A systematic calibration and validating method for lunar soil DEM model

Calibration and validating are very important to DEM models especially for lunar soil. A review of present lunar soil models, evolutions, calibrations and verifications was executed. The result showed that most scholars used trial-and-error method to calibrate the parameters, but did not sum up a calibration law; in terms of validating, most scholars only focused on the internal friction angle and cohesion, but did not care about the elastic–plastic performance and adaptation. In this study, a systematic method was established instead of single-methods specifically for the calibration and validating of lunar soil DEM models. This is a multi-step method based on triaxial compression test. First, the alterable constitutive law previously proposed by the authors was used, and the influence law of each parameter on the peak stress difference and the position of failure point was analyzed and summed up for calibration. Second, the stress–strain curve was adjusted to coincide highly with Scott's test curve using loose real lunar soil. Third, the internal friction angle and cohesion under both loose and dense conditions were compared with the optimal estimated values to verify the shear strength. Fourth, the elastic–plastic behavior under dense condition was compared with Scott's test result to verify the adaptation of density. Finally, two application simulations were executed to verify the practicability. By referring the systematic method, the purpose of parameter calibration is more explicit, and the validation is more comprehensive.