A method is proposed for solving inverse flaw detection problems for rods performing longitudinal oscillations. Based on the modeling of the cross-sectional defect as a known function, the main parameters characterizing it, such as the location and volume of the two lowest oscillation frequencies of the free and cantilevered rods, will be approximately determined. Using numerical simulations, it is shown that to satisfactorily determine the properties of a defect, it is sufficient to use several lower frequencies. A method for identifying a defect by one lowest frequency of a free rod is also proposed, provided the known location of the defect is applied, for which it is necessary to determine the characteristics of the oscillation modes. The results of an experimental study are presented.

中文翻译：

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利用特征频率和纵向振荡形状特征识别棒材的截面缺陷

提出了一种解决用于执行纵向振动的杆的反缺陷检测问题的方法。基于横截面缺陷作为已知函数的建模，表征该缺陷的主要参数（例如，自由杆和悬臂杆的两个最低振荡频率的位置和体积）将大致确定。使用数值模拟表明，要令人满意地确定缺陷的性质，使用几个较低的频率就足够了。还提出了一种通过自由杆的一个最低频率来识别缺陷的方法，只要应用了缺陷的已知位置，就必须确定振荡模式的特性。介绍了实验研究的结果。