Gradient Coil Casting Compound Crack Prevention
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Solution Overview
Problem
Gradient coils in magnetic resonance tomographs face operational reliability issues due to cracks in the casting compound that can extend into cooling devices, leading to leaks and defects, as the existing materials form strong adhesive bonds under electro-magnetic loads, causing stress transfer and crack propagation.
Innovation Solution
The use of non-adhesive materials for the cooling device and casting compound, such as fluorine-containing plastics or metals, prevents adhesion and creates a microscopic gap, allowing for stress decoupling and preventing crack propagation into the cooling device, while maintaining effective thermal contact through slight expansion and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive materials are used for the cooling device and casting compound, then strong bonding and structural integrity are achieved, but crack propagation into the cooling device occurs under operational loads
Solution Approach 1:
The patent introduces an intermediate layer between the casting compound and the cooling device that prevents direct adhesive bonding. This intermediate layer acts as a stress decoupling interface, allowing the cooling device to be mechanically isolated from cracks in the casting compound while maintaining thermal contact through conductive material properties.
Solution Approach 2:
The patent changes the material parameters of the cooling device by selecting materials with specific thermal conductivity and mechanical properties that prevent adhesion to the casting compound. This parameter change enables the cooling device to maintain thermal efficiency while resisting crack propagation from the casting material.
2Reliability
If non-adhesive materials are used for the cooling device and casting compound, then crack propagation is prevented, but thermal contact efficiency may be reduced
Solution Approach 1:
The patent selects materials for the cooling device with optimized thermal conductivity parameters that compensate for the lack of adhesive bonding. By choosing materials with high thermal conductivity, the system maintains efficient heat transfer from the casting compound to the cooling device despite the non-adhesive interface.
Solution Approach 2:
The intermediate layer is designed with thermal conductive properties that enable it to serve as an effective heat transfer medium between the casting compound and the cooling device. This mediator maintains thermal contact while preventing mechanical adhesion and crack propagation.
3Stability of the object's composition
If strong adhesive bonding is used between cooling device and casting compound, then structural stability is improved, but stress transfer from casting cracks to cooling device increases
Solution Approach 1:
The intermediate layer serves as a stress-isolating intermediary that prevents stress transfer from the casting compound to the cooling device. This mediator maintains structural stability by providing mechanical decoupling while allowing the cooling device to function independently of casting compound cracks.
Solution Approach 2:
The patent segments the structural connection between the casting compound and cooling device by introducing an intermediate layer that creates a deliberate discontinuity in the stress path. This segmentation prevents crack propagation while maintaining functional integration through thermal conduction.
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 enhances long-term operational reliability by preventing crack growth into the cooling device, ensuring no damage and maintaining high heat transfer rates, even under mechanical stress and thermal cycles.
Implementation Method 1
the thermal resistance between the casting compound and the cooling device is as small as possible and a high heat transfer rate is possible
Implementation Method 2
the gap therefore being bridged, owing to the fact that the materials expand slightly or the cooling device is under sufficiently high pressure, owing to the fluid pressure, and expands slightly
Data Source
AI summary
A gradient coil having a coil body made from a cured casting compound and at least one cooler embedded in the casting compound, serving to conduct a fluid coolant, wherein the cooler and the casting compound do not adhere to each other.