超声手术刀的优化设计

The optimal design of ultrasonic scalpel

为适应微创手术的要求,设计了频率为55.5 kHz的细长结构超声手术刀。采用有限元方法对其进行模态分析和谐振分析,获取振幅大小、应力分布等参数。通过对手术刀刀身结构进行二次优化,使所设计的手术刀在50~60 kHz频段内以纵振模式为主,刀头和刀身应力分布均匀,最大应力由577 MPa降到375 MPa,远小于医用钛合金材质的超声手术刀的最大抗拉强度。为验证有限元分析结果,分别试制结构优化前后的手术刀模型并进行实验。结果表明：结构优化之后的手术刀工作时,应力分布均匀,径向无明显扰度,轴向输出振幅可以满足生物组织切割的要求。

An ultrasonic scalpel with a slender structure in a frequency of 55.5 kHz is designed to meet the requirement of Minimally Invasive Surgery.By analyzing its model and harmonic with the finite element method,the amplitude and stress distributions are obtained.The structure of scalpel is quadratically optimized to make it dominated by the longitudinal vibration between 50 kHz and 60 kHz,the tip and the body of the scalpel are with uniform distribution of stress,its maximum stress drops from 577MPa to 375 MPa,which is much less than the maximum tensile of the scalpel using biomedical titanium alloy material.In order to test the analysis results with finite element method,the scalpel models before and after optimization have been severally made for experiments.The result shows that,after optimization,the scalpel is with uniform distribution of stress,it has no obvious vibration on the radial direction,and the output axial amplitude is great enough to cut biological tissues.