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The fatigue life of the bearing can be predicted effectively by combining the multifield coupling condition of the working process with the internal microstructure. In this paper, a bearing fluid lubrication model is established based on the computational fluid dynamics method, and the calculation result is coupled to the thermal-solid model by the grid mapping method. Through this method, a bearing thermal-fluid-solid multifield coupling dynamics model is established to obtain the evolution information of bearings. Simultaneously, the micro-characterization experiments of SKF6406 bearing (M50 bearing steel) were carried out by electron backscatter diffraction, scanning electron microscope and nano-indentation. The microstructure model of bearing containing micro-inclusions was established by the Voronoi method. On this basis, the microscopic stress distribution characteristics and the motion law of bearing microstructure under the multifield coupling action are solved. In the end, the fatigue life prediction method of rolling bearing was established.

It is of great significance to analyze the influence mechanism of MIG welding parameters during thermo-mechanical coupling to improve the MIG welding process. In this paper, the Python script and t...

It is of great significance to reveal the microevolution mechanism of welded structures during thermo-mechanical coupling to improve the welding quality. In this paper, a random microcrystalline structure model for welds is established by the Voronoi tessellation method. According to the nanoindentation results, heterogeneous grains are produced. A welding workpiece model with statistical significance is established. On this basis, the Python script and the birth and death element method are used to realize the transient growth of a weld, and a thermo-mechanical coupling model for the SUS301L-HT stainless steel metal inert gas welding process is established. The temperature field and thermal stress field are calculated. The calculation shows that the thermal stresses along the growth direction of the weld area are in the form of a “trapezoid,” and the stresses at both ends are small. The stress in the vertical direction of the weld has a single peak, and the peak appears in the center of the weld. The stress distribution of the model that considers heterogeneous grains is obviously inhomogeneous compared with that of the traditional model. The thermal stress distribution in the weldment is obviously inhomogeneous due to the heterogeneous grains, the stresses at the boundaries of the adjacent grains in the weldment change abruptly. It is found that the greater the difference in the mechanical properties between grains is, the more obvious the change.

Laser hardening is an important branch of laser surface hardening technology, which is widely used in metallurgy, transportation, machinery manufacturing, aerospace and other fields. At present, relying entirely on experience or process trial-and-error method, it can not effectively reveal the transient mechanism of laser quenching of disk laser, which is not conducive to shortening the research and development cycle and saving costs. The numerical simulation provides an effective way to obtain the dynamic evolution law of multi-field coupling in laser quenching process. In this paper, a thermo-mechanical coupling model of ASTM 1045 laser quenching process by disk laser is established. In the model, the temperature-dependent physical parameters were calculated by CALPHAD method. The transient law of temperature and microstructural transformation during quenching was obtained by solving the model. The formation and transformation degree of martensite were characterized by the dynamic changes of the depth and width of quenched transformation layer. The quenching structure and transformation hardening law were observed by Axioskop 2 SEM and Zeiss-IGMA HD FE-SEM to verify the accuracy of the simulation results. On this basis, the process parameters of laser quenching were sampled by Monte-Carlo method based on response surface methodology. The sensitivity effects of different process parameters on the temperature field and phase change field of laser quenching were analyzed, which laid a theoretical foundation for the optimization of process parameters. (1) Establish a thermo-mechanical coupling model for quenching process of ASTM 1045, and the sensitivity of the system is calculated. (2) The model can accurately reproduce the transient process of temperature and phase transformation field during laser quenching. (3) The laser power and laser incident angle are positively correlated with the response value. (4) The spot diameter and scanning speed are negatively correlated with response value. (5) The model can effectively calculate the sensitivity of laser quenching, predict the width and depth of quenching layer, and optimize process parameters.

Supplemental material, sj-docx-1-pij-10.1177_13506501211047283 for A method for predicting subsurface fatigue life of rolling bearings based on macro–micro coupling model by Chang Li, Zhengwei Chen, Zhaotai Liu, Xing Han and Xinxue Chen in Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

Supplemental material, sj-docx-1-pij-10.1177_13506501211047283 for A method for predicting subsurface fatigue life of rolling bearings based on macro–micro coupling model by Chang Li, Zhengwei Chen, Zhaotai Liu, Xing Han and Xinxue Chen in Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology

Shrimp hemocyte iridescent virus (SHIV), which was first identified in white leg shrimp (Litopenaeus vannamei) in China in 2014, can cause extensive shrimp mortality and major economic losses in the shrimp farming industry in China. In this study, a novel real-time isothermal recombinase polymerase amplification (RPA) assay was developed using a TwistAmp exo kit for SHIV detection. First, five primers and a probe were designed for the major capsid protein gene (GenBank: KY681039.1) according to the TwistDx manual; next, the optimal primers were selected by a comparison experiment. The primers and probe were specific for SHIV and did not react with shrimp white spot syndrome virus (WSSV), shrimp infectious hypodermal and hematopoietic necrosis virus (IHHNV), shrimp enterocytozoon hepatopenaei (EHP), and macrobrachium rosenbergii nodavirus (MrNV) samples, as well as pathogens of acute hepatopancreatic necrosis disease (AHPND). The RPA assay reached a detection limit of 11 copies per reaction according to probit regression analysis. In addition, RPA assay detected the positive plasmid samples at concentration of 1000 copies/μL within 16.04 ± 0.72 min at a single low operation temperature (39 °C). The results proved that the proposed RPA method was an accurate, sensitive, affordable, and rapid detection tool that can be suitably applied for the diagnosis of SHIV in field conditions and in resource-poor settings.

Obtaining an accurate microscopic representation of the martensitic transformation process is key to realizing the best performance of materials and is of great significance in the field of material design. Due to the martensite phase transformation is rapidly, the current experimental is hard to capture all the information in the Martensite phase transformation process. Combining the phase-field method with the finite-element method, a model of martensitic transformation from a metastable state to a steady state is established. The law of a single martensite nucleus during martensitic transformation is accurately described. By changing the key materials that affect martensite transformation and the phase-field parameters, the effects of the parameters on the single martensitic nucleation process are obtained. This study provides an important theoretical basis for effectively revealing the essence of martensite transformation and can determine effective ways to influence martensite transformation, obtain the optimal parameters and improve the mechanical properties of such materials.