Wind Turbine Shear Web Foot Load Distribution

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Solution Overview

Problem

Modern wind turbine blades face increased load concentrations as blade size grows, which existing shear web structures struggle to manage effectively, leading to potential structural weaknesses and adhesive bond line failures.

Innovation Solution

A wind turbine blade shear web design featuring a web foot with converging side walls and internal walls that distribute loads evenly across the adhesive bond line, formed from composite materials with a laminate structure, and optionally filled with filler material, to spread loads and enhance structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a T-shaped web foot structure is used with central upstand, then load transfer from spar caps to web panel is achieved, but load concentration occurs at the centre of adhesive bonding causing bond line failure

Engineering Contradiction:
Improveload transfer capabilityVSAvoidadhesive bond line reliability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The web foot is divided into multiple load-bearing elements: a base with multiple upstands (at least two, preferably three or more) spaced across the base width, and internal walls dividing the web foot interior into chambers. This segmentation distributes the load transfer function across multiple adhesive bond locations rather than concentrating it at a single central point, thereby reducing stress concentration and improving bond line reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the web foot are given different structural properties to optimize local load distribution. The upstands are positioned at specific locations (e.g., at thirds or quarters of the base width) to create localized load transfer paths. The internal walls and chambers provide localized structural support and load distribution throughout the web foot interior, ensuring that adhesive bonding is utilized effectively across the entire base area rather than just at the center.

Inventive Principle:
Principle #3Local quality

2Use of energy by moving object

If blade size increases to capture more energy, then energy capture capability improves, but load concentrations on blade structures increase significantly

Engineering Contradiction:
Improveenergy capture capabilityVSAvoidload concentration on blade structures
Core Design Contradiction:
Use of energy by moving objectVSForce

Solution Approach 1:

The load distribution problem is solved by transitioning from a two-dimensional T-shaped cross-section to a three-dimensional structure with internal walls and chambers extending into the web foot interior. This additional dimension provides multiple load transfer paths and distributes stresses throughout the volume of the web foot rather than concentrating them at the central upstand, enabling the structure to handle the increased loads from larger blades.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP3658767B1Web foot for a shear web
Publication Date: 2022.12.14 VESTAS WIND SYSTEMS AS
  • EP3658767B1 patent drawingFigure 1~2
  • EP3658767B1 patent drawingFigure 3~4
  • EP3658767B1 patent drawingFigure 5

AI summary

A shear web foot for a wind turbine blade is described. The shear web foot extends longitudinally and comprises a base for attaching to an internal surface of the blade and first and second side walls. The side walls extend respectively from opposite longitudinal sides of the base. At least part of each side wall is inclined relative to the base and inclined towards the other side wall. A web-foot interior is defined at least in part by the base and the first and second side walls. One or more internal walls are located in the web-foot interior. The one or more internal walls extend between the base and the first and/or second side walls and are spaced apart from the first and second side walls to define a plurality of chambers within the web-foot interior.