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For the purpose of adjusting the calculation of the contact pattern of real hypoid gears, the double third-power spline surface is used for fitting tooth surfaces of pinions and gears accurately according to the measurement results of the gear surface. Based on the two-dimension golden section method for increasing the density of gear grid mesh points, the contact analysis algorithm for discrete real gear surface is established to carry out the contact information of real gear surface and adjust parameters of contact patterns, which is applied for adjusting of machining-tool settings conveniently. In the end, a hypoid gear pair of automobile driving axles is used to verify the feasibility and correctness of the proposed algorithm by rolling tests, which shows that the contact pattern by discrete tooth contact analysis is consistent with the real rolling test.

The material properties of the surface layer caused by deep rolling are closely related to the degree of strain hardening. It is of great significance to establish the prediction model of strain distribution to realize the surface strain control and improve the service performance of deep rolling parts. In this study, the analytical models of elastic-plastic strain based on the Hertz contact theory were established by two different methods. The accuracy of the analytical prediction model of elastic-plastic strain was examined by deep rolling simulation. Then, the influence of deep rolling parameters, such as rolling force, the ball diameter, and material on the elastic-plastic strain along the depth was studied and validated by the microhardness profiles along the depth. The results indicate that the analytical model established by the first method is more accurate, and the error between maximum elastic-plastic strain obtained by the first method and finite element (FE) simulation is 12.6%. The elastic-plastic strain along the depth increases with the increasing rolling force and decreases with the increasing ball diameter, and its effective depth increases with the increasing rolling force. The tungsten carbide ball generates more elastic-plastic strain than balls of the other two materials (silicon nitride and steel). In addition, the elastic-plastic strain profiles are in accordance with the change of microhardness along the depth. In a word, the model can be used to predict the strain distribution along the depth induced by deep rolling. [ABSTRACT FROM AUTHOR]

To clarify the effects of deep rolling parameters on residual stress, two-dimensional and three-dimensional finite element models were developed using the Chaboche hardening model. Both two-dimensional and three-dimensional simulation results were compared with experimental results. The three-dimensional model is more accurate, especially the 90° cut-out model. The maximum errors in the longitudinal and circumferential directions of 90° cut-out are 8.9% and 15.6%, respectively. Compared to 20 MPa, a rolling pressure of 38 MPa results in larger and deeper compressive residual stress in both directions, but lower surface residual stress in the circumferential direction. Compared to 30% overlap, 60% overlap produces larger compressive residual stress in the near surface region in the longitudinal direction and deeper residual stress with lower maximum compressive residual stress in the circumferential direction. The friction coefficient only slightly affects residual stress in the circumferential direction; increasing the rolling speed induces higher near surface residual stress in the circumferential direction. Compared to the HG6 tool, the HG8 tool generates decreasing surface residual stresses and deeper residual stress in both directions. Compared to one pass, two passes significantly increase the residual stress in circumferential direction, but only slightly increase the residual stress in the longitudinal direction. [ABSTRACT FROM AUTHOR]

Long noncoding RNAs (lncRNAs) regulate adipogenesis and other processes associated with metabolic tissue development and function. However, little is known about the function and profile of lncRNAs during preadipocyte differentiation in the chicken ( Gallus gallus ). Herein, lncRNA and mRNA expression in preadipocytes at different stages of differentiation were analyzed using RNA sequencing. A total of 1,300,074,528 clean reads and 27,023 novel lncRNAs were obtained from 12 samples. The number of genes (1336 lncRNAs and 1759 mRNAs; 3095 in total) differentially expressed across various stages declined as differentiation progressed. Differentially expressed genes were found to be involved in several pathways related to preadipocyte differentiation that have been extensively studied, including glycerolipid metabolism, and the mammalian target of rapamycin, peroxisome proliferator-activated receptor, and mitogen-activated protein kinase signaling pathways. To our knowledge, some pathways are being reported for the first time, including the propanoate metabolism, fatty acid metabolism, and oxidative phosphorylation pathways. Furthermore, 3095 differentially expressed genes were clustered into eight clusters, and their expression patterns were determined through K-means clustering. Genes involved in the K2 cluster likely play important roles in preadipocyte differentiation. Six stage-specific modules related to A0 (day 0), A2 (day 2), and A6 (day 6) stages were identified, using weighted coexpression network analysis. Nine central, highly connected .genes in stage-specific modules were subsequently identified, including XLOC_068731 , XLOC_022661 , XLOC_045161 , XLOC_070302 , CHD6 , LLGL1 , NEURL1B , KLHL38 , and ACTR6 This study provides a valuable resource for further study of chicken lncRNA and facilitates a better understanding of preadipocyte differentiation in the chicken., (Copyright © 2017 Zhang et al.)