In recent decades, with the development of engineering components in the direction of lightweight, high efficiency and high performance, the stress of engineering components has become higher and higher, the service environment has become more and more harsh, and the cases of engineering component failure caused by fatigue have emerged in an endless stream (Fig. 1). Fatigue of engineering components refers to the change in the properties of materials under the repeated action of stress or strain, which often leads to the fracture and failure of materials. According to statistics, about 90% of the failures of engineering components are related to fatigue. It is very important to carry out a "physical examination" of the fatigue reliability of engineering components and carry out long-life design of "prescribe the right medicine" to prevent and reduce the fatigue failure of engineering components, which is very important to help components achieve safe and reliable service.
Fig.1 Fatigue failure related cases: (a) the wreckage of the "Comet";(b) German high-speed rail "ICE 884" accident**. a) At present, in order to evaluate the fatigue reliability of engineering components and various materials, people often test according to the current test standards such as ASTM and GB, and a large number of long-term fatigue tests need to be carried out with a sufficient number of fatigue samples to obtain the stress amplitude-life curve and fatigue limit of the material, which is both time-consuming and consumable fatigue testing method has been used in industry and laboratory for nearly 100 years. However, with the rapid development of high-tech fields such as aerospace, information, energy, biomedical and artificial intelligence, the need to evaluate the fatigue performance of engineering materials and components at low cost and high efficiency, and the fatigue life of in-service components is becoming increasingly urgent. Recently, Zhang Guangping's team from the Shenyang National Research Center for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, based on the previous research on the fatigue behavior of small-scale materials, proposed the concept that the fatigue properties of materials need to be evaluated at high throughput and quickly, designed and established a system that can perform symmetrical bending fatigue loading tests on multiple small and micro samples at the same time (Fig. 2), and carried out high-throughput fatigue tests on several typical engineering materials used in nuclear power, high-speed rail, automobiles and other fields. The experiments were verified by comparison and computational simulations, and the high-throughput testing techniques and methods for the fatigue properties of materials were established. The study was published in the International Journal of Fatigue under the title The High-throughput Bridge to the Rapid Evaluation of Fatigue Reliability of Structural Engineering Materials.
Fig.2. Schematic diagram of a high-throughput symmetrical bending cantilever fatigue testing system.
This technology can not only simulate the fatigue limit lifting method specified in the standard and quickly obtain the fatigue limit of the material, but also obtain the stress amplitude strain-fatigue life curve at one time, and quickly obtain the fatigue data of the material within a week, which takes only 1 4 (Fig. 3a-c) of the aforementioned standard test. At the same time, based on the classical Tanaka-Mura model, the researchers established the fatigue limit of the material obtained by the test technology, and obtained the theoretical model of the conversion factor between the fatigue limits of the standard sample. Researchers also used this technology to evaluate the fatigue properties of some materials, including F316 stainless steel for bolts of nuclear main pumps irradiated by different temperatures, long-term heat exposure and radiation irradiation. This method has certain applicability in engineering, and provides a new strategy for the rapid evaluation of fatigue properties of advanced materials.
Fig. 3 (a) Comparison of fatigue performance of high-throughput methods and standard methods for typical engineering materials(b) Conversion factor as a function of material scale;(c) Comparison of the time required for fatigue limit testing using high-throughput versus standard methods;(d) High-throughput fatigue performance test and verification of F316 steel for nuclear power after service after irradiation and heat exposure.
The establishment of this technology is of great benefit to the development of key fields such as nuclear power, which not only provides a new method of low cost, high efficiency and fast fatigue performance testing of in-service components, but also provides an effective evaluation strategy and new ideas for the fatigue performance evaluation of complex shape components, material surface coatings, corrosion layers and modified layers, weld areas, material structural elements and stress-strain concentration areas and other small areas. At the same time, this high-throughput fatigue performance testing method and evaluation technology is expected to further promote the efficient establishment of the fatigue performance database of material components, and provide a technical basis for the rapid fatigue life of engineering components driven by physical models and data.