Dewar Vessel Shock-Absorbing Head Design to Prevent Neck Failure
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Solution Overview
Problem
Dewars used for cryogenic material storage and transport are prone to neck failure due to shock and handling stresses, leading to loss of vacuum and damage to temperature-sensitive contents, with existing add-on indicators only detecting orientation and not excessive accelerations or decelerations.
Innovation Solution
A dewar design featuring a fully hydraulic press-formed outer upper head with a shallow dish-shaped central region that absorbs energy and induces permanent deformation under excessive loads, preserving the neck and providing visible indication of shock, while maintaining vacuum integrity.
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 susceptible to shock-induced failure
Solution Approach 1:
The patent designs the outer upper head with a shallow dish-shaped central region that acts as a shock-absorbing element. This region is positioned to receive and attenuate shock loads before they reach the brittle neck, effectively cushioning the neck against impact forces that would otherwise cause failure.
2Strength
If the outer upper head is made rigid to maintain structural integrity, then strength is improved, but shock loads are transmitted directly to the neck causing failure
Solution Approach 1:
The outer upper head is designed with non-uniform local properties: the central region has a shallow dish shape with reduced stiffness to absorb shocks, while the peripheral region maintains sufficient rigidity for structural support. This local differentiation allows the head to simultaneously provide strength and shock protection.
3Measurement precision
If add-on shock indicators are used to detect excessive accelerations, then measurement capability is improved, but they do not prevent product damage from shock
Solution Approach 1:
The patent combines the shock indication function with the structural head component itself. The shallow dish-shaped central region serves dual purposes: it absorbs shock loads to protect the neck, and simultaneously provides visible deformation indication when shock exceeds design thresholds, merging protection and measurement into a single integrated element.
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 shock resistance, prevents vacuum loss, and provides visible signs of excessive loading, ensuring the safety and protection of stored materials by absorbing and indicating high shock loads without neck failure.
Implementation Method 1
a shallow dish-shaped central region that absorbs energy and induces permanent deformation under excessive loads
Implementation Method 2
They are necessarily constructed with minimal thermal connections, including an evacuated space, between an outer vessel and inner vessel that contains the cryogenic materials
Implementation Method 3
The space between the vessels is evacuated to eliminate convective and conductive heat transport
Data Source
Figure 1
Figure 2A~2B
Figure 3
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.