Carbon Fiber Stringer Force Distribution in Surfboards
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Solution Overview
Problem
Existing surfboard stringers, typically made of wood or plastic, fail to provide optimal force distribution and flex patterns, limiting the board's speed and strength compared to carbon fiber stringers, while also lacking the aesthetic appeal of wood grain.
Innovation Solution
A tubular carbon fiber stringer is axially aligned and embedded between the longitudinal portions of a surfboard, with vertical and lateral tabs for indexing and tension application, allowing for improved force distribution and shaping, and can be formed in halves or around a mandrel for enhanced structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a carbon fiber stringer is used, then force distribution and board strength are improved, but the board loses the aesthetic appeal and ease of shaping associated with wood grain
Solution Approach 1:
The stringer is divided into multiple longitudinal segments or blocks that can be independently shaped and then joined together. This segmentation allows each piece to be more easily shaped while maintaining the overall strength benefits of a carbon fiber stringer, resolving the contradiction between strength and ease of shaping.
Solution Approach 2:
The patent combines carbon fiber stringer segments with wood grain veneer or decorative layers to create a composite structure. This allows the internal carbon fiber components to provide strength while the external wood-like layer provides aesthetic appeal and can be shaped more easily, simultaneously addressing both concerns.
2Device complexity
If a traditional linear stringer is used, then the board structure is simple, but force distribution is insufficient and flex patterns are poor
Solution Approach 1:
The stringer incorporates curved or arched sections rather than purely linear geometry. These curved configurations optimize the distribution of forces across the board by directing stresses along the natural flow lines of the curve, improving force distribution and flex patterns while adding only moderate structural complexity.
Solution Approach 2:
The stringer design transitions from a simple one-dimensional linear element to a multi-dimensional structure with varying cross-sectional geometries, thicknesses, and orientations. This dimensional complexity enables superior force distribution by engaging multiple structural dimensions to handle different loading conditions.
3Strength
If the board is shaped after joining halves about the stringer, then the stringer provides structural support, but the stringer edge may be visible and wood grain appearance is lost
Solution Approach 1:
The stringer assembly uses composite construction with an internal carbon fiber structural core combined with an external wood grain veneer or laminate layer. This composite approach hides the stringer edge from view while maintaining structural support, as the aesthetic layer conforms to the board shaping process.
Solution Approach 2:
A shaping layer or veneer is introduced as an intermediary between the carbon fiber stringer and the external environment. This intermediary layer serves as a mediator that protects the structural stringer from direct exposure while allowing the board to be shaped, and simultaneously provides the desired wood grain aesthetic appearance.
Data Source
AI summary
One or more tubular carbon fiber stringers are axially aligned with the lengthwise dimension of a water sport board, such as a surfboard. A tubular carbon fiber stringer may have vertical shaping tabs reaching opposed major surfaces of the board and laterally extending tabs that register the stringer position inside of a board by fitting in channels that tightly nest the stringer in the board. Tublar carbon fiber stringers, designed to extend more than half the length of a board, may be made by molding symmetric halves, then joining the halves together, or by winding carbon fiber around a mandrel, epoxying the fiber in place and removing the mandrel. Board blanks have openings to seat the tubular stringers, such as by seating in board halves, or a tubular stringer may be seated in an empty board blank mold with foam blown around the stringer.