Heated Deformable Wheel Structure for Lunar and Martian Cold
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Solution Overview
Problem
Existing non-pneumatic wheels are not satisfactory for extreme conditions like those on the Moon and Mars, particularly in permanently shadowed regions where temperatures are extremely low, as they fail to maintain mobility and structural integrity.
Innovation Solution
A deformable wheel with a non-pneumatic load-bearing structure, featuring a laminated annular strip with concentric ferrules and interposition layers made of hyperelastic elastomer, along with metal cables and a thermal insulation coating, and heating means to maintain the interposition layers away from their glass transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional non-pneumatic wheels are used, then the wheel structure is simpler and does not require air pressure maintenance, but the wheel cannot maintain mobility on soft ground and lacks shock absorption capabilities
Solution Approach 1:
The wheel is segmented into multiple functional components: a rigid rim structure, flexible interposition layers made of hyperelastic elastomer, and a deformable tread surface. This segmentation allows each component to perform its specific function - the rigid rim provides structural support while the flexible layers enable deformation and shock absorption, resolving the contradiction between structural simplicity and functional reliability
Solution Approach 2:
The wheel employs composite materials combining rigid metallic components (rim, spokes) with flexible hyperelastic elastomer layers. This composite construction enables the wheel to simultaneously maintain structural integrity for load-bearing and exhibit sufficient deformability for soft ground mobility and shock absorption, addressing the contradiction between structural strength and flexibility
2Temperature
If elastomer-based interposition layers are used, then the wheel can deform to match ground surface, but the wheel fails to operate at extremely low temperatures below -150°C due to glass transition
Solution Approach 1:
The patent changes the material parameter by selecting hyperelastic elastomer with glass transition temperature below -150°C, enabling the material to remain flexible and functional at extremely low temperatures. This parameter change allows the wheel to maintain its deformability and shock absorption capabilities in the temperature range of -220°C to -240°C, resolving the contradiction between temperature range and structural integrity
Solution Approach 2:
The patent uses heating means to actively manage the temperature of the elastomer layers, preventing them from reaching their glass transition temperature. This active thermal management ensures the elastomer remains in its flexible state throughout the mission, compensating for the inherent temperature limitations of elastomeric materials
3Ease of operation
If the wheel deforms significantly to pass obstacles and maintain mobility on soft ground, then the contact pressure becomes low and uniform, but the wheel generates heat that approaches the glass transition temperature of the elastomer
Solution Approach 1:
The patent incorporates temperature monitoring and heating control systems that provide feedback on the thermal state of the elastomer layers. When deformation and friction generate heat that approaches the glass transition temperature, the heating system activates to maintain the elastomer above this critical threshold, ensuring continuous flexibility and functionality during operation on soft ground
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 wheel can withstand temperatures of -220°C to -240°C, maintain mobility on soft ground, and ensure structural integrity by deforming to match the ground surface while maintaining constant ferrule length, thus enabling vehicles to operate effectively in extreme conditions.
Implementation Method 1
the laminated strip is covered with at least one thermal insulation coating made of at least one material having a thermal conductivity of less than 0.2 Wm−1K−1
Implementation Method 2
the wheel further comprises means for heating the interposition layers of the laminated strip
Implementation Method 3
interposition layers each composed of a material the Young's modulus of which is 600000 to 1000 times lower than that of the ferrules, for example made of elastomeric material
Data Source
AI summary
Disclosed herein is a deformable wheel with non-pneumatic load bearing intended to equip a vehicle for driving in extreme conditions such as those encountered on the Moon and on Mars, comprising a hub, a laminated strip comprising a plurality of ferrules assembled with the interposition of interposition layers, and a plurality of metal cables connecting the hub to the laminated strip, the laminated strip being covered with at least one thermal insulation coating made of at least one material having a thermal conductivity of less than 0.2 Wm−1K−1, and the wheel further comprising means for heating the interposition layers of the laminated strip.