Expandable Connector Assembly for Lightweight Pretensioned Joints
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Solution Overview
Problem
Existing bolted flange connections in offshore applications, such as connecting wind turbines to monopiles or transition pieces, face challenges with unpredictable preload control, significant material and tool weight, limited scalability, and labor-intensive installation, leading to reduced fatigue resistance and increased maintenance needs.
Innovation Solution
A connector with a fork-shaped cross section and expandable blocks that axially insert and radially expand to create a clamping contact between members, optimizing the cross-sectional area and height ratio of expansion blocks to reduce material usage and weight, while maintaining pre-tensioned connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional bolted flange connections are used, then connection strength is achieved, but weight of bolts and tightening tools increases significantly
Solution Approach 1:
The invention extracts the connection function from traditional bolted flanges and relocates it to a sleeve component that fits into a dedicated channel. The sleeve with radial expansion blocks replaces the need for heavy bolts and complex tightening tools, achieving connection strength through radial expansion and clamping action rather than threaded fastening.
Solution Approach 2:
The invention replaces the mechanical bolt-tightening system with a radial expansion mechanism. Instead of using threaded bolts requiring electrical or hydraulic tightening tools, the system uses radially expandable blocks within a sleeve that create clamping force through a different mechanical principle - expansion against the channel walls to generate holding force.
2Reliability
If bolted flange connections are used, then connection is achieved, but preload control becomes unpredictable and varies significantly
Solution Approach 1:
The invention incorporates sensors that detect the clamping force generated by the radially expanded blocks. This feedback mechanism allows real-time monitoring and verification of the connection force, ensuring predictable and consistent preload control. The system can detect when the desired clamping force is achieved and adjust accordingly, eliminating the unpredictability of traditional bolt tightening.
3Adaptability or versatility
If flanges with bolts are used, then connection is achieved, but scalability is limited for larger wind turbines and greater depths
Solution Approach 1:
The invention creates a universal connection system where the sleeve with radially expandable blocks can be adapted to various sizes and applications. The same basic principle works for different wind turbine sizes and installation depths by simply scaling the sleeve and block dimensions, rather than requiring fundamentally different connection technologies for different applications.
4Strength
If traditional bolted connections are used, then connection is achieved, but material usage and assembly weight increase
Solution Approach 1:
The invention extracts the essential connection function from bulky flange structures and concentrates it in a compact sleeve component. By removing the need for large flanges with multiple bolt holes and the bolts themselves, the design significantly reduces material usage while maintaining connection strength through the radial expansion clamping mechanism.
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 provides a more compact, lightweight, and efficient connection with improved fatigue resistance, reduced material requirements, and easier installation, while maintaining the advantages of previous innovations, such as scalability and reduced sensitivity to preload loss.
Implementation Method 1
one or more than one wedge that is arranged in between the first expansion block and the second expansion block, and that is configured to be displaced longitudinally relative to the channel to thereby radially expand the connector relative to the channel
Implementation Method 2
pushing, in an expanded state of the connector, the first member in a radial direction relative to said channel against the face of the main body of the second member to define a clamping contact
Implementation Method 3
connect the first and second member relative to each other by pushing, in an expanded state of the connector, the first member in a radial direction relative to said channel against the face of the main body of the second member to define a clamping contact and thereby a pre-tensioned connection
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The present invention relates to an assembly, comprising a first member and a second member that are connected via a connector that is axially insertable into a channel defined by passages of the first and the second member, wherein said connector exhibits a length extending in a longitudinal direction of the channel and comprises a first expansion block, a second expansion block, and one or more than one wedge that is arranged in between the first expansion block and the second expansion block, and that is configured to be displaced longitudinally relative to the channel to thereby radially expand the connector relative to the channel, and wherein, at a cross section halfway the length of the connector, a cross sectional area and a height of a first expansion block in a radial direction relative to said channel is smaller than a cross sectional area and a height of a second expansion block in said radial direction relative to said channel. The invention further relates to a method of assembling such an assembly of a first and a second member.