中文摘要：

为了对钢绞线进行缺陷检测和应力测量,研究了超声导波纵向模态在钢绞线中的传播特性.首先对钢绞线不同钢丝中纵向模态的频散和多模态等特性进行了理论分析.然后在理论指导下,在长15 m且标称直径17.80 mm的7芯钢铰线、单根外围钢丝和中心钢丝中,分别进行了纵向模态的激励接收实验.确定在自由钢绞线中纵向模态主要在外围钢丝中传播.在频段0～400kHz部分频率下,最低阶纵向模态L（0,1）在钢绞线、外围钢丝和中心钢丝中得到的传播速度与理论值较为吻合.

英文摘要：

Propagation characteristics of longitudinal modes of ultrasonic guided waves are investigated theoretically and experimentally for the purpose of defect detection and stress measurement in steel strands. The characteristics, such as dispersion and multi-mode, of longitudinal modes for different kinds of wires in steel strands are analyzed theoretically. In the experiment, longitudinal modes are excited and received in a 15 meter long, 17.80 mm nominal diameter steel strand and its helical wire and center wire in the experiment under the theoretical guidance. When longitudinal modes excited in free steel strands, their main energy propagates in helical wires. At partial frequencies in the frequency range of 0- 400 kHz, experimental propagation velocities of L （0.1 ） mode, the lowest longitudinal mode, in the steel strand and its helical wire and center wire are well agreement with theoretical prediction.