电磁轨道发射中内弹道动力响应特性分析

Analysis of dynamic response characteristics of interior ballistics process in electromagnetic rail launcher

将轨道简化为移动载荷作用下固定在弹性支撑上的Bernoulli-Euler梁,通过静态电磁-结构耦合有限元模型求得外围封装的等效刚度,计算得到发射器的临界速度.另外,利用混合有限元/边界元法建立电磁-结构-运动多物理场耦合的动力学模型,求得枢轨动态接触压力和轨道的应力应变分布特性.通过在轨道背面布置光纤光栅应变传感器,利用测量数据验证了动力响应特性,并分析了弹丸在内弹道的稳定性.针对典型30 mm×30 mm矩形口径发射器,分析及试验结果表明:C型电枢对轨道的电磁挤压力在平顶沿起始时刻达到最大值,之后随着时间推移逐渐减小;电枢通过引起的应力波在高速段容易与轨道中反射应力波发生共振,并且轨道在电枢运动的中间高速段区域受力最为集中,应力集中水平约是起始低速段区域的2.44倍;电枢运动高速段会出现晃动现象,进而引起上下轨道受力的不对称性.分析及试验结果对研究电磁轨道发射器内弹道动力响应特性和发射器结构设计具有重要指导意义.

By simplifying the rail as a Bernoulli-Euler beam fixed on the elastic support under moving loads and obtaining the equivalent stiffness of the elastic support through the finite element model,the critical velocity of the launcher was derived.Dynamic contact force between the armature and the rail and the distribution of stresses and strains were obtained from electromagnetic-structural-motion multi-physics field coupling dynamic model by using hybrid finite-element/boundary-element method.The measuring data of fiber Bragg grating strain sensors on the back of rails were used to verify the dynamic response and analyze armature stability.For the typical 30 mm × 30 mm rectangular caliber launcher,analysis and test results show that the electromagnetic extrusion force of the C-type armature on the rail reaches the peak value at the beginning of the flat-top and gradually decreases as time goes on;the stress waves caused by armature passing are easily resonant with the reflected stress waves in the rail in the high-speed stage,in which the stress exerted on the rail is the most severe and the stress concentration level is about 2.44 times that in the initial region;when the armature operates in the high-speed region,there will be a vibrating phenomenon which will lead the asymmetry of loads on the upper and lower rails.These results have guiding significance for analyzing dynamic response characteristics of internal ballistic process and design launcher.