基于随动边界的火炮身管热力联合效应数值分析

Numeric Analysis of Barrel Heat-pressure Joint Effect Based on Follow-up Boundary

为探索高温高压火药燃气瞬态冲击效应对身管刚度和强度响应的影响,采用有限元方法建立了某大口径火炮身管三维数值模型,并定义了热力载荷边界随弹丸运动而变化的动态过程。通过数值计算得到了首发弹射击条件下身管温度分布演变过程,进一步分析了热冲击载荷、压力载荷以及热力联合效应对身管动态应力响应的影响。计算结果表明:轴向不同位置热冲击载荷的差异性引起轴向非均匀温度分布,使得出现较大的轴向温度梯度,带来显著的轴向温差应力;在温度响应剧烈区域,周向表现为压应力的温差应力与周向表现为拉应力的载荷应力相互叠加,使得内壁质点周向应力分量表现为拉应力与压应力的交替作用,与压力激励作用结果相比,内壁高应力区应力幅值得到一定减弱并随温度响应呈现先下降、后上升的趋势。

In order to explore the transient impact effect of high-temperature and high-pressure propellant gas on the response to barrel strength, the finite element method is utilized to establish a three-dimensional numerical model for a large-caliber gun barrel. The variation of loading boundary of propellant gas with the projectile motion is defined. The evolution process of non-uniform distribution of temperature field in barrel at different moments under the first firing condition was obtained through numeric computation. The influences of thermal load, pressure and the heat-pressure joint effect on the dynamic stress response of barrel are further investigated, respectively. The calculated results show that the difference of thermal shock loads at different axial positions leads to an axial non-uniform temperature distribution, which makes the axial temperature gradient large and causes a significant axial thermal stress. In the area with intense temperature response, the compressive stress induced by thermal load and the tensile stress induced by pressure incircumferential direction make the stress component act as the interaction between the tensile stress and the compressive stress. Compared with the gas pressure effect, the stress amplitude in the high stress region on the inner wall is weakened, and presents a trend of falling first and then rising with the temperature.