Crack-Resistant Insert for Wind Turbine Tower Girth Welds
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Solution Overview
Problem
Wind turbine towers experience crack propagation due to flexural stresses from high winds and turbine operation, leading to reduced lifespan and increased maintenance costs, as the continuous metallurgical and mechanical notch around girth welds provides a homogeneous path for fatigue cracks to propagate.
Innovation Solution
A crack-resistant member is introduced, comprising inserts positioned perpendicular to the weld direction and intersecting the girth weld at predetermined locations, which are attached over removed portions of the girth weld and adjacent heat affected zones to prevent crack propagation, and a method of assembling the tower involves circumferentially joining metal rings with girth welds, removing portions at these locations, and attaching inserts to divert fatigue cracks into the base metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If girth welds are used to join tower sections, then the tower structure is formed, but crack propagation occurs at the welds and heat affected zones
Solution Approach 1:
The patent removes portions of the heat affected zone (HAZ) from the girth weld structure. By cutting out and removing the HAZ portions that are prone to crack initiation and propagation, the unreliable regions are extracted from the load-bearing path, preventing crack development while maintaining the overall weld structure.
Solution Approach 2:
The patent applies different properties to different parts of the weld structure. The HAZ portions are selectively removed while the base metal and weld metal are retained. Additionally, inserts with different material properties (higher tensile strength, different elongation characteristics) are placed at specific locations within the weld to provide localized reinforcement and crack resistance where needed.
2Stability of the object's composition
If continuous girth welds are used around the tower perimeter, then structural unity is achieved, but a homogenous crack propagation path is created
Solution Approach 1:
The patent segments the continuous girth weld by removing portions of the HAZ around the tower perimeter. This creates discontinuities in the weld structure that break up the homogenous crack propagation path. The inserts are placed at specific angular positions (e.g., 0°, 90°, 180°, 270°) to segment the weld into distinct zones, preventing cracks from propagating continuously around the entire circumference.
Solution Approach 2:
The inserts act as intermediary elements within the girth weld structure. These inserts with different material properties serve as mediators that alter the stress distribution and crack propagation behavior. The inserts interrupt the continuous metal matrix and provide a different mechanical response to applied loads, preventing the formation of a uniform crack path.
3Force
If high tensile stresses are applied to girth welds during turbine operation, then the tower supports operational loads, but crack initiation and propagation probability increases
Solution Approach 1:
The patent changes the material parameters of the weld structure by introducing inserts with different tensile strength, elongation, and yield strength characteristics. These parameter changes create a more favorable stress distribution under operational loads. The inserts with higher tensile strength and controlled elongation properties help redistribute stresses away from critical HAZ regions, reducing the probability of crack initiation under high tensile stresses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents crack propagation, improves the structural integrity of the tower, and arrests the growth of fatigue cracks, thereby enhancing the reliability and extending the lifespan of the tower while reducing maintenance costs.
Implementation Method 1
The at least one insert prevents crack propagation in the girth weld of the tower
Implementation Method 2
the girth weld creates an adjacent heat affected zone in each of the joined metal rings
Data Source
AI summary
A crack-resistant member for preventing crack propagation, a method of preventing crack propagation, and method of assembly a tower are provided. The crack-resistant member includes at least one insert attached to at least one removed portion at a predetermined location along a girth weld and adjacent a heat affected zone of the tower. The at least one insert is positioned perpendicular to a weld direction and intersecting the girth weld. The at least one insert prevents crack propagation in the girth weld of the tower.