Prepreg Sheet Gaps Suppress Wrinkles in Composite Molding
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Solution Overview
Problem
The movement of tape-like prepregs during press molding is hindered by adjacent tapes, leading to wrinkles and fiber meandering in stereoscopic molded articles, which impairs the strength and appearance of the final product.
Innovation Solution
A prepreg sheet is developed with laminated unit layers containing gaps between adjacent prepreg tapes, where the gap width is between 0.1% to 10% of the tape width, allowing for improved resin flow and reduced fiber restraint, thereby preventing wrinkles and meandering during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple tape-like prepregs are arranged closely together to form a continuous sheet structure, then the structural integrity and continuity of the prepreg sheet is improved, but the movement of prepreg tapes during molding is hindered causing wrinkles and fiber meandering
Solution Approach 1:
The prepreg sheet is segmented into multiple unit layers, each containing prepreg tapes arranged with specific gaps. This segmentation allows each layer to independently manage the balance between structural integrity and movement freedom, resolving the contradiction by creating discrete functional zones within the overall sheet structure.
Solution Approach 2:
Different unit layers are designed with different gap widths between prepreg tapes. Some layers have smaller gaps for structural stability, while others have larger gaps for movement freedom during molding. This local differentiation allows each region to optimize for its specific function, resolving the contradiction between structural integrity and movement freedom.
2Ease of manufacture
If gaps are introduced between adjacent prepreg tapes to improve resin flow and reduce fiber restraint, then molding properties are improved, but the structural continuity of the prepreg sheet is reduced
Solution Approach 1:
The gap structure is implemented in the planar dimension between tapes, while structural continuity is maintained through the vertical lamination of multiple unit layers. This dimensional approach allows gaps to provide molding freedom without compromising overall structural integrity, as the layers work together to maintain sheet stability.
Solution Approach 2:
The gap width between prepreg tapes is precisely controlled within specific ranges (0.01 to 10 mm, preferably 0.05 to 5 mm). By optimizing this parameter, the invention achieves the right balance between allowing sufficient resin flow and movement freedom while maintaining adequate structural continuity of the prepreg sheet.
3Manufacturing precision
If the gap width between prepreg tapes is increased to allow better resin flow, then fiber meandering is reduced, but the structural strength of the prepreg sheet is reduced
Solution Approach 1:
The prepreg sheet is divided into multiple unit layers with controlled gaps, allowing each layer to contribute to fiber alignment while maintaining overall structural strength. The segmented structure enables resin to flow through gaps without causing excessive fiber displacement, thus preserving fiber alignment precision while maintaining structural integrity.
Solution Approach 2:
The gap width is optimized within specific ranges (0.01 to 10 mm, preferably 0.05 to 5 mm) to achieve the right balance between resin flow and structural strength. This parameter optimization ensures sufficient space for resin infiltration and fiber movement freedom while maintaining adequate structural continuity and strength of the prepreg sheet.
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 prepreg sheet effectively suppresses wrinkles and fiber meandering, enhancing molding properties and resulting in a fiber-reinforced composite with excellent appearance and mechanical properties.
Implementation Method 1
in a temperature rising viscosity measurement as described below, in which the thermosetting matrix resin composition is subjected to temperature rising at 2.0°C/minute, the lowermost viscosity is 0.3 Pa·s to 20 Pa·s, and a temperature range in which the lowermost viscosity is exhibited is 100°C to 120°C
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Aprepreg sheet (1) is formed by stacking a plurality of unit layers (10a, 10b). In the unit layers (10a, 10b), prepreg tapes (100), in which a reinforced fiber bundle is impregnated with a thermosetting matrix resin composition, are disposed in rows a plurality of times. One or more of the unit layers (10a, 10b) has a gap (G) between adjacent prepreg tapes (100), and the width thereof is 10% or less of the width of the narrower of the adjacent prepreg tapes (100).