Reinforced Fiber Laminate Sheet for Drapable 3D Composite Forming
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Solution Overview
Problem
Existing methods struggle to produce a reinforced fiber laminate sheet with sufficient drapability and form stability, especially when dealing with complex three-dimensional shapes, leading to issues like wrinkles and delamination, which affect the mechanical properties of the resulting molded body.
Innovation Solution
A reinforced fiber laminate sheet is created by integrating unidirectional fiber bundle layers with different orientations using a fixing element, where the fixing elements are strategically positioned to maintain drapability and form stability without direct binding forces, with specific area and distribution criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prepregs are used for autoclave molding to obtain high reliability and quality aircraft members, then the mechanical properties and reliability are improved, but the manufacturing cost increases due to expensive autoclave equipment
Solution Approach 1:
The patent introduces a film as an intermediary between the fiber bundle layer and the molding die. This film enables the fiber bundles to be stably held and released during the molding process, allowing RTM/VaRTM to achieve reliability comparable to autoclave molding while avoiding the need for expensive autoclave equipment. The film acts as a temporary carrier that facilitates the transition from high-cost autoclave processing to cost-effective RTM/VaRTM processing.
2Ease of manufacture
If dry fabric or preform substrates are used for RTM/VaRTM to reduce manufacturing cost and cycle time, then the ease of manufacture is improved, but the reinforced fibers are not strongly bound together leading to insufficient mechanical properties
Solution Approach 1:
The patent segments the binding function into two parts: (1) the film binds adjacent fiber bundles together during handling and molding to maintain structural integrity, and (2) the matrix resin binds the fiber bundles together after impregnation to provide final mechanical strength. This segmentation allows the use of simple dry fabric substrates for cost-effective manufacturing while ensuring both handling stability and final mechanical properties.
3Adaptability or versatility
If prepregs are deformed with a draping die to obtain complicated three-dimensional shapes, then the adaptability to complex shapes is improved, but wrinkles are generated that adversely affect mechanical properties
Solution Approach 1:
The patent applies preliminary action by pre-binding adjacent fiber bundles together with the film before the molding process. This pre-binding stabilizes the fiber bundle structure, preventing relative displacement and wrinkle formation during subsequent draping operations. The fiber bundles are held in their intended positions beforehand, ensuring manufacturing precision is maintained even when forming complicated three-dimensional shapes.
4Productivity
If ATL machine is used for automatic lamination of prepregs to improve productivity and material yield, then the productivity is improved, but the machine cannot be applied to uneven members or members with complicated three-dimensional shapes
Solution Approach 1:
The patent extracts the lamination function from the ATL machine by using dry fabric substrates that can be manually or automatically laid up without requiring complex automated lamination equipment. The film provides the necessary binding function that would otherwise require ATL machine lamination, enabling simple substrate placement methods to achieve the same result and thus improving adaptability to complex shapes while maintaining productivity.
Data Source
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AI summary
The present invention provides a reinforced fiber sheet exhibiting a stable shape and favorable bulking properties, a method for manufacturing same, and a fiber-reinforced resin molded body. The reinforced fiber sheet according to the present invention comprises a plurality of reinforced fiber bundles that are arranged in one direction, wherein first and second reinforced fiber bundle layers, in which there is no direct binding force between reinforced fiber bundles within a layer, are disposed so as to have mutually distinct fiber orientations, and are integrally formed by being fastened together using fastening elements, satisfying conditions (i) and (ii). (i) Fastening surfaces of the first and second reinforced fiber bundle layers have fastening sections that include at least one fastening element, and an average surface area S1 of 100 mm2. (ii) In the fastening sections, the surface area ratio of the fastening elements to the fastening section is 0.1% to 80%, inclusive.