基于响应曲面法的土壤离散元模型的参数标定研究

Research on parameter calibration of soil discrete element model based on response surface method

为准确地建立土壤的离散元模型,获取土壤离散元仿真中的仿真参数,以真实的土壤直剪切试验,与堆积试验来获取土壤的泊松比、堆积角。以堆积角为响应值,基于响应面优化,标定土壤离散元的相关参数。采用Design Expert软件依次设计Plackett-Burman试验、最陡爬坡试验与Box-Behnken试验得到土壤的最优参数组合。选用堆积角为目标对回归模型进行优化,得到了一组最优解。最终获取土壤的内摩擦角19°,泊松比为0.40,土壤的内聚力9.06,土壤接触模型JKR表面能为3.927 J/m^(2)、土壤—土壤恢复系数为0.332、土壤—土壤静摩擦因数为0.719,实际堆积角试验与最优解仿真堆积角试验相比较结果表明,两者在堆积角角度以及堆积角形态上有较高的相似性。证明了本次仿真标定的可行性,为后续农业机械离散元仿真奠定基础。

In order to establish the soil discrete element model accurately and obtain the simulation parameters in soil discrete element simulation,thePoisson s ratio and stacking angle of soil wereobtained by real soil direct shear test and stacking test.Taking the stacking angle as the response value,the relevant parameters of discrete soil elements were calibrated based on response surface optimization.The Plackett-Burman test,the steepest climbing test,and the Box-Behnken test were designed in turn by using Design Expert software to obtain the optimal combination of soil parameters.The regression model was optimized with the stacking angle as the target,and a set of optimal solutions wereobtained.Finally,the internal friction angle of soil is 19°,Poisson s ratio is 0.40,the cohesion of soil is 9.06,JKR surface energy of soil contact model is 3.927 J/m,soil-soil recovery coefficient is 0.332,and the soil-soil static friction coefficient is 0.719.The comparison between the actual pile-up angle test and the optimal solution simulation pile-up angle test showshigh similarity in pile-up angle and pile-up angle shape.It proves the feasibility of this simulation calibration and lays a foundation for the subsequent discrete element simulation of agricultural machinery.