中文摘要：

研究早期诊断骨疲劳的方法是当前骨质评价方面的研究热点之一.本文对不同弹性模量下长骨中超声导波的传播特性进行了理论分析和仿真研究.首先,通过数值计算得到导波在管状长骨中的理论解析解.然后对管状长骨进行了时域有限差分（FDTD）仿真,并验证了它与理论解析解的一致性,同时得到长骨中不同模式导波群速度、中心频率和衰减与弹性模量的关系.研究结果表明各个导波模式的群速度和中心频率均随弹性模量的增加而增加,而衰减随弹性模量的增加而减小.说明超声导波的传播特性参量可以反映长骨弹性模量的变化,从而为长骨的早期疲劳诊断提供理论依据.

英文摘要：

How to diagnose the bone fatigue damage at early stages is one of the hot research subjects in bone evaluation field. In this study, the propagation characteristics of ultrasonic guide wave in a long bone under different elastic moduli are analyzed using theoretical calculation and simulation methods. First, theoretical solutions of guided wave in a long bone are calculated. Then, a finite difference time-domain （FDTD） numerical method of simulating the propagation of guide wave in a long bone is presented. The simulation results are in good agreement with the theoretical values. And, the relationship between elastic modulus and the propagation characteristics, including group velocity, central frequency and attenuation, is discussed. The results show that group velocity and central frequency increase with the increase of elastic modulus. However, attenuation decreases with the increase of elastic modulus. Those results demonstrate that the propagation of guide wave can reflect the variation of elastic modulus of long bone, which provides a theoretical basis for evaluating the early stages of fatigue damage in long bone.