轴类镀层结构材料力学性能声学表征方法研究

针对轴类镀层结构材料力学性能无损表征方法开展理论和实验研究,对于表面工程的质量检测与评价具有重要意义。利用自主开发的超声显微测量系统与PVDF线聚焦探头,对不同厚度的轴类镀层材料进行散焦测量。针对轴类试件表面波传播路径与散焦距离的非线性关系,分析了线聚焦探头几何尺寸与散焦距离和试件轴径间的匹配关系,优化检测参数,并在V(f,z)分析法的基础上,采用相位相关分析法获得轴类镀层材料的实验频散曲线。结合镀层材料声波传播特性,采用基于模拟退火的粒子群优化算法(PS-B-SA)将理论频散曲线与实验频散曲线相拟合,反演轴类镀层结构材料的声学参数,进而表征镀层材料的弹性常数。多个不同厚度轴类镀层结构材料弹性常数及镀层厚度的反演结果与实际值相吻合,表明该测量方法可靠、结果准确。该研究成果为轴类镀层结构力学性能无损检测提供了技术手段,也为工程材料表面工程加工性能的评价提供了新方法。

Research on measurements of material mechanical properties of layer coated cylinders with ultrasonic method

Theoretical and experimental researches are carried out on non destructive evaluation of mechanical properties of layer coated cylinders, which is of great significance for the surface quality detection and evaluation. In this work, the lab developed acoustic microscopy and the line focus PVDF transducers are applied in the defocusing measurement with different coating thickness. Considering the nonlinear relationship between the propagation path of the surface wave and the defocusing distance, the geometric parameters of the PVDF transducer are related to the defocusing distance and the cylindrical radius. A correlation analysis method is developed based on V(f,z) analysis to extract the dispersion curves. Combined with the characteristicsof wave propagation of coating materials, the acoustic parameters of cylindrical coating materials are inversed by fitting the theoretical curves to the experimental ones, using the particle swarm optimization based simulated annealing(PSO SA) algorithm. Hence, the elastic constants of coatings are obtained. The experimental results indicate that the measurement results well match the theoretical counterparts, which prove that this method is reliable and accurate. This method provides a powerful technique for the non destructive evaluation of cylindrical coating materials. Furthermore, it can be a great tool for evaluation of material properties in Surface Engineering.