Smoothing Pre-preg Composite Edges with Ultrasonic Vibration
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Solution Overview
Problem
The layup process of composite components using pre-preg layers results in 'ply drop-off' at the edges of adjacent layers, leading to sharp corners and stress concentrations, which are exacerbated with thicker layers.
Innovation Solution
A method involving the application of pressure and optional vibrational energy, such as ultrasonic energy, to the edges of pre-preg layers to smooth the ply drop-off, converting sharp vertical drops into gradual slopes and reducing the initial 90° angle to less than 45°.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fewer, thicker pre-preg layers are used to increase manufacturing efficiency, then productivity is improved, but ply drop-off becomes more severe and manufacturing precision deteriorates
Solution Approach 1:
The patent applies ultrasonic vibration to the edge of the second pre-preg layer to smooth the ply drop-off. The ultrasonic horn generates high-frequency vibrations that locally heat and soften the matrix material at the edge, allowing the fibers to redistribute and create a gradual slope instead of a sharp corner. This enables the use of thicker layers while maintaining surface quality and reducing stress concentrations.
Solution Approach 2:
The patent changes the physical state of the matrix material at the edge by applying ultrasonic energy, which temporarily reduces the matrix viscosity and allows fiber redistribution. This parameter change enables the edge to be smoothed without removing material or altering the overall layer thickness, thus maintaining manufacturing precision while allowing thicker layers to be used.
2Device complexity
If thicker pre-preg layers are used to reduce the number of layers, then device complexity is reduced, but stress concentrations increase due to severe ply drop-off
Solution Approach 1:
Ultrasonic vibration is applied to the edge of the thicker pre-preg layer to smooth the ply drop-off and eliminate sharp corners that would cause stress concentrations. The vibration-induced heating and fiber redistribution create a gradual transition in thickness, distributing stresses more evenly across the joint and eliminating the harmful stress concentrations that would otherwise be present at sharp edges.
3Manufacturing precision
If manual layup processes are used to ensure quality, then manufacturing precision is maintained, but productivity is reduced
Solution Approach 1:
The ultrasonic smoothing process is self-service in that it automatically smooths the ply drop-off at the edges of laid-up layers without requiring manual intervention. The ultrasonic horn is simply placed on the edge and activated, and the machine automatically performs the smoothing function that would otherwise require skilled manual labor, thus maintaining productivity while ensuring consistent quality.
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
This method effectively reduces stress concentrations and improves the aesthetic and mechanical properties of composite components by smoothing the ply drop-off, making it suitable for use with both thin and thick pre-preg layers.
Implementation Method 1
applying pressure and, optionally, vibrational energy to the edge of the second layer to thereby smooth the ply drop at the edge of the second layer
Implementation Method 2
applying pressure and, optionally, vibrational energy to the edge of the second layer to thereby smooth the ply drop at the edge of the second layer
Data Source
Figure 1a~1b
Figure 1c~2
Figure 3a~3c
AI summary
A method of manufacture of a composite component is provided, the method comprising the steps of providing two layers of pre-preg composite material, one of which has an edge adjacent a surface of the other. Pressure and, optionally, vibrational energy is applied to the edge to thereby smooth the ply drop.