【摘要】 基于Wigner Ville分布的时间 频率分析方法 ,对用有限元方法得到涂层 基底系统中的模拟激光超声信号进行分析 ,得到了在该系统中激光激发的瞬态表面波形的模态和能量分布的特征。只需利用单次测量波形 ,通过群延迟时间估计 ,得到涂层 基底系统中表面波的群速度分布。时间 频率方法计算群速度只要单个位移时间波形 ,相比传统群速度的计算和测量比较简单。更多还原

【Abstract】 Laser induced ultrasonic waves in coating-substrate s ystems are broadband and dispersive,and multiple propagation modes overlap in t ime domain.By using time-frequency analysis based on the Wigner-Ville distribu tion,the characters of modes and energy distribution are obtained after analyzi ng laser ultrasound signals in the coating-substrate system,which are obtained by means of the finite element method.Furthermore,time-frequency method provi des a direct measurement velocity dispersion by delay estimation,whose advantag e is that it only needs a single measured signal.更多还原