金属泡沫断裂韧性的试验研究

金属泡沫在其实际应用中,断裂性能和断裂韧性对于承载的多孔金属泡沫有着重要的意义。基于美国试验材料学会相关标准,采用三点弯曲试样测定了铝泡沫的I型断裂韧性。研究表明,金属泡沫的断裂为脆性断裂,在裂纹尖端附近,孔壁最薄弱的区域最容易发生变形;随着进一步加载,一些孔壁发生断裂,微裂纹在断裂尖端附近出现。随着载荷的增加,主裂纹在缺口根部形成或由微裂纹合并而成,并开始在多孔结构内传播。裂纹沿着结构最薄弱处传播,并产生次生裂纹和裂纹桥。裂纹总的扩展方式还是I型断裂。根据试验P-V曲线特点,取最大载荷点对应的力与位移求解出铝泡沫的裂纹尖端临界张开位移的平均值为0.051 mm。     

一种新的复合导引头多源异步信息融合精确拦截算法

针对单一制导体制难以满足现代战场作战需求,而多传感器数据更新率不同步的问题,建立一种新的微惯导/毫米波/红外复合制导体制,研究了该体制下多传感器异步信息融合的时间同步和空间配准问题;提出一种自适应Unscented卡尔曼滤波算法,该算法采用预测残差构造状态模型误差统计量,通过自适应因子调整状态模型信息对状态参数估值的贡献,有效控制状态模型噪声异常对状态参数估值的影响。将提出的算法应用到微惯导/毫米波/红外复合制导系统中进行仿真验证,结果表明,提出的自适应Unscented卡尔曼滤波算法的解算精度高于标准扩展卡尔曼滤波和Unscented卡尔曼滤波算法,能有效提高导弹的制导的解算精度。     

多约束下的高超声速飞行器三维非线性自适应末制导律

面向多约束下高超声速飞行器末制导过程中的通道耦合、参数扰动、模型失配等突出问题,设计一种适于高超声速飞行器的三维非线性自适应末制导律。为了模型描述的完整性和简洁性,引入视线旋量和旋量速度的概念,并基于此建立三维制导参考模型和实际系统的表达式;为了保证制导律的鲁棒性和自适应性,基于自适应控制理论,设计一种三维非线性自适应制导律;通过数学推导证明了该制导律的稳定性。该制导律能够从理论上克服高超声速飞行器末制导面临的通道耦合、参数扰动、模型失配等突出问题,满足多约束制导要求。仿真结果验证了所设计制导律的有效性。     

复合导引头多源异步信息融合精确拦截算法

针对单一制导体制难以满足现代战场作战需求且多传感器数据更新率不同步的问题,建立一种新的微惯导/毫米波/红外复合制导体制,研究了该体制下多传感器异步信息融合的时间同步和空间配准问题;提出一种自适应无迹卡尔曼滤波算法,该算法采用预测残差构造状态模型误差统计量,通过自适应因子调整状态模型信息对状态参数估值的贡献,有效控制状态模型噪声异常对状态参数估值的影响。将提出的算法应用到微惯导/毫米波/红外复合制导系统中进行仿真验证,结果表明,提出的自适应无迹卡尔曼滤波算法的解算精度高于标准扩展卡尔曼滤波和无迹卡尔曼滤波算法,能有效提高导弹的制导的解算精度。     

含轴间距误差的消隙齿轮刚柔耦合动力学仿真

轴间距误差对消隙齿轮精度和性能有重要影响,但其机理和规律并不清楚。基于接触碰撞力约束关系建立齿轮接触动力学模型,进一步利用ADAMS/Flex建立单级消隙齿轮传动系统的刚柔耦合模型,通过刚柔耦合动力学仿真研究消隙齿轮传动在不同轴间距制造误差条件下的振动及频率特性。研究发现:随着轴间距的减小,扭簧的平均力矩增大,齿轮齿面间的啮合力矩以及摩擦力矩也将增大,从而阻碍扭矩的正常传递,并导致固定齿轮转速幅值降低;随着轴间距的增大,固定齿轮主谐振频率整体上降低,而且在轴间距稍大于标准中心距时降低很快。这一发现可指导消隙齿轮传动的设计和装配。     

利用实际飞行数据插值的INS/GNSS组合导航仿真轨迹发生器

针对INS/GNSS组合导航仿真中捷联惯导系统陀螺、加速度计信号高精度模拟问题,提出基于实际飞行数据插值的动态轨迹解析生成仿真算法。对转换到地心惯性坐标系中的载体姿态、位置和重力场数据进行关于时间的样条函数插值,得到载体坐标系下陀螺角速率、角增量以及加速度计比力积分增量的高精度分段解析表达式。使生成的陀螺、加速度计信号符合载体运动学和动力学特性,反映杆臂效应影响,同时与经事后处理的实测GNSS伪距、伪距率等数据特征保持一致。提出四元数约束插值算法,其可满足四元数解析插值时范数为1的约束限制条件。基于某实际无人机飞行数据,验证了所提算法的有效性,其完全满足组合导航动态仿真精度要求。该算法也适用于其他高精度高动态导航系统和刚体运动控制仿真中的角运动、线运动传感器信号模拟。     

水面舰艇作战指挥效能的灰色模糊综合评估法

通过对水面舰艇作战指挥系统组成及实施指挥过程的分析,建立其作战指挥效能评估的二级指标体系.基于灰色模糊数学理论,提出了水面舰艇作战指挥效能评估的灰色模糊综合评估法.该方法能更有效地解决既带模糊性又带灰色性的作战指挥效能评估问题.     

Integrated guidance and control of guided projectile with multiple constraints based on fuzzy adaptive and dynamic surface

Based on fuzzy adaptive and dynamic surface (FADS), an integrated guidance and control (IGC) approach was proposed for large caliber naval gun guided projectile, which was robust to target maneuver, canard dynamic characteristics, and multiple constraints, such as impact angle, limited measurement of line of sight (LOS) angle rate and nonlinear saturation of canard deflection. Initially, a strict feedback cascade model of IGC in longitudinal plane was established, and extended state observer (ESO) was designed to estimate LOS angle rate and uncertain disturbances with unknown boundary inside and outside of system, including aerodynamic parameters perturbation, target maneuver and model errors. Secondly, aiming at zeroing LOS angle tracking error and LOS angle rate in finite time, a nonsingular terminal sliding mode (NTSM) was designed with adaptive exponential reaching law. Furthermore, combining with dynamic surface, which prevented the complex differential of virtual control laws, the fuzzy adaptive systems were designed to approximate observation errors of uncertain disturbances and to reduce chatter of control law. Finally, the adaptive Nussbaum gain function was introduced to compensate nonlinear saturation of canard deflection. The LOS angle tracking error and LOS angle rate were convergent in finite time and whole system states were uniform ultimately bounded, rigorously proven by Lyapunov stability theory. Hardware-in-the-loop simulation (HILS) and digital simulation experiments both showed FADS provided guided projectile with good guidance performance while striking targets with different maneuvering forms.     

空对地定向攻击的作战效能评估

主要研究攻击机在定轴发射导弹时,对地面线状目标定向攻击的作战效能评估。攻击机飞向目标区的方式有两种,即攻击机飞向目标区的速度方向与线状目标的长边成一固定角和平行于该长边。详细研究了该攻击机的可攻击区边界,给出了攻击机机动攻击目标的最近距离,从而确定了作战效能评估的数学模型。     

Clustered coverage orienteering problem of unmanned surface vehicles for water sampling

This study investigates a clustered coverage orienteering problem (CCOP), which is a generalization of the classical orienteering problem. The problem is widely motivated by the emerging unmanned techniques (eg, unmanned surface vehicles and drones) applied to environmental monitoring. Specifically, the unmanned surface vehicles (USVs) are used to monitor reservoir water quality by collecting samples. In the CCOP, the water sampling sites (ie, the nodes) are grouped into clusters, and a minimum number of nodes must be visited in each cluster. With each node representing a certain coverage area of the water, the objective of the CCOP is to monitor as much as possible the total coverage area in one tour of the USV, considering that overlapping areas provide no additional information. An integer programming model is first formulated through a linearization procedure that captures the overlapping feature. A two-stage exact algorithm is proposed to obtain an optimal solution to the problem. The efficiency and effectiveness of the two-stage exact algorithm are demonstrated through experiments on randomly generated instances. The algorithm can effectively solve instances with up to 60 sampling sites.