Curved Wind Turbine Tower Reinforcement Frame Design
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Solution Overview
Problem
The inclusion of an access door at the base of a metallic wind turbine tower reduces its cross-sectional strength and creates a stress concentration zone, which is exacerbated by the need for a thicker reinforcement frame to secure the door, leading to increased weight and cost.
Innovation Solution
A curved cross-section tower design with a reinforcement frame formed from multiple parts, where each part's mid-plane is parallel to at least one generatrix of the tower, allowing for a more centered joint and reduced thickness, thereby minimizing stress concentration and material usage without compromising structural resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat reinforcement frame is used to secure the access door at the tower base, then the door can be joined to the tower, but the frame thickness must be oversized to ensure adequate structural resistance
Solution Approach 1:
The frame is designed with curvature that conforms to the curved cross-section of the tower, replacing the flat frame design. This curvature allows the frame to efficiently distribute loads around the circular tower section, providing adequate structural resistance with reduced thickness and weight compared to a flat frame design.
Solution Approach 2:
The frame thickness is optimized locally around the orifice zone, providing maximum reinforcement where the stress concentration occurs at the door opening, while maintaining thinner sections in areas where less reinforcement is needed, thereby reducing overall frame weight while ensuring structural integrity.
2Strength
If the frame thickness is increased to compensate for the curvature mismatch, then adequate structural resistance is achieved, but the frame becomes heavier and more expensive
Solution Approach 1:
The frame is designed with curvature that conforms to the curved cross-section of the tower, replacing the flat frame design. This curvature allows the frame to efficiently distribute loads around the circular tower section, providing adequate structural resistance with reduced thickness and weight compared to a flat frame design.
Solution Approach 2:
The frame geometry parameters, particularly the curvature radius and thickness distribution, are optimized to match the tower's cross-sectional profile. This parameter optimization ensures that the frame provides maximum structural efficiency with minimum material usage, reducing both weight and cost.
3Ease of manufacture
If a single flat piece is used to create the frame, then manufacturing is simpler, but the frame does not conform to the tower curvature and requires excessive thickness
Solution Approach 1:
The frame is divided into multiple segments or panels that can be individually formed with the appropriate curvature to match the tower's cross-section. These segments are then assembled and joined together to form the complete circular frame, achieving both geometric conformance and manufacturing feasibility.
Solution Approach 2:
The frame is designed with curvature that conforms to the curved cross-section of the tower, replacing the flat frame design. This curvature allows the frame to efficiently distribute loads around the circular tower section, providing adequate structural resistance with reduced thickness and weight compared to a flat frame design.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
The tower (15) comprises: a wall (11) having an orifice (12) for accessing the interior of the tower (15), and an outer surface defined by generatrices; and a reinforcement frame (13) joined to the tower (15) in the orifice (12) zone, and comprising least two parts (14) joined therebetween. Each part (14) has a midplane (20) that is parallel to at least one generatrix, the mid-planes (20) of at least one pair of adjacent parts (14) forming an angle other than 180° therebetween. It enables the obtention of a frame (13) more conformed to the curvature of the tower (15), combining savings in the material of said frame (13), greater optimisation of the resistance of the tower (15) and reduced stress concentration.