Rocket Mounting Joint With Roll Pin and Disc Springs for Thermal Strain
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Solution Overview
Problem
Traditional solutions for mounting rocket components that experience large temperature gradients are complex and expensive, leading to potential failures due to thermally induced stress and strain.
Innovation Solution
A joint system using a coiled roll pin, shaft, and disc springs to compensate for thermal expansion and contraction, featuring a coiled roll pin with a channel and shaft, and disc springs at both ends to absorb axial forces, along with washers and nuts to secure the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mounting solutions are used for components experiencing large temperature gradients, then the structural connection is simple and rigid, but the component reliability deteriorates due to thermally induced stress and strain
Solution Approach 1:
The joint system is divided into multiple functional segments: a rigid mounting bracket for structural attachment, a flexible coupling mechanism with bellows-like structure to accommodate thermal expansion, and a separate sealing system. This segmentation allows each component to perform its specific function optimally while reducing stress concentration.
Solution Approach 2:
The coupling mechanism incorporates materials and structures with variable stiffness parameters that change with temperature. The bellows-like structure provides progressive deformation characteristics, being more compliant at high temperatures when thermal expansion is greater, while maintaining sufficient rigidity at lower temperatures.
2Strength
If rigid mounting structures are used to securely attach components, then the structural strength is high, but the thermal stress concentration increases leading to potential failures
Solution Approach 1:
A flexible coupling mechanism acts as an intermediary element between the rigid mounting bracket and the component. This intermediary absorbs thermal expansion forces through its bellows-like structure, preventing direct stress transmission to the component while maintaining secure attachment. The coupling mechanism serves as a stress-isolating interface.
Solution Approach 2:
The joint system incorporates pre-compressed springs and compliant materials that provide cushioning forces before thermal expansion occurs. This beforehand cushioning absorbs the initial thermal stress waves and prevents shock loading on the component, reducing the risk of thermal fatigue failures.
3Reliability
If complex traditional mounting solutions are implemented to manage thermal stress, then the component reliability improves, but the manufacturing cost and assembly complexity increase
Solution Approach 1:
The mounting bracket is designed with universal features that can accommodate different component types and sizes while incorporating the thermal management functionality. The standardized interface and modular design allow the same bracket design to be used across multiple applications, reducing manufacturing complexity and cost while maintaining reliability.
Solution Approach 2:
The flexible coupling mechanism uses cost-effective materials such as elastomers and simple metal bellows structures that can be manufactured through conventional processes. These components are designed to be replaceable if needed, but their low cost and simple construction make them economically viable for single-use or limited-life applications, reducing overall system cost.
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 joint system effectively manages thermal expansion and contraction, reducing the risk of failure by damping vibratory loads and allowing for easy assembly and replacement, suitable for reusable rockets.
Implementation Method 1
the coiled roll pin is configured to provide a radially outward resilient force to the joint to compensate for radial thermal expansion of the joint
Implementation Method 2
the coiled roll pin is configured to damp out vibratory loads from the rocket body
Implementation Method 3
the one or more first and second disc springs are configured to limit an axially tensile force to the shaft to compensate for axial thermal expansion of the joint
Data Source
AI summary
A joint for mounting a component on a rocket, such as mounting a valve to a rocket body. The joint comprises a coiled roll pin and a shaft. The coiled roll pin comprises a rolled sheet defining an internal channel. The shaft extends through the internal channel and extends out both ends of the coiled roll pin. At each end of the shaft is disposed one or more compressible disc springs. Retaining rings or flat washers may compress the disc springs for axial restraint. The ends of the shaft may include a cover with an outer diameter larger than a joint hole. The joint compensates for vibrational loads, for example due to launch, and for dimensional changes, for example due to temperature gradients between two parts being connected by the joint. Some embodiments include no shaft, with the coiled roll pin axially secured by a cover or cover plate.