Chamfered Composite Spar Cap Strips for Shear Stress Transfer
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Solution Overview
Problem
Existing spar caps in wind turbine blades face challenges in stress distribution and design optimization due to significant shear stress transfer issues between composite material strips, leading to potential cracks and delamination, which are not adequately addressed by current designs.
Innovation Solution
The implementation of composite material strips with chamfered end regions along both width and thickness, featuring parallel edges, allows for improved shear stress transfer and cost-effective manufacturing through a single cutting step, enabling efficient production of beams and spar caps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional spar cap construction is used, then the structural strength is maintained, but the manufacturing complexity and labor intensity increase due to multiple separate components requiring assembly
Solution Approach 1:
The patent merges multiple separate spar cap components (end blocks, web blocks, and intermediate sections) into a single monolithic integrated spar cap. This eliminates the need for complex assembly operations including drilling, countersinking, and bonding multiple parts, thereby reducing manufacturing complexity while maintaining structural strength through the integrated design that provides continuous load paths.
2Ease of manufacture
If a monolithic spar cap is used, then the manufacturing process is simplified, but achieving precise chamfered surfaces for bonding requires additional machining operations
Solution Approach 1:
The patent incorporates chamfered surfaces directly into the mold cavity design during the initial composite manufacturing process. The mold cavities are pre-configured with the required chamfer geometries, allowing the chamfered bonding surfaces to be formed simultaneously with the spar cap structure itself. This eliminates subsequent machining operations and ensures precise chamfer dimensions are achieved during the primary manufacturing step.
3Reliability
If separate components are assembled, then repairability is improved, but the overall structural reliability decreases due to potential assembly defects
Solution Approach 1:
The integrated monolithic design eliminates bonding interfaces between multiple components, removing potential failure points from assembly defects such as poor bonding, misalignment, or contamination. The continuous fiber reinforcement and unified structure provide superior structural reliability. For repairability, the design incorporates accessible bonding surfaces and standardized geometries that facilitate repair procedures while maintaining the benefits of the integrated structure.
Data Source
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AI summary
The invention relates to a strip (50) for a spar cap (31) of a wind turbine blade (10), wherein the strip (50) is made from a composite material comprising a matrix and a reinforcement, wherein the strip (50) comprises a first end region (51) and a second end region (52) connected to one another in a longitudinal direction (D) of the strip (50) by an intermediate region (53), wherein the intermediate region (53) comprises two mutually opposed longitudinally extending and parallelly disposed intermediate surfaces (54, 55), wherein a thickness (T) of the strip (50) is determinable perpendicular to the two intermediate surfaces (54, 55) and a width (W) of the strip (50) is determinable perpendicular to the longitudinal direction (D) of the strip (50) and perpendicular to the thickness (T) of the strip (50), wherein at least one of the first and the second end regions (51, 52) is a chamfered end region (51, 52), wherein the at least one chamfered end region (51, 52) starting from the intermediate region (53) and extending in the longitudinal direction (D) is simultaneously chamfered along the width (W) and the thickness (T) of the strip (50), wherein the at least one chamfered end region (51, 52) has a first edge (56) at the intermediate region (53) and a second edge (57) at its free end (58), wherein the first edge (56) and the second edge (57) are substantially parallel to one another.