Hole Prestressing Sleeve to Suppress Ovalization Under Load

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Solution Overview

Problem

The presence of holes in components, such as those in wind turbines, leads to structural weakness and potential ovalization under load, necessitating additional stiffening structures which increase weight, cost, and space requirements.

Innovation Solution

A prestressing device comprising a sleeve and tensioning mechanism is inserted into the hole to deform the sleeve radially, exerting a force on the component surface to counteract peak loads and reduce ovalization, thereby prestressing the material around the hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If holes are introduced in components for access or handling purposes, then ease of operation is improved, but structural strength deteriorates due to ovalization under load

Engineering Contradiction:

Improveaccess and handlingVSAvoidstructural strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The prestressing device applies preliminary compressive forces to the material surrounding the hole before the component is subjected to operational loads. This preliminary action creates a pre-compressed state that counteracts the tensile stresses that would otherwise cause ovalization, allowing the hole to maintain its shape and the component to retain its strength.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The prestressing device introduces forces that act in opposition to the harmful ovalization effect before it occurs. By pre-applying compressive stresses around the hole perimeter, the device creates a counteracting force field that resists the tensile stresses induced by external loading, thereby preventing the hole deformation that would compromise structural integrity.

Inventive Principle:

Principle #9Preliminary anti-action

2Strength

If additional stiffening structures are added to compensate for hole-induced weakness, then strength is improved, but weight increases

Engineering Contradiction:

Improvestructural strengthVSAvoidcomponent weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The invention extracts and eliminates the need for additional stiffening structures by using the existing hole geometry and material. The prestressing device utilizes the hole itself as the anchorage point for applying prestressing forces, thereby removing the requirement for separate reinforcement elements and reducing overall component weight while maintaining structural strength.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If additional stiffening structures are added to prevent ovalization, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvehole stabilityVSAvoidcomponent structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The prestressing device merges multiple functions into a single integrated system. The device combines the anchorage function (utilizing the hole), the prestressing function (applying compressive forces), and the reinforcement function (preventing ovalization) into one unified mechanism, thereby improving reliability without increasing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

4Strength

If components are designed with higher strength to compensate for holes, then strength is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecomponent strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The prestressing device changes the stress state parameters in the material surrounding the hole by introducing pre-compressive forces. This parameter change allows the component to be manufactured with standard material properties and geometries, avoiding the need for expensive high-strength materials or complex heat treatment processes while still achieving the required strength and ovalization resistance.

Inventive Principle:

Principle #35Parameter changes

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

This approach extends the component's lifetime by reducing peak loads and ovalization, allowing for lighter, cheaper, and more space-efficient designs without the need for additional support structures.

Implementation Method 1

The tensioning mechanism is designed to deform the sleeve in such a way, that the diameter of the outer surface of the sleeve in the radial direction with respect to the insertion axis and/or longitudinal direction can be increased from a first diameter to a second diameter

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

A prestressing of the material of the component in the area surrounding the hole may be performed in such a way that peak loads that otherwise result in the vicinity of the hole, especially due to an ovalization of the hole, can be at least partially compensated

Methodology Applied

Scientific EffectPrestressing: Compression

Data Source

PatentUS20250257715A1Prestressing device, and a related arrangement, wind turbine, and method

Publication Date: 2025.08.14 SIEMENS GAMESA RENEWABLE ENERGY AS

AI summary

Prestressing device designed to be inserted into a hole in a component to suppress an ovalization of the hole when the component is loaded is provided. The device includes a sleeve and a tensioning mechanism, wherein the device is designed to be inserted into the hole along an insertion axis and the tensioning mechanism is designed to deform the sleeve in such a way, that the diameter of the outer surface of the sleeve in the radial direction with respect to the insertion axis can be increased from a first diameter to a second diameter in at least one axial section of the sleeve.