输尿管结石对管壁及尿液影响的有限元分析

Finite element analysis of effect of ureteral stone on the tube wall and urine

目的探讨输尿管结石对管壁及尿液生物力学特性的影响。方法基于ANSYS Workbench 15.0,通过建立输尿管、尿液及结石相互作用的有限元模型,并引入流体控制方程、动力学方程和运动方程等来描述一个生物蠕动周期内输尿管结石对尿液的流动特性、管壁的生物力学特性的影响。结果输尿管一个蠕动周期内尿液流动特性随着结石尺寸的不同而不断变化,而尿液流的质量流率和压力梯度峰值监测随着结石尺寸增大呈现增加的趋势。输尿管蠕动过程中尿液的流速很小,最大值仅为0.04 m/s,尿液的压力变化对输尿管影响较小。结论在一个蠕动周期内输尿管中尿液生物力学参数随着结石尺寸不同而不断变化,较大尺寸的结石易于产生更高的流速和压力梯度,且在一个蠕动周期结束时有尿液回流产生,回流质量流率随着结石尺寸增加而增大。然而,蠕动过程中输尿管管壁的最大应力、应变数值没有明显变化。

Objective To explore the effect of ureteral calculi on the biomechanical properties of the vessel wall and urine. Methods Based on the ANSYS Workbench 15. 0,a finite element model for the interaction between ureters,urine,and stones was established,and fluid control equations,dynamic equations,and equations of motion were introduced to describe the effect of ureteral stones on urine flow characteristics and biomechanical properties of the wall in a biological peristaltic cycle. Results The urine flow characteristics of a ureter during a peristaltic cycle varied continuously with the size of the stones,and the monitoring of the urine flow mass flow rate and pressure gradient peaks showed an increasing trend with increasing stone size. During ureteral peristalsis the flow velocity of urine was very small,and the maximum was only about 0. 04 m/s,and change of urine pressure had a small effect in ureteral wall. Conclusion The biomechanical parameters of the urine in the ureter during a peristaltic cycle vary continuously with the size of the stones. Larger stones tend to produce higher flow rates and pressure gradients,and there is a return flow of urine at the end of a peristaltic cycle. The reflux mass flow rate increases as the stone size increases. However,there is no significant change in the maximum stress and strain values of the ureteral wall during peristalsis.