Academic Papers Published by Dr. Yang in International Journal of Fatigue

Recently, Dr. Yang Jie from School of published two papers in internationally top journal: International Journal of Fatigue (IF：5.489). As the first author, he published a paper titled “Numerical modelling of a new FCP model and a correlation of the FCP rate with the constraint”. USST was the first unit. As the first corresponding author, he published a paper titled “A new creep-fatigue crack growth model and a correlation of the creep-fatigue crack growth rate with unified constraint parameter”. USST was the second unit.
Fatigue is one of the important factors that affect life of structures. Statistics show that more than 80% of engineering structural damage is associated with fatigue failure. In early 19th century, draw people’s attention to fatigue. In recent years, due to the rapid development of, fatigue has become increasingly outstanding.
As well as fatigue, crack tip constraint is also an important factor affecting material fracture behavior and structural life. Constraint is the consequence of the specimens and structures geometry, and it can be divided into in-plane constraint and out-of-plane constraint. In-plane constraint is affected by the sizes of the specimens and structures in the crack propagation direction (such as the specimen width), and out-of-plane constraint is affected by the sizes of those in the direction parallel to the crack front (such as the specimen thickness). When the fracture toughness of a high-constraint specimen is used to evaluate the integrity of a low-constraint structure with defects, conservative evaluation results will be obtained, which will lead to unnecessary repair or scrapping of the structure as well as large economic losses. When the same fracture toughness is used to evaluate a structure with a higher constraint, non-conservative results will be obtained for the evaluation, resulting in danger.
Cyclic loading is very common in some rotating structures, during which fatigue and constraint coexist in the equipment, jointly affecting the fracture behaviors of the materials and the life of the structures. Therefore, to achieve structural designs with long life and high reliability, it is needed to apply the latest research results regarding constraint theory to fatigue problems, using them to develop a long-life and high-reliability design method that considers both fatigue and constraint.
On this basis, new fatigue crack growth model and creep-fatigue crack growth model are established for GH4169 alloy, which is common materials used in aeroplane engines. The fatigue and creep-fatigue crack growth behaviors of GH4169 alloy under different constraints were studied using the above models. Based on the unified constraint parameter Ap, the relationships between the constraint and the fatigue and creep-fatigue crack growth rates of GH4169 alloy are established respectively, which clarifies the rule and essence of the fatigue and creep fatigue crack growth rates as the constraint changes. The linear correlations between constraint and fatigue crack growth rate, and between constraint and creep-fatigue crack growth rate have been globally established in the world. It is emphasized that the fatigue and creep-fatigue crack growth rate to a large extent depends on the area surrounded by the equivalent plastic strain contour at the crack tip, rather than the length of the plastic zone It can be a solution to the problem of transplanting the fatigue behavior measured in the laboratory into an actual structure, and ensure the long life and highly reliable operation of the aeroplane engines.
Tu Shandong, Academician of Chinese Academy of Engineering, Professor Valery Shlyannikov, Research Fellow of Russian Academy Sciences and Professor Zhang Xiancheng, East China University of Science and Technology took part in the research. The project was granted by National Natural Science Foundation of China, Shanghai Pujiang Program.