Analysis on rail fatigue damage mechanism based on entropy increment principle in a railgun

摘要：

　　Rail surface damage is common in electromagnetic launch.Even the rail is good in one shoot, there may be appear damages after several shoots.It is considered that mechanical contact stress is one of the factors causing the failure of the rail surface.In this paper, it is found that the thermal stress is a more important factor to the damage.By 3D FEM analysis, first the mechanical contact force gives the pressure stress, and then the thermal stress is changed into tensile stress.As the repeated compression and tension on the rail surface, which may result in fatigue damage.Besides, the more import damage is that the temperature gradient lead to large entropy increment which is larger than the mechanical action.The existence of temperature gradient greatly increases the entropy in the material.When the irreversible entropy increment is accumulated to a certain value, the material will be destroyed.Based on the second law of thermodynamics, the prediction formula of fatigue life is derived by entropy increment principle.From the theoretical point of view, the existence of temperature gradient greatly increases the entropy in the material.Then using the entropy increment principle to product the lifetime.

关键词： Railgun Material life Fatigue Entropy increment Thermal stress

作者: Bo TANG Ying-tao XU Gang WAN Jiang YUE Hai-yuan LI Bao-ming LI

作者单位: National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing

会议类型: 国际会议

会议名称: 2018 International Conference on Defence Technology (2018国际防务技术会议)

会议地点: 北京

会议语种:英文

页码: 132-137

在线出版日期: 2018-10-21（万方平台首次上网日期，不代表论文的发表时间）