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The continuum/discontinuum multiscale analytical system of the interaction between rigid wheel and lunar soil by coupling discrete elements and matrix module was established. The DEM parameter of lunar soil particles was confirmed by the biax-test. The mesoscopic dynamic behaviors of lunar soil simulant subjected to rigid lugged wheel with different structures were simulanted and analysized by the multiscale method. Comparing the simulation results with the soil-bin test results, the multiscale model not only satisfied the computation accuracy, but also had the much higher computation efficiency.

Traffic safety problem becomes increasingly serious as a result of the rapid development of China automobile industry as well as increasing car’s ownership. The occupant road traffic injury data of NASS / CDS database (2005-2010) are systematically explored to statistically analyze injury characteristics and effects of collision velocity and angle for those occupants with lower extremity injury in frontal crash. Results of the present study has significant value on the design of vehicle crashworthiness and occupant restraint system.

The adhesion and the compressibility of the soft soil will vary as the earth gravity changes. In this study, the pressure-sinkage characteristics in low gravity conditions were investigated by three-dimensional Discrete Element Method (DEM). The data of the DEM parameters were obtained by analyzing the pressure-sinkage relationship embedded in laboratory testing data. The pressure-sinkage experiments of the sample soil in different gravities were simulated by using the software PFC3D. Using the Bekker formula, the values of pressure-sinkage parameters were obtained. The results show that, when the earth gravity changes from one sixth of the standard earth gravity to the standard earth gravity, the sinkage exponent increases lineally. The cohesive module of deformation increases along the conic trend. The low gravities have a sensitive affect on the data of the frictional module of deformation, and the data distribute beside a line. The change laws of the pressure-sinkage parameters provide instructions for the optimization design of vehicles working in low gravity field planet.

The influence of vehicle deformation on the risks of head injury for the drivers involved in frontal crashes is studied using real world crash data. There are three types of vehicle damage distribution considered in this paper, namely, wide distribution, moderate offset, and small offset. The adjusted odds ratios (OR) along with 95% confidence intervals (CI) for the head injuries are estimated by logistic regression, controlling for a wide variety of confounders. Results show that occupants' head injuries are highly related to damage distribution. Small offset crash has greatest threat to head injury. Seat belt is effective in all the crash types of concern. This study provides evidences to upgrade existing frontal crash test program and clue to countermeasure development for occupant protection in different crash modes.