不同特征下激光超声温度测量研究

Research on laser ultrasonic temperature measurement under different characteristics

为解决金属材料在高温工作环境下进行温度检测时需接触,受限多等问题,使用激光超声技术实现超声非接触式收发,通过对纵波、表面波信号与温度的相关性分析,实现高温工作状态下金属零部件温度的检测。建立20~520℃范围内铝块的激光超声温度检测模型,研究了激光激发的超声纵波、表面波波速与温度的相关性;提出Wigner-Ville分布下激光超声能量谱密度最大点的频率移动特征分析方法,研究了激光超声表面波频率与温度的相关性。研究表明:激光超声纵波、表面波波速及频率随温度升高成线性降低关系,且表面波波速-温度关系对温度检测的灵敏度更高。在单位长度1 cm范围内,表面波声时随温度变化率为1.4×10^(-9) s·℃^(-1),波速随温度变化率为-0.85 m·s^(-1)·℃^(-1),可以分辨1℃的温度变化,为后续的激光超声温度检测研究提供了依据。

In order to solve the problem that metal materials require contact and are subject to many restrictions when temperature detection under high temperature working environment,laser ultrasonic technology is used to achieve ultrasonic non-contact transceiver.By analyzing the correlation between L wave,S wave signals and temperature,temperature detection of metal parts under high temperature working state is realized.The laser ultrasonic temperature measurement model of aluminum block in the range of 20~520℃is established,and the correlation between laser induced ultrasonic L wave,S wave velocity and temperature is studied.A method is proposed to analyze the frequency movement characteristics of the maximum point of laser ultrasonic energy spectrum density under Wigner-Ville distribution and the correlation between the frequencies of laser ultrasonic S wave and temperature is studied.The results show that the L wave,S wave velocity and frequency decrease linearly with the increase of temperature and the relationship between S wave velocity and temperature is more sensitive to temperature detection.In the range of 1cm per unit length,the change rate of S wave acoustic time with temperature is 1.4×10^(-9) s·℃^(-1),and the change rate of wave velocity with temperature is-0.85 m·s^(-1)·℃^(-1),which can distinguish the temperature change of 1℃,providing a basis for the subsequent research of laser ultrasonic temperature detection.