破片模拟弹侵彻钢板的有限元分析

根据破片模拟弹侵彻钢板的实验研究,采用MSC.Dytran对破片模拟弹侵彻钢板的侵彻过程、侵彻特性、钢板的破坏模式以及弹体的侵彻速度、靶板的侵彻阻力进行了有限元分析,并将分析结果与实验结果进行了比较.分析结果表明,破片模拟弹冲击钢装甲的侵彻过程可大致分为初始接触、弹体侵入、剪切冲塞和穿甲破坏4个阶段.有限元分析的破片模拟弹侵彻特性及靶板破坏模式与实验观测结果有较好的一致性,在靶板破口的正面,与弹体平面凸缘两端接触的部分,变形以剪切为主,而与切削面接触的部分,以挤压变形为主;靶板破口背面为剪切冲塞破坏;有限元模拟的弹体剩余速度与实验结果吻合较好,弹体侵彻过程中弹靶作用界面的速度和侵彻速度近似呈线性变化.有限元分析结果还表明,采用适当的模型,有限元法能较好地模拟破片模拟弹侵彻钢板的侵彻过程、侵彻特性以及钢板的破坏模式.     

超高速碰撞形成一次碎片云特性

对超高速碰撞数值模拟方法进行了讨论.采用ANSYS/AUTODYN程序的SPH方法,对球形弹丸超高速撞击时弹丸的破碎、碎片云的形成及扩展过程进行数值模拟,其结果与实验结果进行比较,并验证了计算方法和模型参数的正确性.在此基础上采用数值模拟方法,对钨合金、轧制均质装甲及LY12铝三种材料的球形弹丸超高速撞击靶板之后形成的一次碎片云形貌及演化规律进行了研究,并基于量纲分析方法得出了碎片云特征参数(碎片云头部速度、径向最大膨胀速度及膨胀角)随初始撞击条件的变化规律。     

月壤参数对月面着陆气囊缓冲性能的影响

为研究月壤参数对气囊缓冲性能的影响,根据“嫦娥三号”的着陆工况设计了月面着陆气囊,并基于可压溃泡沫模型建立了考虑月壤特性的气囊缓冲动力学模型。对不同月壤下气囊的缓冲过程进行分析,发现月壤越软有效载荷冲击加速度越小,但气囊会陷入月壤中,不利于对外排气,影响其缓冲效果。因此,采用气囊峰值压力、有效载荷最大加速度和最大下落高度3个指标对气囊缓冲性能进行综合评价,定量研究了月壤参数的影响规律。结果表明:月壤密度、剪切模量及屈服参数a₀和a₁对缓冲性能的影响较大,且对前两个指标为正影响,对后一个指标为负影响。进一步研究发现,这4个月壤参数与3个缓冲性能指标之间〖BHDWG8,WK10YQ,DK1*2,WK1*2D〗〖XCZX.TIF;%129%129〗听语音 聊科研与作者互动 均为指数函数关系。     

Investigation of normal,lateral, and oblique impact of microscale projectiles into unidirectional glass/epoxy composites

Spacesuits and spacecraft must endure high velocity impacts from micrometeoroids. This work considers the impact of 100 μm diameter projectiles into composite targets at velocities from 0.5 km/s to 2 km/s. This work begins by presenting an energy-based theoretical model relating depth of penetration (DoP) and impact force to impact velocity, characteristic time, and threshold velocity and force. Next, this work compares numerical simulations of normal impact on composites to the theoretical model. Numerical simulations are conducted with LS-DYNA and the well-known composite model, MAT-162. The numerical models consider unidirectional S2-glass fiber reinforced SC-15 epoxy composite laminates. The numerical model shows good correlation with the theoretical model. The numerical model also investigates lateral impact, parallel to the fiber direction, and oblique impact at angles from 30° to 82.5°. This work decomposes oblique impact into normal and lateral components, and compares them with normal and lateral impact results. The results show good correlation of the normal component of oblique results with the theoretical model. This numerical and theoretical study focuses on DoP, velocity, and penetration resistance force as functions of time. The theoretical model and numerical simulations are used to determine new DoP parameters: characteristic time of depth of penetration and threshold impact velocity. These models are a first step in developing the capability to predict DoP for oblique, microscale, high-speed impact on composite materials.     

基于数据场的登陆作战体系兵力编组效能分析

兵力编组效能直接影响登陆作战体系的作战能力。在分析梯队式和群队式兵力编组模式下登陆作战体系网络模型的基础上,利用数据场理论研究登陆作战体系的拓扑势场,描述梯队或群队间由支援、协同产生的协同作战能力,建立基于数据场的登陆作战体系兵力编组效能模型,并进行仿真分析。得到了一种定量分析兵力编组作战效能的方法。     

基于模拟退火的P SO算法在舰载机回收中的应用

在舰载机回收过程中,着舰指挥官要综合考虑剩余油量、战损、气象条件等不确定因素的影响,对舰载机进行实时调度,确定安全快速的着舰次序。建立了舰载机着舰回收模型,给出着舰风险成本函数,利用具有全局搜索能力的粒子群算法对目标函数最优化处理,为避免算法陷入局部最优,选择具有突跳能力的模拟退火算法进行局部搜索。仿真结果证明,基于模拟退火的粒子群算法具有快速收敛的优点,能寻找出合理的着舰序列。     

An investigation on anti-impact and penetration performance of basalt fiber composites with different weave and lay-up modes

The woven basalt fiber composites (WBFC) and the unidirectional [0°/90°/45°/-45°]_s basalt fiber composites (UBFC) were prepared by hot-pressing. Three-point bending test, low velocity impact test, and ballistic test were performed to the prepared composites. After the tests, the specimens were recovered and analyzed for micromorphology. Three-point bending tests show that both the bending strength and stiffness of the WBFC surpass those of the UBFC. Low velocity impact test results show that the low velocity impact resistance to hemispherical impactor of the UBFC is higher than that of the WBFC, but the low velocity impact resistance to sharp impactor of the UBFC is lower than that of the WBFC. For the ballistic test, it can be found that the ballistic property of the UBFC is higher than that of the WBFC. After the tests, microscopic analysis of the specimens was applied, and their failure mechanism was discussed. The main failure modes of the UBFC are delamination and fibers breakage under the above loading conditions while the main failure mode of the WBFC is fibers breakage. Although delamination damage can be found in the WBFC under the above loading conditions, the degree of delamination is far less than that of the UBFC.     

一类不确定语言型机降场选择模型

机降场选择是超视距垂直登陆作战的关键工作之一。针对机降场选择的决策特点,定义了不确定语言集结算子,建立了基于不确定语言型多属性群决策方法的机降场选择评估模型。该模型直观、简单,降低了对指挥员的专业素质要求,有效弥补了指挥员的主观判断误差,提高了评估决策可靠性,具有较高的应用价值。     

非法移民对边境安全稳定的影响分析

边境安全作为国家安全或者国土安全的重要方面，越来越多地受到各种非传统安全因素的威胁和挑战，其中，非法移民问题就是一个不可忽视的因素。非法移民的界定涵盖了“偷运移民”和“贩运人口”两种犯罪形式，并分别从结构性维度和战略性维度分析了非法移民对输出国（或地区）、输入国（或地区）和途经国（或地区）边境安全稳定的影响。     

恐怖活动中公众心理恐惧效应对社会稳定的影响及对策

恐怖活动往往导致公众的巨大心理恐惧效应,极易造成一定程度甚至是大规模的社会恐慌,严重影响社会稳定。因此,降低公众对恐怖袭击活动的心理恐惧效应、提高其心理承受能力,对恐怖活动发生时维护社会稳定具有重要意义。