3D DEM analysis of soil excavation test on lunar regolith simulant

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ORIGINAL PAPER

3D DEM analysis of soil excavation test on lunar regolith simulant Banglu Xi1,4 · Mingjing Jiang2 · Liang Cui3 Received: 11 July 2020 / Accepted: 20 October 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract To validate the application of three-dimensional (3D) discrete element method (DEM) on modeling the excavation process, a discrete analogue of lunar regolith simulant is excavated under terrestrial conditions using DEM and the results were compared with the previous experimental data using TJ-1 lunar soil simulant. The soil failure mechanism is first described at different scales, with detailed DEM studies of excavation force, earth pressure, soil heap, void ratio changes, APR (average micro-pure rotation rate) field, particle displacements and velocities. Following these, the effects of cutting depth, cutting angle, blade width on the excavation force and size of the affected zone are analyzed and compared with the experimental data. The results illustrate that a “real-time” affected zone can be identified from the APR field and particle velocities which fluctuate significantly in a similar tendency to the excavation force at the post-peak stage. In contract, a “cumulative” affected zone can be identified from the void ratio and particle displacements, which remain increasing gradually at the post-peak stage and invariable when the excavation displacement is large enough to allow a stable soil heap to form. In addition, the simulation results can capture the effects of cutting depth, cutting angle and blade width, which reveals the validity of the numerical modeling approach and thus further studies on the effects of lunar environments on soil excavation can be carried out using DEM. Keywords  Soil excavation test · Distinct element method · Lunar regolith

1 Introduction Earthmoving equipment plays an important role in the agricultural, construction and mining industries. A good understanding of soil excavation process is necessary for equipment optimization and operation design. Optimization is particularly crucial if the ultimate goal is to design equipment for extraterrestrial operation. In the past few decades, extensive studies have been carried out on soil excavation tests, including analytical, * Mingjing Jiang [email protected] 1



Collage of Civil Engineering, Hefei University of Technology, Hefei 230009, China

2



Department of Civil Engineering, Tianjin University, Tianjin 300072, China

3

Department of Civil and Environmental Engineering, University of Surrey, Guildford GU2 7XH, Surrey, UK

4

Anhui Key Laboratory of Civil Engineering Structures and Materials, Hefei University of Technology, Hefei 230009, China



experimental and numerical studies. Analytical models [1–4], despite their recognized usefulness, are generally established and calibrated based on experimental tests of terrestrial soils on the Earth which are difficult to extrapolate to special soils (e.g., lunar soil with high internal friction angle and low cohesion) and new