Improved energy- absorbing wheels are under development for use on special-purpose vehicles that must traverse rough terrain under conditions (e.g., extreme cold) in which rubber pneumatic tires would fail. The designs of these wheels differ from those of prior non-pneumatic energy-absorbing wheels in ways that result in lighter weights and more effective reduction of stresses generated by ground/wheel contact forces. These wheels could be made of metals and/or composite materials to withstand the expected extreme operating conditions.
The spring rods could be made from any of a variety of materials, depending on the nature of the anticipated loading and the scale of the wheel. (Experiments have shown, for example, that graphite/epoxy spring rods behave in a predictable, repeatable way.) The spring rods would be arranged in a pin/roller beam configuration to load them optimally and prevent the application of thrust loads (that is, loads parallel to the axis of rotation) to the tire. By appropriate sizing of the spring rods and selection of the spring-rod material, the mechanical compliance of the wheel can be tailored over a wide range.
This work was done by Peter Waydo of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Mechanics category. NPO-30378.
This Brief includes a Technical Support Package (TSP).
Energy-Absorbing, Lightweight Wheels
(reference NPO-30378) is currently available for download from the TSP library.
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Overview
This document presents a technical support package from NASA regarding the development of energy-absorbing, lightweight wheels designed for use in planetary exploration and hazardous terrestrial environments. The work was conducted at the Jet Propulsion Laboratory (JPL) under a contract with NASA, highlighting the innovative approach to wheel design that addresses the challenges posed by rough terrains, such as those found on Mars.
The primary focus of the document is on the necessity for non-pneumatic, compliant wheel assemblies. Traditional rubber pneumatic tires are unsuitable for extreme conditions due to issues like thermal degradation, durability, and outgassing. As vehicles increase in size for exploration purposes, it becomes critical for the wheels to effectively absorb inertial forces generated during traversal over uneven surfaces. This is essential to prevent damage to other vehicle components.
The inventor, Peter J. Waydo, emphasizes the novelty of the wheel design, which incorporates non-conventional materials while maintaining the compliance and traction characteristics of conventional tires. The document outlines the improvements over prior art, detailing how the new wheel assembly can enhance vehicle performance in challenging environments.
The technical report includes references to specific commercial products and processes, clarifying that any mention does not imply endorsement by the U.S. Government or JPL. It also includes a disclaimer regarding liability and the use of information contained within the document.
Overall, the document serves as a comprehensive overview of the innovative wheel technology developed for space exploration, showcasing its potential applications in various terrains and its advantages over traditional tire designs. The emphasis on lightweight materials and energy absorption capabilities positions this technology as a significant advancement in the field of planetary exploration, paving the way for future missions that require robust and reliable vehicular systems.
In summary, this technical support package encapsulates the research and development efforts aimed at creating advanced wheel systems that can withstand the rigors of extraterrestrial environments, ensuring the success of future exploration missions.
