中文摘要：

试验发现了钢绞线结构中L（0,1）模态导波存在陷频这一固有声学特性,由此提出一种钢绞线拉力检测新方法。为测试钢绞线中导波陷频特性与拉力的关系,研制了一款柔性低频磁致伸缩传感器,可在30~160 k Hz范围内激励/接收L（0,1）模态导波。在直径17.8 mm和15.2 mm的两种7芯钢绞线上进行导波陷频检测试验,结果表明陷频特征频率与拉力的自然对数值呈良好线性关系,陷频旁侧峰值比随拉力增大而线性增加。试验中1 k N的拉力增量（应力增量约3 MPa）引起的声学参数（陷频特征频率和陷频旁侧峰值比）变化可被检测到并较好的符合标定关系方程。在额定工作载荷内,拉力估算相对误差小于1.5%,这表明新方法具有较高的拉力检测精度。同时,依据试验所得结论,给出了钢绞线结构中L（0,1）模态导波陷频中心频率与拉力关系的修正公式。新方法实施过程简洁,具有很好的工程应用前景。

英文摘要：

An innovative method is presented for tensile force measurement based on the notch frequency property which is a inherent character of longitudinal guided wave in strands. To test the relation between notch frequency and tension in different strands, a flexible low frequency transducer is designed, which can excite/receive L（0,1） mode guided wave in a frequency range of 30 k Hz to 160 k Hz. Notch frequency property is tested on two strands with different diameters of 17.8 mm and 15.2 mm respectively, and the characteristic frequency is found to be linear to the Napierian logarithm of tension and the ratio of two side peak of the notch frequency is improved linearly by increasing the tension. The change of acoustic characteristic parameter including the characteristic frequency and the ratio of two side peak caused by 1 k N tension increment corresponding to 3 MPa stress increment can be detected, and the change conform to the calibration relationship equations. Within the rated working load scope, the relative error of tension estimation is less than 1.5%, so that the presented method can be applied for highly precise tensile force measurement. According to the experimental conclusion, a modifier formulas of the center notch frequency of L（0,1） mode guided wave connected with tension in strands is obtained. The innovative method is easy to operate, and therefore it has good prospects for engineering applications.