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

Abstract

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 (LCR) 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 LCR wave and the corresponding normalized amplitude difference Adifboth evolve monotonically. The sensitivity of 5 MHz testing frequency is significantly higher than that of 2.25 MHz. A further analysis of LCR wave with RQA presents that the resulting recurrence plot possesses higher sensitivity. The normalized recurrence rate difference RRdif 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.

Keywords

• fatigue damage
• critically refracted longitudinal wave
• recurrence quantification analysis
• nondestructive evaluation