基于临界折射纵波递归定量分析的纯铁疲劳损伤无损评价

Nondestructive evaluation on fatigue damage of pure iron based on critically refracted longitudinal wave combined with recurrence quantification analysis

利用超声检测技术无损评价金属材料的疲劳损伤程度,是保证高性能零部件承载性能和服役可靠性的重要手段。以工业纯铁低周疲劳损伤为研究对象,提出将临界折射纵波(critically refracted longitudinal,L_(CR))与递归定量分析相结合的无损评价方法。结果表明:拉-压加载过程中表现为循环硬化,随加载周次增加至1000周次,L_(CR)波幅值及对应归一化幅值差A_(dif)整体呈单调变化,5 MHz检测频率的灵敏度高于2.25 MHz。进一步对L_(CR)波进行递归定量分析,递归图随疲劳损伤发展变化明显,提取归一化递归度差RR_(dif)作为损伤指标,较时域、频域和时频域最大幅值等指标的灵敏度显著提升,增加幅度最大可达44%,为早期疲劳损伤的无损评价提供了新手段。

Nondestructive evaluation on fatigue damage of metallic materials with ultrasound is important to ensure the load-bearing capability and in-service reliability of high-performance components.The fatigue damage of industrial pure iron was studied,and a nondestructive testing method which combined the critically refracted longitudinal(L_(CR)) wave and recurrence quantification analysis(RQA)was proposed.Results show that with the increasing loading cycles and hardening during the tensile-compressive cyclic loading until 1000 cycles,the amplitude of L_(CR)wave and the corresponding normalized amplitude difference A_(dif) both evolve monotonically.The sensitivity of 5 MHz testing frequency is significantly higher than that of 2.25 MHz.A further analysis of L_(CR) wave with RQA presents that the resulting recurrence plot possesses higher sensitivity.The normalized recurrence rate difference RR_(dif) is extracted.The sensitivity indicates an obvious increase up to 44%compared with the maximum amplitude indexes in time domain,frequency domain,and time-frequency domain.It proves that the proposed method would be a new solution to the nondestructive evaluation on early-stage fatigue damage of metallic materials.