粉碎器管腔内肝脏颗粒堆积流动过程的接触参数

Contact Parameters of Liver Particle Accumulation Flow in the Cavity of a Pulverizer

目的实现肝脏组织颗粒离散元模型接触参数的标定。方法基于MATLAB图像处理技术,测量肝脏组织颗粒的堆积角;采用'Hertz-Mindlin with JKR'接触模型对肝脏组织颗粒进行堆积角的仿真试验,以滚动摩擦系数和JKR表面能作为因素设计正交试验;采用批处理方法标定接触模型的参数,将结果中最优参数组合进行二次仿真标定验证。结果物理试验所得到的堆积角为11.2°±0.86°,正交试验中第6组参数组合得到的堆积角为11.8°,相对误差为5.1%,即物理试验与仿真试验在堆积角度和形状上具有较高的相似性;影响堆积角的因素顺序依次为:组织颗粒与不锈钢板之间JKR表面能>组织颗粒与不锈钢板之间滚动摩擦系数>组织颗粒与组织颗粒之间JKR表面能=组织颗粒与组织颗粒之间滚动摩擦系数。结论可利用该优化参数对生物组织开展进一步的组织颗粒与粉碎器间的离散元仿真,从而揭示组织颗粒在肌瘤粉碎器作用下的流动堆积状态。

Objective To calibrate contact parameters of liver tissue discrete element model.Methods Based on MATLAB image processing technology,the accumulation angle of liver tissues was measured.The’Hertz-Mindlin with JKR’contact model was used to simulate the accumulation angle of liver tissues.The orthogonal experiment was designed with the coefficient of rolling friction and the energy of JKR surface as factors.The parameters of the contact model were calibrated by batch processing,and the optimal parameter combination was verified by secondary simulation calibration.Results The accumulation angle obtained by the physical test was 11.2°±0.86°.In the orthogonal experiment,the accumulation angle of the 6th set of parameter combinations was 11.8°,and the relative error was 5.1%.The simulation test and the physical test had a high similarity in accumulation angle and shape.The sequence of factors affecting the accumulation angle was the JKR surface energy between the tissue particles and the stainless steel plate>the rolling friction coefficient between the tissue particles and the stainless steel plate>the JKR surface energy between the tissue particles and the tissue particles=the rolling friction coefficient between the tissue particles and the tissue particles.Conclusions The optimization parameter could be used to further conduct the discrete element simulation between the tissue particles and the pulverizer,so as to reveal the accumulation and flow state of the tissue particles under the action of myoma pulverizer.