Yuanliang Zhang

In our previous work, a parameter a, r, e, a, , Δ, , , , , , , , was proposed to describe fatigue damage caused by micro scratch, whose validity was verified by fracture mechanics. In this article, we summarize an attempt to check the applicability of the a, r, e, a, , Δ, , , , , , , , in the field of the classic S-N curve method. For the sake of objective verification, the experiment data used in this article are from our published work. A high cycle fatigue life model of TC17 based on micro scratches is established with the synthesis of the three-parameter model and Murakami equation modified by a, r, e, a, , Δ, , , , , , , , . Prediction results gave accuracy to mainly fall into the scatter band of factor 2. It can be suggested that a, r, e, a, , Δ, , , , , , , , is suitable for being used in both fracture mechanics and classic S-N curve method. Furthermore, the validity of a, r, e, a, , Δ, , , , , , , , in fatigue behavior analysis combined with current fatigue theories and materials is summarized. The measurement method of scratch depth and width suitable for a, r, e, a, , Δ, , , , , , , , is also introduced.

Prognostics and health management technology (PHM), a measure to ensure the reliability and safety of the operation of industrial machinery, has attracted attention and application adequately. However, how to use the monitored information to evaluate the degradation of rolling bearings is a significant issue for its predictive maintenance and autonomic logistics. This work presents a reliable health prognosis approach to estimate the health indicator (HI) and remaining useful life (RUL) of rolling bearings. Firstly, to accurately capture the degradation process, a novel health index (HI) is constructed based on correlation kurtosis for different iteration periods and a Gaussian process latency variable model (GPLVM). Then, a multiple convolutional long short-term memory (MCLSTM) network is proposed to predict HI values and RUL values. Finally, we perform experimental datasets of rolling bearings, demonstrating that the presented method surpasses other state-of-the-art prognosis approaches. The results also confirm the feasibility of the presented method in industrial machinery.

This paper focuses on the fatigue reliability analysis and the development of a new life model of reliability and crack growth mechanisms in FV520B-I (high strength martensitic-type stainless steels) in the very-high cycle fatigue (VHCF) regime, which haven’t been studied well. First, the fatigue test was carried out to clarify the fatigue failure mechanism in the very-high cycle regime. Based on the test results and fatigue reliability theory, the fatigue life distribution and P-S-N curves were modeled. A new fatigue life evaluation model for FV520B-I is proposed according to the fracture mechanics and classic life evaluation method. With the comprehensive application of P-S-N curves and a new proposed fatigue life evaluation model, a new assumption of a P-Sc-N curve is developed and verified, to quantitatively express the relationship between fatigue life, reliability and fatigue cracking. This is novel and valuable for further fatigue study of FV520B-I.

Remanufacturing notch would be produced after crack polishing in remanufacturing pre-treatment. In the present study, stress concentration of remanufacturing notch was investigated by a series of semi-elliptical notch models using finite element analysis. Comparing with notch width, notch depth has a critical effect on stress concentration. An equation to estimate stress concentration factor (SCF) has been modified to be suitable for remanufacturing notch. Based on the pre-estimation of stress concentration for remanufacturing notch, references on crack polishing plan can be provided in the remanufacturing field.

Different surface roughness type (Ra and Ry) has different effect on the VHCF failure and life. Ra is widely employed as the quantitative expression of the surface roughness, but there are few fatigue failure mechanism analysis and experimental study under surface roughness Ry. The VHCF experiment is conducted out using the specimen with different surface roughness values. The surface roughness Ry is employed as the major research object to investigate the relationship and distribution tendency between the Ry, fatigue life and the distance between internal inclusion and surface, and a new VHCF failure character is proposed.