薄板涂层结构镍镀层声学特性检测与弹性常数反演表征方法研究

Research on Measurements of Acoustic Characteristics of Nickel-coating Plate and Inversion Method of Elastic Constants

针对表面涂层技术应用中薄板涂层结构材料弹性常数声学表征无损检测方法开展理论和试验研究。基于声学显微镜技术,利用自主研制的宽频线聚焦探头和非常规小尺寸材料超声无损检测系统,进行小步距(20μm)精确散焦测量和大数据量回波信号(601组)数据采集;采用V(f,z)分析方法获取薄板涂层结构材料的试验频散曲线;结合涂层结构材料声波传播特性分析及理论建模结果,改变纵波波速和横波波速获得不同的理论频散曲线,通过理论频散曲线与试验测量结果的曲线拟合,获取涂层材料声波波速,进而反演材料的弹性常数(如泊松比和弹性模量)。多厚度镍镀层试验测量结果与理论值相吻合,表明测量分析方法可行、结果可靠。该研究成果为涂层材料力学性能无损检测和质量评价奠定了基础。

Theoretical model and experimental research is carried out on material elastic constants inversion method of coating plates by acoustic non-destructive test. Taking advantage of the broadband line focus transducer and the precise ultrasonic nondestructive detection system established on our own, obtained the acoustic characterization of thin coating structure. A great amount of data（601 groups） of pulse-echo signals are acquired in an accurate defocusing interval（20 μm）. V（f,z） analytical method is applied on the extraction of measured dispersion curves for coating sheets. Associated with the theoretical analysis of wave propagation of coating materials, a computation model of theoretical dispersion curves is established. Comparing the experimental data with the theoretical curves, the acoustic wave velocities are obtained by curve-fitting method, and finally the inversion of elastic constants, e.g. Young＇s modulus and Poisson＇s ratio, are achieved. The experimental results agree well with the theoretical ones, while it shows that the inversion method is feasible and reliable. This research laid the foundation of non-destructive evaluation of mechanical properties of coating materials.