频率直方图法在复合材料检测中的应用

飞行器中复合材料结构的无损检测大多采用超声波检测方法。在实际检测过程中，类似碳纤维复合材料这样的特殊材料组织的结构比较复杂，所得到的超声波回波信号经常受到较强的结构噪声的干扰，信噪比较低，影响缺陷信号的识别。利用分离谱技术中最小值法，考虑结构噪声幅度对频率变化的敏感性，应用频率统计直方图法，对窄带信号的采样点进行统计、比较，选择绝对值最小的采样点信号作为输出信号，得到最佳频率检测带，对这些频带采用带通滤波器进行滤波，从而较好地将目标回波和结构噪声区分开，更准确地对复合材料构件讲行无损检测。

The Application of Spectral Histogram for Flaw Detection

Because of the excellent performance of the composite material, it is widely used in the manufacture of aircraft. Ultrasonic nondestructive testing is often used to test their damage. Large grained materials are limited by the ability of the detection process to distinguish the flaw signals from the backscattered grain noise in such test. This noise often makes the flaw signal, leading to difficulties in its detection and identification. Use the SSP-minimization algorithm and consider the differences of sensitivity of the frequency between the signals and noise, we can improve the SNR. In this paper, the application of spectral histogram for flaw detection is introduced. Research is presented to demonstrate the performance of the technique.