Discontinuous Fiber Composite with Cut Angles for Flow and Strength
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Solution Overview
Problem
Conventional fiber-reinforced composite materials face challenges in achieving both high fluidity and mechanical characteristics, particularly in forming complicated shapes with uniformity and minimizing defects like sink marks and warpage.
Innovation Solution
A discontinuous fiber-reinforced composite material with a specific fiber bundle form and varying lengths, where the fiber bundles are cut at predetermined angles to optimize fluidity and mechanical properties, is developed. This material includes a matrix resin and discontinuous reinforcing fibers with a number average fiber length of 3 to 100 mm, and the fiber bundles are cut at angles that satisfy specific acute angle ratios to enhance filling and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If discontinuous reinforcing fibers are used to form complicated shapes, then fluidity is improved, but mechanical characteristics and uniformity deteriorate
Solution Approach 1:
The patent applies parameter changes by controlling the fiber bundle length distribution (number average length 5-50mm with specific standard deviation ratios) and tip angle distribution (number average 10-60 degrees with specific standard deviation ratios). These parameter optimizations enable the discontinuous fibers to achieve both high fluidity for complicated shape formation and maintained mechanical characteristics, resolving the contradiction between ease of operation and strength.
2Ease of operation
If discontinuous reinforcing fibers are used to form complicated shapes, then fluidity is improved, but uniformity deteriorates
Solution Approach 1:
The patent optimizes uniformity by controlling the distribution parameters of fiber bundle lengths and tip angles. Specifically, the number average fiber bundle length is set to 5-50mm with standard deviation ratio of 0.05-0.50, and number average tip angle is set to 10-60 degrees with standard deviation ratio of 0.05-0.50. This statistical control of parameters ensures uniform fiber distribution and orientation during molding, preventing defects while maintaining high fluidity for complicated shapes.
3Productivity
If conventional chopped strands are used, then production efficiency is improved, but uneven distribution and orientation occur causing defects
Solution Approach 1:
The patent improves manufacturing precision while maintaining production efficiency by changing the parameters of fiber bundle characteristics. The number average fiber bundle length (5-50mm) and standard deviation ratio (0.05-0.50), along with number average tip angle (10-60 degrees) and standard deviation ratio (0.05-0.50), are optimized to ensure uniform distribution and orientation. This allows conventional high-speed chopping methods to produce fibers with controlled statistical parameters, achieving both high productivity and manufacturing precision.
4Strength
If continuous fibers are used, then mechanical properties are improved, but formation of complicated shapes becomes difficult
Solution Approach 1:
The patent applies segmentation by dividing continuous fibers into fiber bundles with controlled characteristics. The fiber bundles have number average lengths of 5-50mm with specific standard deviation ratios, and number average tip angles of 10-60 degrees with specific standard deviation ratios. This segmentation maintains sufficient fiber length for mechanical strength while enabling the bundles to flow and conform to complicated three-dimensional shapes, resolving the contradiction between strength and shape complexity.
Data Source
Figure 1(A)~2(C)
Figure 3~4(b)
AI summary
Provided is a discontinuous fiber-reinforced composite material which comprises: discontinuous reinforcing fiber aggregates comprising discontinuous reinforcing fibers having a number average fiber length of 3 to 100 mm; and a matrix resin. The discontinuous fiber-reinforced composite material is characterized in that: the discontinuous reinforcing fiber aggregates include a plurality of discontinuous reinforcing fiber bundles obtained by bundling single yarns of a prescribed number of the discontinuous reinforcing fibers in the same direction; the discontinuous reinforcing fiber bundles have a cut surface which forms a fixed angle with respect to the orientation direction of the single yarns; and the tip angles which form the acute angles of ends of the discontinuous reinforcing fiber bundles when the discontinuous reinforcing fiber bundles are projected on a two-dimensional plane are small to the extent that the discontinuous fiber bundles have a short discontinuous fiber bundle length, i.e. the distance between the two ends in the orientation direction of the single yarns. Accordingly, provided is a fiber-reinforced composite material which is capable of achieving high level flowability during molding and high level mechanical properties that cannot be achieved by a fiber-reinforced composite material comprising conventional reinforcing fibers and a matrix resin, and which is provided with optimal conditions for exhibiting excellent flowability, particularly during flow molding, and mechanical properties having little variation.