Simulation and optimization for airdrop adaptability of overweight equipment

Airbag buffer process was analyzed with the aid of aerodynamic and thermodynamic methods.Based on the current structure of the airbag,the terminal velocity was too high.Therefore,the research on the diameter and height of the airbag was done and the feasible design area was found.With the optimized structure parameters,the airbag buffer experiment under normal conditions was conducted.Furthermore,the residual height and internal pressure of the airbag as well as the terminal velocity and acceleration of the airdrop were obtained.The experiment results show that the optimized airbag is feasible for 20 t cargo airdrop.

Extraction Phase Simulation of Cargo Airdrop System

To study the characteristics of cargo extraction, the initial phase of airdrop process, a high fidelity and extendibility simulation model with uniform motion equations for all states during extraction is developed on the basis of dynamics methods and contact models between cargo and aircraft. Simulation results agree well with tests data. Cargo exit parameters, which contribute to cargo pitch after extraction, are studied. Simplified computation model of dimensionless exit time is developed and used to evaluate the relation between extraction phase and landing accuracy. Safe interval model is introduced to evaluate the safety of extraction process. Also, relations between initial parameters, including pull coefficient, aircraft pitch and CG coefficient, etc, and result parameters, including exit time, cargo safety, pitch, etc, are developed to help design of airdrop system, especially the selection of extraction parachute and cargo deployment.

A Bio-Inspired Flapping-Wing Robot With Cambered Wings and Its Application in Autonomous Airdrop

Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some ingenious flapping-wing robots have been designed during the past two decades, development and application of autonomous flapping-wing robots are less successful and still require further research. Here, we report the development of a servo-driven bird-like flapping-wing robot named USTBird-I and its application in autonomous airdrop.Inspired by birds, a camber structure and a dihedral angle adjustment mechanism are introduced into the airfoil design and motion control of the wings, respectively. Computational fluid dynamics simulations and actual flight tests show that this bionic design can significantly improve the gliding performance of the robot, which is beneficial to the execution of the airdrop mission.Finally, a vision-based airdrop experiment has been successfully implemented on USTBird-I, which is the first demonstration of a bird-like flapping-wing robot conducting an outdoor airdrop mission.

Environment Adaptability Evaluation for Buffering Airbag of Heavy Equipment During Airdrop Landing

Aimed at the difficulties in analyzing the buffer characteristics of airbag system by using thermodynamic or experimental method only,the finite element method was used to establish nonlinear models for heavy equipment and its airbag system.The models' efficiency and correctness were validated by using on-site experiment data in vehicle airdrop landing.The simulation results agree very well with the experiment results.Then,the environment adaptability of airbag system of heavy equipment under high-altitude condition was studied by using the models.Finally,some solutions were given to solve the overturn problem in the landing.

彩虹表在溯源取证中的应用

随着无线网络传输技术的发展及经济利益的驱动,近年来利用隔空投送(AirDrop)进行无线传输已渐成规模。AirDrop可匿名发送、无需联网,因此难以对其进行追踪,成为技术人员溯源的一大难题。提出一种应用彩虹表时空折中原理的溯源技术,精确匹配发送手机号码的取证方法,突破了匿名溯源技术难题。

面向空投的青藏高原风场大涡模拟研究

青藏高原地形复杂且气候恶劣,对高原空投伞降和航空安全是巨大的挑战;本文基于数值模拟方法,研究一套适用于高原复杂地形的风场精确模拟方法。本研究首先基于WRF(Weather Research and Forecasting)模式的大涡模拟LES(Large Eddy Simulation)方案,研究青藏高原大涡模拟方法,构建一套降尺度至40 m水平分辨率的WRF-LES系统。然后,基于青藏高原大风个例,通过敏感性试验研究,评估LES方案和地形高程数据对风场模拟影响。其外,对LES方案的标准亚格子湍流应力模型中参数进行分析,得到青藏高原风场模拟的最优方案组。最后,进行批量试验,检验该方案对高原风场模拟的适用性。试验结果表明:(1)40 m分辨率的WRF-LES系统可模拟得到更精细和准确的风场信息,模拟风速平均绝对误差MAE(Mean Absolute Error)较ACM2方案减小1.4 m·s^(-1)且均方根误差RMSE(Root Mean Square Error)减小1.81 m·s^(-1);(2)高精度地形资料ASTER的接入可以改善模式对风场模拟的效果,各项误差较模式默认地形模拟结果均存在约0.2 m·s^(-1)的改善;(3)LES方案采用基于1.5阶湍流动能方案且常数项系数为0.1时模拟效果最佳,MAE为1.56 m·s^(-1)且RMSE为2.06 m·s^(-1)。批量试验验证了大涡模拟方案对于青藏高原边界层风场模拟具有较强的适用性,40 m分辨率区域风场模拟效果明显优于中尺度模拟效果,可为高原空投伞降提供准确的风场信息。

基于模型的空投任务飞行品质试飞设计及评估

重装空投飞行试验过程中,货物运动会导致飞机姿态变化过大,影响飞行安全;为了保证重装空投飞行试验安全,建立了空投过程数学模型,预测空投过程飞机响应、使用“预测→验证→比较→预测”的方法指导飞行试验循序渐进实施;在空投试飞前,分析空投货物时飞机响应特点,确定载机平台飞行品质试飞内容,评价空投构型飞行品质,作为空投飞行试验的前提;对于空投任务飞行试验设计从试飞状态选择、试飞员操纵方法设计两方面开展研究,以飞机姿态控制为目标,确定重力空投、牵引空投过程飞机飞行状态、给出飞行员操纵建议,设计了空投过程评价要素表,形成面向空投任务的飞行试验设计及飞行品质评价技术;提出的基于模型的试验设计方法及飞行品质评价方法可以有效保障空投任务执行,并全面充分地评价空投任务下的飞行品质。

Structural Design Study of Air-Dropped Unmanned Maritime Mobile Search and Rescue Platforms

In order to improve the efficiency and safety of search and rescue(SAR)at sea,this paper proposes a kind of emergency rapid rescue unmanned craft(air-dropped unmanned maritime motorized search and rescue platform)that can be delivered by a large transport aircraft.This paper studies the structural design scheme of the platform,and the main scale of the platform,the choice of power system and the impact resistance performance are considered in the design process to ensure its rapid response and effective rescue capability under complex sea conditions.Simulation results show that the platform can withstand the impact of air injection into the water and the shipboard equipment can operate normally under the impact load,thus verifying the feasibility and safety of the design.This study serves to improve the maritime search and rescue system and enhance the oceanic emergency response capability.

空降车辆着陆缓冲过程系统建模仿真研究综述

系统建模仿真作为空降车辆着陆缓冲研究的重要手段,用于仿真着陆缓冲阶段的气囊排气压缩、车辆缓冲过载、姿态变化及结构冲击响应。从系统建模、匹配设计、半实物试验、空投适应性4个方面进行评估,综述现有研究应用的理论、方法和研究结论。对目前仿真模型求解效率,结构应力和气囊仿真准确度,车辆与气囊参数匹配,半实物试验,空投适应性评估等问题进行分析总结并提出进一步的研究方向。

Variable Structure Control of Catastrophic Course in Airdropping Heavy Cargo

The mathematical model of a transport aircraft would be subjected to a sudden change when heavy cargo is dropped off in airdropping, which exerts serious influences upon the safety of the aircraft. A variable structure controller is specially designed for handling the airdrop process. The nonlinear system is linearized by input-output feedback linearization using differential geometry theories. On this basis, an inner loop system for velocity and attitude tracking control is designed by using the exponentially approaching rule of the variable structure theory. The whole flight control system is integrated with the outer loop flight altitude control. Digital simulation evidences the applicability of the system to potentially catastrophic course in airdropping heavy cargo and provides robustness against system parameter perturbation.

某储运发箱着陆缓冲特性仿真与试验验证

目的研究排气型气囊作用下某储运发箱空投着陆缓冲性能。方法建立储运发箱-气囊空投系统的LS-DYNA有限元模型,计算空投系统着陆缓冲过程的动力学响应。根据空投安全阈值,对火箭弹过载、火箭弹轴向力、各部件结构应力等进行分析。通过搭建缓冲试验平台,对仿真模型准确性进行验证。结果受冲击较大的火箭弹过载略大于30g,框架某隔板处应力超出许用应力,应注意防护。测试结果与仿真结果一致性较好,误差在±10%以内。结论本文建立的仿真模型精度较高,能满足工程需要。本文研究方法和结果对于储运发箱结构设计、着陆缓冲方案设计有一定参考意义。

Parachute dynamics and perturbation analysis of precision airdrop system

To analyze the parachute dynamics and stability characteristics of precision airdrop system, the fluid-structure interaction （FSI） dynamics coupling with the flight trajectory of a para- chute payload system is comprehensively predicted by numerical methods. The inflation behavior of a disk-gap-band parachute is specifically investigated using the arbitrary Lagrangian Euler （ALE） penalty coupling method. With the available aerodynamic data obtained from the FSI sim- ulation, a nine-degree-of-freedom （9DOF） dynamic model of a parachute-payload system is built and solved to simulate the descent trajectory of the multi-body dynamic system. Finally, a linear five-degree-of-freedom （5DOF） dynamic model is developed, the perturbation characteristics and the motion laws of the parachute and payload under a wind gust are analyzed by the linearization method and verified by a comparison with flight test data. The results of airdrop test demonstrate that our method can be further applied to the guidance and control of precision airdrop systems.

重心布置及漂角对空投气垫艇纵稳性影响分析

为了分析空投气垫艇在不同重心位置和漂角下的纵摇运动响应,利用STAR-CCM+平台的重叠网格技术对气垫艇在规则波中的水动力性能进行数值模拟。研究表明,重心和漂角的变化对空投气垫艇阻力性能和航行稳定性的影响十分敏感,试验中通过改变压块来调整气垫艇重心位置,在低速段即0.4<F_(r)<0.8时,重心纵向位置前移与垂向位置上移将会导致阻力增加,而当其在高速段即F_(r)>0.8时,重心纵向位置前移和垂向位置下移将导致阻力减少,为了满足高速船舶性能,因此重心位置布置时宜适当前移。在0°<β<30°范围内,漂角越小,气垫艇受到波浪的激励作用愈加明显,纵摇运动响应幅值越大。优化重心布置方案漂角等组合形式能够有效提升气垫艇的航行稳定性,综合分析可知该型气垫艇在重心位置靠近艏部且以一定小角度漂角高速航行时,纵向稳定性越高且兴波阻力性能最佳。

Development of an efficient contact-friction model for high-fidelity cargo airdrop simulation

High-fidelity cargo airdrop simulation requires the contact dynamics between an aircraft and a cargo to be modeled accurately. This paper presents a general and efficient contact-friction model for simulation of aircraft-cargo coupling dynamics during airdrops. The proposed approach has the same essence as that of the finite element node-to-segment contact formulation, which leads to a flexible, straight forward, and efficient code implementation. The formulation is developed under an arbitrary moving frame with both the aircraft and the cargo being treated as general six-degree-of-freedom rigid bodies, and thus it eliminates the restrictions of lateral symmetric assumptions in most existing methods. Moreover, the aircraft-cargo coupling algorithm is discussed in detail, and some practical implementation details are presented. The accuracy and capability of the present method are demonstrated through three numerical examples with increasing complexity and fidelity.

物资无伞空投用缓冲材料研究进展

目的为促进无伞空投用缓冲材料的研究和应用,改进和优化无伞空投用缓冲材料性能,为我国物资投送提供更可靠、更高效的保障支撑。方法在无伞空投用缓冲材料研究现状综述的基础上,比较不同材料的缓冲性能特点及适用性。结果随着缓冲材料技术的不断进步,传统缓冲材料结合泡沫金属、智能材料等新型复合缓冲材料,能够有效提高物资着陆安全性与稳定性,降低装备损坏与维修成本,提升抢险救援效率。结论无伞空投用缓冲材料未来发展方向为提高缓冲性能和稳定性,关注绿色环保包装材料、吸能缓冲材料、创新物资包装方式以及集成信息化智能材料,以满足各类物资对无伞空投缓冲材料的需求。

Safety modeling and simulation of multi-factor coupling heavy-equipment airdrop

Heavy-equipment airdrop is a highly risky procedure that has a complicated system due to the secluded and complex nature of factors＇ coupling. As a result, it is difficult to study the modeling and safety simulation of this system. The dynamic model of the heavy-equipment airdrop is based on the Lagrange analytical mechanics, which has all the degrees of freedom and can accurately pinpoint the real-time coordinates and attitude of the carrier with its cargo. Unfavorable conditions accounted in the factors＇ models, including aircraft malfunctions and adverse environments, are established from a man-machine-environment perspective. Subsequently, a virtual simulation system for the safety research of the multi-factor coupling heavy-equipment airdrop is developed through MATLAB/Simulink, C language and Flightgear software. To verify the veracity of the theory, the verification model is built based on dynamic software ADAMS. Finally, the emulation is put to the test with the input of realistic accident variables to ascertain its feasibility and validity of this method.

空投物出舱过程运动参数影像测量方法研究

根据某飞机货物空投运动参数的测量需求,针对狭长的货物运动空间进行近景拍摄,但是采用常规双站影像测量手段存在局限性。因此,构建8-高分辨率摄影相机组合交会测量场,研究基于组合标定的相机位姿关系解算方法,将测量场内相机纳入同一基准,有效解决复杂背景下编码标志判读问题,并完成测量原理试验验证与精度分析。

不同缓冲方式下发电机空投跌落冲击仿真与性能分析

目的比较空投发电机的2种缓冲方案的优缺点并确定防护区域。方法基于ANSYS/LS_DYNA有限元分析软件,建立发电机空投三维仿真模型,对其跌落冲击混凝土地面过程进行仿真,比较2种缓冲方案下发电机的损伤情况,重点分析了在着陆时发电机的形变、应力变化和破坏方式。结果根据仿真结果,采用蜂窝纸板缓冲因重量分布不均导致叶片脱落,而钢丝绳减震器能够显著降低最大应力,仅为蜂窝纸板的43.6%,但可能出现再弹起。着陆时的冲击应力主要集中在发电机底部外壳、连接轴和柴油机底座。结论利用有限元软件仿真分析发电机的跌落冲击是可行和有效的,可以比较不同缓冲方法的效果,极大地降低了试验成本,并可用于空投发电机的安全设计与评估。

车辆载人空降的试验与仿真研究

随着现代战争模式的发展,载人空降技术受到越来越多的重视,空降载荷下乘员的安全防护是载人空降的核心问题之一。为此,开展车辆载人空降试验,测试车辆结构响应和乘员损伤响应;建立整车和乘员约束系统有限元模型,采用整车加速度边界施加到乘员约束系统上的仿真方法开展车辆载人空降仿真;结合试验和仿真结果,研究空降冲击下车辆结构的动态响应特性及乘员损伤规律。针对触地速度、悬架弹簧刚度、阻尼参数和坐垫参数4个结构参数,以乘员下胫骨力、盆骨加速度、动态响应指标为指标,进行单因素仿真分析和正交试验仿真分析,研究空降冲击下4个结构参数对乘员损伤的影响规律。研究结果表明:采用的仿真方法能够较好地反映空降冲击下的车辆结构响应和乘员损伤响应;空降冲击下,乘员易受损部位主要有下肢、盆骨和腰椎,其中下肢损伤主要由地板直接冲击造成,盆骨和腰椎损伤由通过车体-立柱-座椅传递到乘员上身的冲击造成;触地速度对乘员损伤的影响最为显著,悬架弹簧刚度、阻尼和坐垫硬度也在一定程度上影响了乘员损伤程度;该研究成果有利于理解空降冲击下车辆结构动态响应特性和乘员损伤机理,对载人空降车辆的设计具有一定的指导意义。

装备空投多体系统动力学建模与仿真方法研究进展

装备空投是将装备向指定的地面区域快速投送的技术,拥有快速响应和长距离作战的特点。装备空投系统是典型的多体系统,目前,仍然面临落点精度及安全性等关键瓶颈问题,与空投所涉及的流固耦合、强非线性、接触碰撞、大变形结构动力学密切相关。因此,该文从多体系统动力学建模、动力学性能预测与优化设计等方面综合阐述装备空投的国内外研究进展,总结装备空投的研究发展趋势以及技术难题,指出了提高装备空投精度和安全性的前沿研究方向。