short fibers (e.g. carbon fibers) and a polymer matrix. The nozzle through which the composite material is dispensed has an expansion region through which the composite material flows. The expansion region dispenses a composite material wherein the fibers are substantially not aligned (e.g. in a random orientation with respect to each other in the polymer matrix).