Composite Structural Member Wrinkle Prevention
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Solution Overview
Problem
The existing methods for producing composite structural members, such as aircraft wings, face challenges in preventing wrinkles and ensuring strength when using prepreg sheets with narrow fiber directions, particularly in three-dimensionally curved sections, due to the need for slits that divide fibers and increase cut lines, making manual or machine-based bonding cumbersome and inefficient.
Innovation Solution
The method involves bonding narrower prepreg sheets along curved ridges and valleys without additional cut lines, allowing for adjustable lengths to match curvature radii, and using wider sheets on adjacent surfaces to prevent wrinkles and maintain structural integrity, eliminating the need for slits and reducing manual effort in production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If slits are provided in the prepreg sheet to prevent wrinkles in curved sections, then wrinkle prevention is improved, but the fiber is divided and strength is degraded
Solution Approach 1:
The prepreg sheet is segmented into multiple narrow strips along the fiber direction. These strips are arranged and bonded such that their edges align with the ridge, preventing wrinkle formation without requiring slits that would divide continuous fibers. The segmentation occurs in the arrangement rather than in cutting through the fibers.
Solution Approach 2:
Different regions of the composite structure use different prepreg sheet configurations. In curved ridge sections, narrow strips are used to prevent wrinkles. In flat or less curved sections, wider sheets are used to maintain strength. This local adaptation optimizes both wrinkle prevention and structural integrity.
2Adaptability or versatility
If slits are provided in the prepreg sheet to accommodate curvature, then adaptability to curved shapes is improved, but manufacturing complexity increases due to manual slit placement
Solution Approach 1:
The prepreg sheet is pre-cut into narrow strips of predetermined width before bonding. This preliminary action allows the strips to be easily arranged and bonded along curved ridges without requiring complex on-site slit placement or specialized equipment during the bonding process.
Solution Approach 2:
Instead of providing slits in a continuous sheet to accommodate curvature, the invention inverts the approach by using multiple narrow strips whose edges naturally accommodate the curvature. The strips are arranged to match the curvature profile, eliminating the need for slits and their associated manufacturing complexity.
3Object-affected harmful factors
If narrow prepreg sheets are used along ridges to prevent wrinkles, then wrinkle prevention is improved, but the number of bonding operations increases
Solution Approach 1:
Multiple narrow strips are arranged and bonded simultaneously in a single bonding operation. The strips are positioned side-by-side along the ridge, and their edges are bonded together with the adjacent wide sheet in one continuous process, merging multiple bonding actions into a single efficient operation.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
An object of the invention is to provide a method for producing a structural member and the structural member, in which the structural member including a composite material can efficiently be produced such that strength of the structural member is sufficiently ensured while generation of a wrinkle in a composite material sheet is prevented even in a three-dimensionally curved portion of the structural member. A narrow prepreg sheet 20N is bonded along a ridge C, and wide prepreg sheet 20W is bonded to other portions, whereby the wide prepreg sheet 20W having no cut line is bonded to both side portions of the ridge C. In a portion in which a spar 10 is curved, the narrow prepreg sheet 20N is bonded in an axial direction of the spar 10 while divided into plural pieces, and a length of the narrow prepreg sheet 20N is adjusted according to a radius of curvature of the curved portion in the axial direction of the spar 10, whereby various radii of curvature are easily dealt with.