压电光声技术检测非均匀材料热物性的理论研究

Theoretical analysis of thermal performance on inhomogenous materials by piezoelectric photoacoustic technique

利用压电光声技术研究了测量非均匀材料性能的理论和实验方法,通过两种基本的数学变换,得到了非均匀材料和相邻介质的温度场的表达式,进而在非均匀材料的热扩散率按指数规律变化的前提下,得到了非均匀材料温度场的解析表达式。根据压电光声检测理论,得到了非均匀材料的压电信号的解析式,这样即可通过压电光声检测系统,在不同的频率下测得非均匀材料的光声信号,通过最小二乘法的非线性拟合,确定出非均匀材料热扩散率的分布。该方法具有计算量小、实验简单等特点,并给出了有关的理论模拟和实验结果,验证了理论的正确性。

The theoretical and experimental research of detecting inhomogenous materials by piezoelectric photoacous-tic technique have been carried out. The expression of temperature fields in the inhomogenous materials and adjacent media are obtained by two mathematical transforms, the analytical solution of temperature field in inhomogenous materials is given when thermal diffusivity is assumed to be exponentially changed slowly. The piezoelectric signal expression is obtained by piezoelectric detection theory. The piezoelectric signal of inhomogenous materials can be detection at different frequency by piezoelectric photoacoustic detection system. The distribution of thermal diffusivity on inhomogenous materials can be determined by nonlinear fitting. The theoretical and experimental results are in good agreement.