金属基复合材料结构是金属层与非金属层多层粘接而成的复合结构,非金属层的应力行为主要体现在粘接面上,利用应力一时延模型测量应力,非金属层的深层反射回波信号非常微弱,给各层信号的识别存在极大的困难,不能准确估计时间延迟。文中从非线性超声理论出发,提出运用非线性超声的二次谐波非线性系数进行非金属层应力检测,实验结果表明非线性系数可以表征应力。
Metal matrix composite structure (MMCS) is a kind of adhesive composite which consists of metal and non-metal layer. The non-metal layer stress behaves on the adhesive layer,when the model of stress and time delay is used to test stress,the echo signal from deep non-metal layer is weak and it is very difficult to recognize the signal of each layer and is unable to estimate time delay precisely. This paper proposed nonlinear ultrasonic coefficient to test non-metal stress. The experimental results show that the nonlinear ultrasonic coefficient can represent the stress of non-metal layer effectively.