Designing for Lunar Conditions

When compared to the harshest environments on Earth, the Moon is far less compatible with human life. Due to its weak magnetic field and lack of atmosphere, the surface of the Moon is susceptible to strikes from debris. Average surface temperatures range from 260F in the sunlight to -280F in darkness. The poles experience even deeper cold, reaching -396F to -413F at the Southern and Northern poles, respectively. The coldest environmental temperature recorded on Earth is -144F, located at the highest elevation in Antarctica.

Advanced Materials and Devices, Inc. (AMAD) recently developed a linear spring-damper system that can withstand harsh polar lunar conditions without shrouding. In place of a coil spring, the liquid spring – magnetorheological gel damper (LS-MRGD) prototype represented an overall volume reduction of 26% compared to a traditional spring-damper system. Prototype testing, including performance testing at high and low temperatures, was performed in-house on our MTS system. To mimic the low-temperatures found at the Moons poles, survival testing was performed using a custom-built chamber designed to soak the LS-MRGD in liquid nitrogen for extended periods of time.

To test the effectiveness of the LS-MRGD and its control logic, a single degree-of-freedom quarter-car experimental test setup was designed and built to work with our MTS 852 Damper Test System. The vehicle chassis mass (1/4), single wheel mass, and tire stiffness were duplicated using structural components, solid bearings, and traditional coil springs, respectively, as shown in Figure 1. Two accelerometers were installed on the setup, one attached to the unsprung mass and one on the sprung mass. A major advantage of this test setup is its modular design. The tire stiffness and masses can be adjusted to accommodate new vehicle specs or spring-damper requirements.

Figure 1. Quarter-car model experimental setup mounted to the MTS testing system. The tests were conducted with various payload weights, with completely passive and fully activated LS-MRGD configurations, using the same test profile as the performance tests. The sprung mass peak acceleration values were plotted against operating velocity.

The fail-safe system utilizes a proprietary MRG that can operate in extreme temperatures. AMAD has designed and built systems for space, maritime, and ground applications. For R&D solutions contact us today.