Space Shuttle Docking Lever Spreaders Cold Weld Prevention
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Solution Overview
Problem
Existing docking devices for satellites risk cold welding due to high contact pressure between spreading elements and the nozzle neck, leading to permanent connection issues.
Innovation Solution
The docking device employs lever spreaders with inward projections and a recessed central linkage, reducing contact pressure by forming a form-fit connection and using a pressure spring to spread the spreaders apart, ensuring they abut the nozzle inner wall with lower pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the spreading elements are made thin to reduce material usage and improve docking precision, then the manufacturing precision and docking accuracy improve, but the contact pressure increases leading to cold welding
Solution Approach 1:
The patent changes the geometric parameters of the spreading elements by providing outwardly directed curvature at their distal ends, which distributes the contact pressure over a larger surface area of the nozzle neck, thereby reducing the pressure intensity and preventing cold welding while maintaining docking accuracy
Solution Approach 2:
The spreading elements are designed with outwardly directed curvature at their distal ends, creating a spherical or curved contact surface that matches the curvature of the nozzle neck. This curvature increases the contact area and reduces contact pressure, preventing cold welding while maintaining precise docking
2Weight of moving object
If the spreading elements are made thin to reduce weight and improve maneuverability, then the weight of the docking device decreases, but the structural strength decreases leading to potential failure under vibration
Solution Approach 1:
The outwardly directed curvature at the distal ends of the thin spreading elements creates a more favorable stress distribution under vibration loads, preventing stress concentration and reducing the risk of structural failure while maintaining the weight benefits of thin design
3Loss of substance
If the spreading elements are made thin to reduce material consumption, then the loss of substance decreases, but the contact pressure increases causing permanent attachment
Solution Approach 1:
By changing the geometric parameters of the spreading elements to include outwardly directed curvature, the patent reduces contact pressure and prevents cold welding, allowing the thin spreading elements to be reused after docking without permanent attachment to the satellite
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 design significantly reduces the likelihood of cold welding between the spreaders and the nozzle, allowing for reliable and secure docking without permanent attachment.
Implementation Method 1
using a pressure spring to spread the spreaders apart
Implementation Method 2
The central portion of the linkage is formed with a recess into which the inward projections of the lever spreaders engage when the lever spreaders are spread to a defined opening angle
Data Source
AI summary
In a space shuttle with a device for docking to a satellite, especially a communication or navigation satellite, at least two spreading elements in the form of lever spreaders are pivotally disposed at a retaining part of the docking device, which is concentric to a linkage. The lever spreaders have their proximal ends—relative to the space shuttle—provided with inward projections projecting inward towards the linkage, which inward projections engage in a recess formed in the linkage when the lever spreaders, spread apart to a defined opening angle by the cone of the linkage. When the linkage is retracted further, a pressure spring is compressed. At the same time, the lever spreader caught in the recess are retracted so far that the ends of the lever spreaders, spread apart in a defined manner, positively abut the inner wall of the nozzle neck.