火药燃气流冲刷作用下身管镀层初始裂纹受力规律研究

Research on the Law of the Force Sustained by the Initial Cracks of Chromium-Plated Barrels Under the Gas Wash Action

火炮发射时身管内膛受到火药燃气的剧烈冲刷作用,内膛镀层表面初始裂纹在燃气作用下发生损伤与扩展。为了研究燃气对镀层初始裂纹受力规律,建立了火药燃气流与含初始裂纹的镀层身管相互作用的流-固耦合有限元模型,利用达西定律描述燃气流在裂纹缝隙中的流动状态,在合理简化与假设的基础上,研究了不同火药燃气压力大小和裂纹角度对镀层初始裂纹受力的影响规律,计算得到火药燃气冲刷作用下裂纹的应力强度因子、裂纹尖端剪切应力和裂纹撕裂位移。结果表明:火药燃气流压力对裂纹尖端应力强度因子和裂纹撕裂位移影响明显;火药燃气流压力一定时,裂纹角度对裂纹撕裂位移和裂纹尖端剪切应力影响较为显著;随着裂纹角度的增大,裂纹撕裂位移逐渐增大,镀铬层裂纹扩展趋势也逐渐从横向张开扩展变为纵向拉伸扩展。该研究方法能够为身管镀层结构设计和提高身管寿命提供一定的指导。

The bore interface is severely eroded by the gunpowder gas when the gun is fired,the initial cracks on the inner bore surface are damaged and expanded under the action of the gas.In order to study the law of the force exerted by the gas on the initial cracks of the coating,a fluid-solid fully coupled finite element model was established for the interaction between the gunpowder gas flow and the coated barrel with initial cracks,and Darcy′s law was used to describe the flow state of the gas flow in the crack gap.On the basis of certain assumptions and streamlining efforts,the influence of different propellant gas pressures and crack angles on the initial crack stress of the coating were studied and the stress intensity factor,crack tip shear stress and crack tearing displacement of the cracks under the action of propellant gas wash calculated.The research results show that the pressure of the gunpowder gas flow has a significant effect on the stress intensity factor and the crack tearing displacement at the crack tip.When the pressure of the gunpowder gas flow is constant,the crack angle has a significant effect on the crack tearing displacement and the shear stress at the crack tip.With the increase of the crack angle,the tearing displacement of the crack also increases gradually,and the crack propagation trend of the chrome-plated layer gradually changes from lateral expansion to longitudinal extension.The research method in this paper can provide certain guidance for coating structure design and barrel life improvement.