小口径引信磁流变脂解除保险机构设计与延时特性

针对现代小口径炮弹引信作用性能要求高与体积小的矛盾，提出一种新型小口径引信延期解除保险机构。该机构利用智能材料磁流变脂在有/无磁场作用下的开关特性，基于黏弹性液体受挤压采用收缩孔泄流的工作原理，实现引信延期解除保险功能。通过流体动力学和磁场分析，推导出反映机构结构尺寸和流体黏度特性等因素的延期时间数学模型。仿真和试验结果表明：局部阻尼系数经修正后可有效降低模型计算误差，最大误差为6.7%；通过匹配不同泄流孔径、弹丸转速和颗粒体积比等参数，可实现机构延期时间可控范围为9~84 ms. 磁流变脂温度工作范围广且颗粒不易发生沉降，解除保险机构简单可靠，在中、小口径引信中具有潜在应用价值。

Design of a Small-caliber Fuze Magnetorheological Grease Safety and Arming Device and Its Delay Time Characteristic

A novel small-caliber safety and arming (S&A) device is proposed to improve the fuze performance of modern small caliber projectile within a limited space, for which the “locking” and “unlocking” properties of magnetorheological (MR) grease with/without the presence of magnetic field are used. Based on the principle of MR grease flow through an abrupt contraction-expansion under squeezed pressure, the delay time for arming the firing section was obtained. The delay time mathematical model of reflecting the factors, such as structure size and fluid elasto-viscosity characteristics, is further derived by analyzing the fluid dynamic and magnetic fields. Simulated and experimental results show that the modified local damping coefficient favors to reduce the maximum model error to 6.7%. A delay time range of 9-84 ms was successfully achieved by adjusting the physical parameters, including orifice diameter, spinning rate and particle concentration, etc. Owning to a wide temperature operation range and reliable working mechanism, the proposed MR grease S&A device is expected to have extensive application prospects in small and medium caliber fuze systems.