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1 超声无损检测的物理基础 1.1检测用的波形机械振动在弹性介质中的传播称为机械波,声波、超声波都是机械波。振动频率高于20kHz的机械波称为超声波。超声检测中常用的频率是500kHz～20MHz。超声波的分类方法很多,在实际检测中是按质点的振动方向与波的传播方向不同来进行分类,可分为如下四类: 1)纵波介质中质点的振动方向与波的传播方向相同的波称为纵波。固体、液体和气体
1 The physical basis of ultrasonic non-destructive testing 1.1 The waveform used for detection The propagation of mechanical vibration in elastic media is called mechanical wave. Sound wave and ultrasonic wave are all mechanical waves. Mechanical wave vibration frequency higher than 20kHz called ultrasound. Commonly used in ultrasonic testing frequency is 500kHz ~ 20MHz. There are many ways to classify ultrasonic waves. In the actual detection, the vibration direction of particles and the propagation direction of waves are classified into the following four categories: 1) Waves with the same vibration direction as the wave propagation direction in the longitudinal wave medium Known as longitudinal wave. Solid, liquid and gas