Shock-survivable dewar
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Solution Overview
Problem
Dewars used for storing cryogenic materials are prone to failure due to brittle necks breaking under shock loads during handling, leading to loss of vacuum and damage to valuable contents, with existing add-on indicators only providing visual feedback for orientation and not preventing damage from excessive acceleration or deceleration.
Innovation Solution
A dewar design featuring an outer vessel upper head with a central region that permanently deforms instead of breaking, absorbing shock energy and preserving the vacuum, while the neck remains intact, and visible deformation indicates excessive loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the dewar neck is made from low-conductivity materials to minimize heat leak, then thermal insulation is improved, but the neck becomes brittle and fails under shock loads
Solution Approach 1:
The patent introduces a shock-absorbing element positioned between the neck and the closure member to cushion shock loads before they reach the brittle neck. This element deformable under excessive shock, absorbing the impact energy and preventing neck failure while allowing the neck to remain thin and low-conductivity for thermal insulation.
Solution Approach 2:
The shock-absorbing element serves as an intermediary component between the neck and the closure member. It mediates the transmission of shock forces, protecting the brittle neck from direct shock loads while maintaining the thermal insulation properties of the neck material.
2Loss of energy
If the neck is made thin to minimize conductive heat leak, then thermal insulation is improved, but the neck becomes more susceptible to breaking under shock
Solution Approach 1:
The shock-absorbing element is positioned to cushion shock loads before they reach the thin neck, allowing the neck to be made thin for minimal conductive heat leak while the shock element provides the necessary shock resistance.
3Reliability
If the dewar is designed to be robust to prevent shock failure, then reliability is improved, but visible indication of excessive loading is lost
Solution Approach 1:
The shock-absorbing element includes a visible indicator that changes appearance when deformed by excessive shock loads. This allows the dewar to be robust against shock while providing visible indication when shock limits are exceeded, solving the detection problem.
Solution Approach 2:
The visible indicator on the shock-absorbing element provides feedback about shock exposure. When the indicator shows deformation, it signals that excessive shock has occurred, allowing users to detect and respond to shock events even though the dewar is designed to withstand normal shock loads.
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 dewar design enhances the durability of cryogenic fluid containers by preventing vacuum loss and providing visible indicators of excessive shock, ensuring the safety and integrity of stored materials during handling and transport.
Implementation Method 1
The space between the vessels is evacuated to eliminate convective and conductive heat transport
Implementation Method 2
an insulation space defined between the inner and outer vessels, the insulation space evacuated of air
Data Source
AI summary
A dewar for storing a cryogenic fluid features an inner vessel configured to store the cryogenic fluid and an outer vessel having an outer upper head and an outer lower head. The outer upper and lower heads are joined so as to define an interior chamber of the dewar. The inner vessel is positioned within the interior chamber of the outer vessel so that an insulation space, which is evacuated of air, is defined between the inner and outer vessels. A neck extends between the inner vessel and a central region of the outer upper head. The outer upper head and neck are configured so that the central region permanently deforms without breaking the neck when excessive shock loads are applied to the dewar.