Radiative Insulation for Thermoelastic Deformation Control

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Solution Overview

Problem

Existing systems, such as telescope mirrors and supporting structures, face significant thermoelastic deformations due to axial temperature gradients, which limit the resolution of images formed by telescopes, especially when exposed to variable external radiation fluxes.

Innovation Solution

The system prevents direct radiative interaction between stiffeners and the emissive structure, allowing the thermal radiation to be absorbed by the rear face of the rigid structure, thereby reducing axial temperature gradients and thermoelastic deformations, and includes a heating/cooling unit and temperature control system to maintain the rigid structure's temperature constant.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If stiffeners are arranged at the rear of the rigid structure to reduce mass with respect to mechanical stress, then the mechanical strength is improved, but axial temperature gradients appear in the stiffeners causing thermoelastic deformations

Engineering Contradiction:
Improvemechanical strengthVSAvoiddimensional stability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

A radiative insulation assembly is introduced as an intermediary layer between the stiffeners and the emissive structure. This insulation layer blocks thermal radiation from reaching the stiffeners, preventing axial temperature gradients while maintaining the mechanical support function of the stiffeners.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The space between the rear face of the rigid structure and the emissive structure is segmented into isolated cells by the stiffeners. The radiative insulation assembly is distributed within these cells, creating multiple isolated thermal zones that prevent heat transfer to the stiffeners while maintaining structural integrity.

Inventive Principle:
Principle #1Segmentation

2Stability of the object's composition

If the number and thickness of stiffeners are increased to reduce thermoelastic deformations, then the dimensional stability is improved, but the mass of the system increases

Engineering Contradiction:
Improvedimensional stabilityVSAvoidsystem mass
Core Design Contradiction:
Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The radiative insulation assembly acts as a mediator that blocks thermal radiation paths to the stiffeners. This allows the use of fewer and thinner stiffeners since they are no longer subjected to axial temperature gradients, thereby reducing system mass while maintaining dimensional stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If a heating and/or cooling unit is provided to control the temperature of the rigid structure, then the average temperature control is improved, but axial temperature gradients in the stiffeners persist causing deformations

Engineering Contradiction:
Improveaverage temperature controlVSAvoiddimensional stability
Core Design Contradiction:
TemperatureVSStability of the object's composition

Solution Approach 1:

The radiative insulation assembly is positioned between the stiffeners and the emissive structure, preventing thermal radiation from heating or cooling the stiffeners. This intermediary layer ensures that even when the emissive structure's temperature is actively controlled, the stiffeners remain thermally isolated and maintain uniform temperature, eliminating axial gradients.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 approach reduces thermoelastic deformations, maintains the average temperature of the rigid structure, and allows for a reduction in the number and thickness of stiffeners, resulting in a lighter system with improved image resolution and stability.

Implementation Method 1

the radiative insulation assembly (3) prevents thermal radiation from the emissive structure from reaching the stiffeners

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 2

heating and/or cooling unit which provides heat to the rear face of the rigid structure or extracted from the latter

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP2175298B1System for stabilising a rigid structure subjected to thermoelastic deformations
Publication Date: 2013.02.20 ASTRIUM SAS
  • EP2175298B1 patent drawingFigure 1a~1b
  • EP2175298B1 patent drawingFigure 2~3a
  • EP2175298B1 patent drawingFigure 3b~3c

AI summary

The system has an emissive screen (10) placed against a posterior face (S2) of a rigid structure (1) such that the structure and the screen are in reciprocal thermal interaction by radiations propagated between the screen and the face. A radiative isolation unit (3) with a thin metal layer is placed between brackets (2) and the structure without masking portions (P2), of the face, located in cells of the brackets relative to that of the screen such that thermal interaction between the brackets and the screen is inhibited without inhibiting the interaction between the structure and the screen.