Papers by Author: Jun Shen

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Authors: R. Zhou, D. Wang, Jun Shen, J. Sun
Abstract: M3:2 high speed steels with and without carbon addition were prepared by using powder metallurgy at sintering temperature between 1210 and 1280 °C. Densification, microstructure and mechanical properties of M3:2 high speed steels were investigated. Experimental results show that with 0.4wt% carbon addition, full density high speed steels were obtained at temperatures in the range 1240-1260 °C which is 40 °C lower than that of the undoped counterparts, leading to a sintering window expanded by 10 to 20 °C. By the addition of 0.4wt% carbon, the sintered steels show attractive combinations of bend strength and hardness over those of M3:2 steels without carbon addition. The results reveal that the addition of carbon will not only lower the sintering temperature and oxygen content, but also improve the mechanical properties of the sintered steels.
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Authors: Qing Jun Chen, Jiang Lie Liu, Xian Liang Zhou, Jun Shen, Xiao Zhen Hua
Abstract: A series of wedge shape Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) samples were prepared by copper mold suction casting method. The effects of high Co contents on glass forming ability (GFA) and mechanical properties of Fe24+XCo24-X Cr15Mo14C15B6Y2 bulk metallic glasses (BMG) were investigated, respectively. The glass forming ability of bulk amorphous Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) and Fe41Co7Cr15Mo14C15B6Y2 alloys have been researched. Simultaneously, the thermal conductivity parameters of those alloys were tested. The maximum thickness of amorphous region of wedge-shaped samples are dm =7.80 mm for Fe28Co20Cr15Mo14C15B6Y2, dm =7.10 mm for Fe41Co7Cr15Mo14C15B6Y2 and the thermal conductivity are λ=7.11 w.m-1.k-1 and 7.19 w.m-1.k-1, the thermal diffusivity are α=1.875 mm2/s and 1.905 mm2/s for Fe28Co20Cr15Mo14C15B6Y2 and Fe41Co7Cr15Mo14C15B6Y2 BMGs, respectively. The glass forming ability of Fe28Co20Cr15Mo14C15B6Y2 alloy is bigger than that of well known Fe41Co7Cr15Mo14C15B6Y2 alloy. With the change of Co content, the Vickers hardness of Fe24+XCo24-XCr15Mo14C15B6Y2 (x=0,2,4,6,8) change from 1292 to 1322Hv.
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Authors: Jun Shen, M.L. Zhang, D.Y. Hou
Abstract: A new approach for progressive failure and reliability analysis of carbon fiber reinforced polymeric (CFRP) composite pressure vessel with many base random variables is developed in the paper. The elastic constants of CFRP lamina and geometric parameters of the vessel are selected as the base design variables. CFRP lamina specimen and pressure vessel were manufactured and tested in order to obtain statistics of design variables. The limit state function for progressive failure analysis was set up. Then the progressive failure and reliability analysis of the vessel were performed according to the stiffness degradation model based on Monte Carlo simulation procedure using MATLAB. The distributions of failure loads and the probability of failure of the vessel were obtained. The feasibility and accuracy of the proposed method is validated by good agreement between the simulation and experimental results. Further analysis indicates that the lamina tensile strength in the fiber direction and hoop layer thickness of the vessel have significant influence on the probability of failure of composite pressure vessel.
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