【作者】 田祖安；

【导师】 陈景秋；

【作者基本信息】 重庆大学 ， 流体力学， 2007， 硕士

【摘要】 体外冲击波碎石技术(Extracorporeal shock wave lithotripsy)是20世纪人体结石去除技术的革命性进展,因其无创伤的非侵入式疗法能够大大减轻病人的痛苦而被誉为与MRI,CT并列的三大医疗技术之一。本文首先回顾了ESWL技术的发展及现状,简单说明了该技术中存在的目前尚未明确的问题,着重论述了人体结石受冲击波直接作用导致破坏的机理。为了能够明确冲击脉冲在结石中的传播情况并对此进行数值模拟,本文之后介绍了用于弹性波计算的特征线方法及差分法的基本理论,构造了基于特征线算法的显式差分格式。在此基础上,利用FORTRAN 95编制计算程序,对三种不同材料的一维弹性固体中的弹性波传播进行了数值模拟,并利用Origin pro7.5后处理软件对计算结果进行了可视化处理。数值计算结果表明,特征线法能够很好的计算模拟冲击脉冲或阶跃载荷在一维弹性固体中的传播。对于末端固定位移边界条件及应力自由位移边界的两种情形下的数值模拟结果显示弹性波在结石末端的反相与同相反射非常明显。对于这部分,ESWL中常用的正压峰值为30MPa左右,负压峰值10MPa左右的冲击脉冲在结石末端反射之后叠加的拉应力可达到很高的数值,这样不断的作用足以使结石碎裂。更多还原

【Abstract】 ESWL(Extracorporeal shock wave lithotripsy),which is highly praised as one of the three most important medical treatment technologies as MRI ,CT。Developed over twenty years ago,ESWL is a innovation revolution for kidney stone removal.It’s non-invasive treatment method can greatly lighten the pain of the patients.The paper review the development and status of ESWL at first,also it simply explains many problems which are not definite in this field.The focus are all on the fracture mechanism of kidney stones with shock wave’s direct impact.In order to definite the propagation of shock waves in the kidney stones,the paper introduce the fundmental theory of Characteristic Curve Method and Finite Difference Method. The author then constructs the Explicit Difference Scheme based on Characteristic Curve Method.Programming with Fortran95,the author solve the algebraic equations and obtains the numerical solutions of propagation of elastic waves.In this work the author simulates the propagation of 1-dimension elastic waves in three materials with different boundary conditions.The numerical results are dealt with Origin pro7.5.The numerical values appear that that Characteristic Curve Method is able to perfectly simulate the propagation of elastic waves with step load on the boundary of the solid materials.All the analysis demonstrate that the tensile stress due to the reflection of the pulse with a step compressive front with pressure of the order of 30MPa decaying to a negative pressure of 10MPa at the end of the stone is go up to a higher value,with continuous impact which is enough to destroy the stones in human body.更多还原