【摘要】：離散元法(EDEM)建立土壤模型過程中部分土壤顆粒參數(shù)直接測量難度較大,若基于間接測量的土壤參數(shù)值建立離散元土壤模型進行仿真,導(dǎo)致仿真結(jié)果誤差較大。本文結(jié)合代理模型基本理論,提出一種離散元土壤模型的參數(shù)標定及優(yōu)化方法,步驟如下:根據(jù)基本試驗測定的參數(shù)建立離散元土壤模型;結(jié)合堆積角及剪切試驗,利用模型仿真進行模型參數(shù)敏感性分析;以敏感性參數(shù)為變量,以真實試驗測量值為目標值構(gòu)造代理模型;通過高斯-牛頓迭代法進行參數(shù)優(yōu)化。由敏感性分析結(jié)果知,代理模型自變量為土壤顆粒半徑、顆粒間靜摩擦因數(shù)及滾動摩擦因數(shù),目標量為土壤堆積角、黏聚力、內(nèi)摩擦角。以涿州保護性耕作試驗站土壤(砂壤土)為原型,經(jīng)優(yōu)化建立的土壤模型變量參數(shù)值分別為:顆粒半徑5.7 mm,顆粒間靜摩擦因數(shù)0.45,滾動摩擦因數(shù)0.21。將建立的離散元土壤模型進行輪胎-土壤相互作用仿真模擬,分析輪胎-土壤接觸面最大應(yīng)力、平均應(yīng)力,并通過田間試驗進行驗證,將接觸面最大應(yīng)力值、平均應(yīng)力的仿真值與實際測量值進行比較,結(jié)果表明:虛擬仿真與實測值之間數(shù)值差異在5.1%以內(nèi),標定優(yōu)化后的土壤模型能夠近似代替真實土壤進行仿真。
[Abstract]:In the process of establishing soil model by discrete element method (EDEM), it is difficult to measure some soil particle parameters directly. If the discrete element soil model is established based on indirectly measured soil parameters, the error of simulation results will be large. In this paper, based on the basic theory of agent model, a method of parameter calibration and optimization of discrete element soil model is proposed. The steps are as follows: the discrete element soil model is established according to the parameters measured by basic experiments; Combined with the stacking angle and shear test, the sensitivity analysis of model parameters is carried out by model simulation; the agent model is constructed by taking sensitive parameters as variables and real test measurements as target values; and the parameters are optimized by Gao Si Newton iteration method. According to the results of sensitivity analysis, the independent variables of the agent model are the radius of soil particles, the static friction coefficient and the rolling friction coefficient of the particles, and the target amount is the soil accumulation angle, the cohesion force and the internal friction angle. Using the soil (sandy loam soil) of Zhuozhou Conservation Tillage Station as the prototype, the parameters of the optimized soil model are as follows: static friction coefficient of particle radius 5.7 mm, rolling friction coefficient 0.21. The discrete element soil model is used to simulate the tire soil interaction, and the maximum stress and average stress of the tire soil interface are analyzed, and the maximum stress values of the contact surface are verified by field experiments. The results show that the numerical difference between the simulated and measured values is less than 5.1%, and the calibrated and optimized soil model can approximate replace the real soil for simulation.
【作者單位】： 中國農(nóng)業(yè)大學(xué)工學(xué)院;
【基金】：國家重點研發(fā)計劃項目(2016YFD0700301)
【分類號】：S151.9
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本文編號：2397805