Discontinuous Fiber Composite Structure for Mold Flow and Strength
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Solution Overview
Problem
Existing fiber reinforced composite materials with discontinuous reinforcing fibers face challenges in achieving both high fluidity during molding and good mechanical properties, particularly in producing complex shapes, due to irregular fiber distribution and orientation, leading to variations in mechanical properties and structural defects.
Innovation Solution
A discontinuous fiber reinforced composite material is developed, comprising 20-70 wt% discontinuous reinforcing fibers, with at least one fiber aggregate forming a bow-shaped configuration when projected onto a two-dimensional plane, and specific ratios and angles of the minimum circumscribed rectangle, to enhance fluidity and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discontinuous reinforcing fibers are used to enable complicated shapes, then ease of manufacture is improved, but mechanical properties deteriorate due to irregular fiber distribution and orientation
Solution Approach 1:
The patent applies local quality by creating fiber aggregates with specific spatial distributions and orientations. Instead of random fiber placement, the invention groups fibers into aggregates that are locally concentrated in specific regions, with each aggregate having a defined orientation relative to the molding direction. This local structuring ensures that fiber reinforcement is maximized where needed while maintaining the ability to form complicated shapes.
Solution Approach 2:
The patent applies preliminary action by pre-forming fiber aggregates with specific orientations before the molding process. The fibers are arranged in aggregates with predetermined orientation angles (0°-45° or 45°-90° relative to the molding direction) before injection molding. This preliminary arrangement ensures that when the resin flows and cures, the fibers are already positioned to provide optimal reinforcement, eliminating the need for post-molding adjustment and ensuring consistent mechanical properties.
2Strength
If fiber aggregates are formed to improve mechanical properties, then strength is improved, but fluidity during molding deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the size, concentration, and orientation parameters of fiber aggregates. The aggregate dimensions are kept within specific ranges (length: 1-50 mm, width: 0.1-10 mm) to balance reinforcement effectiveness with fluidity. The fiber content in aggregates is controlled at 1-50 wt%, and orientation angles are limited to 0°-45° or 45°-90° relative to the molding direction. These parameter constraints ensure that aggregates provide sufficient strength while allowing the resin to flow adequately during molding.
3Strength
If continuous fibers are aligned regularly to achieve excellent mechanical properties, then strength is improved, but adaptability to complicated shapes deteriorates
Solution Approach 1:
The patent applies segmentation by dividing continuous fiber bundles into discrete aggregates of controlled size and orientation. Instead of using long continuous fibers that must be perfectly aligned throughout the entire part, the invention creates multiple smaller aggregates (1-50 mm in length) that can be independently oriented. This segmentation allows the fiber structure to adapt to complex geometries while maintaining local reinforcement effectiveness, as each aggregate can be oriented according to the specific stress patterns of different regions.
Data Source
AI summary
A reinforcing-fiber composite material includes not less than 20 wt % but less than 70 wt % of discontinuous reinforcing fibers, and a matrix resin, wherein at least a portion of the discontinuous reinforcing fibers forms a fiber aggregation, and at least one bundle of the fiber aggregation has a surface that, when projected onto a two-dimensional plane, has at least one region where the number of monofilaments constituting the aggregation is reduced, at opposite ends in a longitudinal direction of a minimum circumscribed rectangle of the projected surface, and at portions other than the opposite ends.