AUTOMATIC FINIT EELEMENT MODELING OF A WING

研究了建立机翼有限元模型的自动化。用行列法标识结构的部件（肋、梁、蒙皮、立柱），并用简单明了的表格界面来输入所有部件的几何、网格密度、材料、载荷、边界条件等参数。设计并用ＰＣＬ（ＰＡＴＲＡＮｃｏｍｍａｎｄｌａｎｇｕａｇｅｕｎｄｅｒＰＡＴＲＡＮ６．０）编制了相应的自动化建立整个机翼有限元模型的用户化程序模块。作为算例建立了ＶＦＷ６１４机翼的有限元模型并用ＮＡＳＴＲＡＮ６８进行了计算。结果表明，本方法有效和高效。

Parametric Geometric Model and Hydrodynamic Shape Optimization of A Flying-Wing Structure Underwater Glider

Combining high precision numerical analysis methods with optimization algorithms to make a systematic exploration of a design space has become an important topic in the modern design methods. During the design process of an underwater glider＇s flying-wing structure, a surrogate model is introduced to decrease the computation time for a high precision analysis. By these means, the contradiction between precision and efficiency is solved effectively. Based on the parametric geometry modeling, mesh generation and computational fluid dynamics analysis, a surrogate model is constructed by adopting the design of experiment （DOE） theory to solve the multi-objects design optimization problem of the underwater glider. The procedure of a surrogate model construction is presented, and the Gaussian kernel function is specifically discussed. The Particle Swarm Optimization （PSO） algorithm is applied to hydrodynamic design optimization. The hydrodynamic performance of the optimized flying-wing structure underwater glider increases by 9.1%.

Modeling and Motion Simulation for A Flying-Wing Underwater Glider with A Symmetrical Airfoil

The flying-wing underwater glider (UG), shaped as a blended wing body, is a new type of underwater vehicle and still requires further research. The shape layout and the configuration of the internal actuators of the flying-wing UG are different from those of "legacy gliders" which have revolving bodies, and these two factors strongly affect the dynamic performance of the vehicle. Considering these differences, we propose a new configuration of the internal actuators for the flying-wing UG and treat the flying-wing UG as a multi-body system when establishing its dynamic model. In this paper, a detailed dynamic model is presented using the Newton-Euler method for the flying-wing UG. Based on the full dynamic model, the effect of the internal actuators on the steady gliding motion of vehicle is studied theoretically, and the relationship between the state parameters of the steady gliding motion and the controlled variables is obtained by solving a set of equilibrium equations. Finally, the behaviors of two classical motion modes of the glider are analyzed based on the simulation. The simulation results demonstrate that the motion performance of the proposed flying-wing UG is satisfactory.

Modeling and Numerical Simulation of Wings Effect on Turbulent Flow between two contra-rotating cylinders

Many industries in the world take part in the pollution of the environment. This pollution often comes from the reactions of combustion. To optimize these reactions and to minimize pollution, turbulence is a funda- mental tool. Several factors are at the origin of turbulence in the complex flows, among these factors, we can quote the effect of wings in the rotating flows. The interest of this work is to model and to simulate numeri- cally the effect of wings on the level of turbulence in the flow between two contra-rotating cylinders. We have fixed on these two cylinders eight wings uniformly distributed and we have varied the height of the wings to have six values from 2 mm to 20 mm by maintaining the same Reynolds number of rotation. The numerical tool is based on a statistical model in a point using the closing of the second order of the transport equations of the Reynolds stresses (Reynolds Stress Model: RSM). We have modelled wings effect on the flow by a source term added to the equation tangential speed. The results of the numerical simulation showed that all the average and fluctuating variables are affected the value of the kinetic energy of turbulence as those of Reynolds stresses increase with the height of the wings.

Nanoindentation Mechanical Properties and Structural Biomimetic Models of Three Species of Insects Wings

Mimicking insect flights were used to design and develop new engineering materials. Although extensive research was done to study various aspects of flying insects. Because the detailed mechanics and underlying principles involved in insect flights remain largely unknown. A systematic study was carried on insect flights by using a combination of several advanced techniques to develop new models for the simulation and analysis of the wing membrane and veins of three types of insect wings, namely dragonfly （Pantala flavescens Fabricius）, honeybee （Apis cerana cerana Fabricius） and fly （Sarcophaga carnaria Linnaeus）. In order to gain insights into the flight mechanics of insects, reverse engineering methods were used to establish three-dimensional geometrical models of the membranous wings, so we can make a comparative analysis. Then nano-mechanical test of the three insect wing membranes was performed to provide experimental parameter values for mechanical models in terms of nano-hardness and elastic modulus. Finally, a computational model was established by using the finite element analysis （ANSYS） to analyze and compare the wings under a variety of simplified load regimes that are concentrated force, uniform line-load and a torque. This work opened up the possibility towards developing an engineering basis for the biomimetic design of thin solid films and 2D advanced engineering composite materials.

Modeling and Experiment of a Morphing Wing Integrated with a Trailing Edge Control Actuation System

Morphing wing has attracted many research attention and effort in aircraft technology development because of its advantage in lift to draft ratio and flight performance.Morphing wing technology combines the lift and control surfaces into a seamless wing and integrates the primary structure together with the internal control system.It makes use of the wing aeroelastic deformation induced by the control surface to gain direct force control through desirable redistribution of aerodynamic forces.However some unknown mechanical parameters of the control system and complexity of the integrated structure become a main challenge for dynamic modeling of morphing wing.To solve the problem,a method of test data based modal sensitivity analysis is presented to improve the morphing wing FE model by evaluating the unknown parameters and identifying the modeling boundary conditions.An innovative seamless morphing wing with the structure integrated with a flexible trailing edge control system is presented for the investigation.An experimental model of actuation system driven by a servo motor for the morphing wing is designed and established.By performing a vibration test and the proposed modal sensitivity analysis,the unknown torsional stiffness of the servo motor and the boundary condition of the actuation mechanism model is identified and evaluated.Comparing with the test data,the average error of the first four modal frequency of the improved FE model is reduced significantly to less than 4%.To further investigate the morphing wing modeling,a wing box and then a whole morphing wing model including the skin and integrated with the trailing edge actuation system are established and tested.By using the proposed method,the FE model is improved by relaxing the constraint between the skin and actuation mechanism.The results show that the average error of the first three modal frequency of the improved FE model is reduced to less than 6%.The research results demonstrate that the presented seamless morphing wing integrated with a flexible trailing edge control surface can improve aerodynamic characteristics.By using the test data based modal sensitivity analysis method,the unknown parameter and boundary condition of the actuation model can be determined to improve the FE model.The problem in dynamic modeling of high accuracy for a morphing wing can be solved in an effective manner.

Parametric CAD Modelling of Aircraft Wings for FEA Vibration Analysis

Excessive vibration of aircraft wings during flight is harmful and may cause propagation of existing cracks in the material, leading to catastrophic failures as a result of material fatigue. This study investigates the variations of modal characteristics of aircraft wings with respect to changes in the structural configurations. We develop parametric Computer-Aided Design (CAD) models to capture new design intend on the aircraft wing architectures. Subsequent Finite Element Analysis (FEA) based vibration analysis is performed to study the effects of architecture changes on the wing’s natural frequencies and mode shapes. It is concluded that the spar placement and the number of ribs have significant influence on the wing’s natural vibration properties. Integrating CAD modelling and FEA vibration analysis enables designers to develop alternative wing architectures to implement design requirements in the preliminary design stage.

Optimization of Fairhurst-Cook Model for 2-D Wing Cracks Using Ant Colony Optimization (ACO), Particle Swarm Intelligence (PSO), and Genetic Algorithm (GA)

The common failure mechanism for brittle rocks is known to be axial splitting which happens parallel to the direction of maximum compression. One of the mechanisms proposed for modelling of axial splitting is the sliding crack or so called, “wing crack” model. Fairhurst-Cook model explains this specific type of failure which starts by a pre-crack and finally breaks the rock by propagating 2-D cracks under uniaxial compression. In this paper, optimization of this model has been considered and the process has been done by a complete sensitivity analysis on the main parameters of the model and excluding the trends of their changes and also their limits and “peak points”. Later on this paper, three artificial intelligence algorithms including Particle Swarm Intelligence (PSO), Ant Colony Optimization (ACO) and genetic algorithm (GA) has been used and compared in order to achieve optimized sets of parameters resulting in near-maximum or near-minimum amounts of wedging forces creating a wing crack.

Quantitative analysis of the morphing wing mechanism of raptors:Morphing kinematics of Falco peregrinus wing

Raptors are getting more attention from researchers because of their excellent flight abilities.And the excellent wing morphing ability is critical for raptors to achieve high maneuvering flight,which can be a good bionic inspiration for unmanned aerial vehicles(UAV)design.However,morphing wing motions of Falco peregrinus with multi postures cannot be consulted since such a motion database was nonexistent.This study aimed to provide data reference for future research in wing morphing kinetics.We used the computed tomography(CT)approach to obtain nine critical postures of the Falco peregrinus wing skeleton,followed with motion analysis of each joint and bone.Based on the obtained motion database,a six-bar kinematic model was proposed to regenerate wing motions with a high fidelity.

Analysis and Research on Equivalent Model of Airbus A380 Wing Beam

With the development of aviation industry,civil aviation has become an indispensable part.Our team will take all the structural dimensions,loads and material parameters in the wing beam structure as the specific values determined during the structural design to conduct deflection analysis on the wing beam structure of A380 passenger plane.According to the deflection and parameters analyzed,the stress distribution and maximum stress position on the wing beam can be known.Through the analysis of the wing parameters,the finite element analysis of the wing beam,the mesh sensitivity analysis,and the analysis of the wing tip deflection,the relevant safety factors of the aircraft are obtained.The results show that the wing of airbus A380 is more reliable and safer through the calculation of deflection,stress and safety factor.

Mathematical Model for Takeoff Simulation of a Wing in Proximity to the Ground

飞机飞结束到从提高的效率由于的扎根的利益减少导致拖并且增加的电梯。在这研究，一个数学模型被开发用一个反复的边界元素方法(IBEM ) 和有限差别计划在地面附近模仿一个翅膀的起飞。二独立亚代码和母亲代码，启用在亚代码之间的通讯，被开发为 Wing-In-Ground (假发) 效果的自激解决。在翅膀上施加的空气动力学的力量被第一亚代码用 IBEM 计算，并且翅膀的垂直排水量由用有限差别计划的第二亚代码是计算的。二亚代码和罐头在秒以内为翅膀和操作高度的气体动力学解决的母亲代码命令。发达代码系统被用来为一个 NACA6409 翅膀的力量，速度，和排水量解决在一 40，和 20 ?

一种小型火工机构的输出计算及其验证

针对某折叠翼展开机构的小型化难题,研究了一种小型火工机构。利用内弹道理论建立了该火工机构的输出理论模型,通过理论模型计算和优化了机构参数,并用有限元法校验了计算结果。测试结果表明:该原型机具备了小型特点,其输出角度达到了128.5°。在逆风和顺风负载下,该火工机构的工作时间均小于200 ms,其最大角速度不大于3 000 (°)/s,试验数据证实该火工机构具备缓冲作用,理论计算结果和试验数据基本一致。研究成果可作为薄型折叠翼的一种设计方法,为薄型折叠翼的工程应用奠定技术基础。

四川地区精细化降水预报融合订正试验及检验

精细化定量降水网格预报是天气预报业务的重点和难点,基于西南区域智能数值网格模式预报系统(Southwest China WRF-based Intelligent Numeric Grid forecast System,SWC-WINGS)1 km×1 km分辨率的小时降水预报,利用时间滞后和概率匹配方法开展融合订正试验,再利用中国气象局多源融合降水系统(CMA Multi-source Precipitation Analysis System,CMPAS)三源融合降水实况格点数据,对2022年7—8月四川地区的小时降水预报融合订正结果进行检验,并在四川盆地西部一次短时强降水天气过程中进行应用,结果表明:(1)时间滞后集合降水预报相较于模式降水预报,存在小量级预报过度,大量级预报过于保守的问题;(2)时间滞后结合概率匹配的降水预报融合订正方法有效提升了各量级降水预报的TS评分,尤其1~2 h预报时效提升显著,小时雨量超过0.1 mm、5 mm、10 mm和20 mm量级的TS评分平均提升率分别为7.2%、17.2%、28.3%和36.3%;(3)一次短时强降水天气过程的应用结果表明,时间滞后结合概率匹配的融合订正方法对模式小时降水预报有较好的改进效果,尤其对大量级降水预报有较强的订正能力。

应用于水陆两栖勘测及紧急救援的仿生机械龟

针对现有水下航行器能耗高、噪声大、续航能力一般等问题,通过探索水下仿生扑翼的推进机理,结合流体力学运动的知识,利用SolidWorks仿造龟的外形设计了仿生机械龟。该机械龟装载浮力与重力感应系统,通过PID算法控制机器在水中的平衡,使用Arduino作为主控制板,利用传感器、摄像系统与数据传输系统,进行实时监测并传输数据,龟壳中设计了贮藏空间,满足勘测和物资救援任务。实验结果表明,所设计的水陆两栖仿生机械龟优化了形态和运行控制系统,对比美国耶鲁大学研制出的仿乌龟形水陆两栖机器人ART,能够适应多样化地形高效的运动,具有高灵活性和机动性,能完成对水中温度、压强、地形进行实时监测并将数据传输回终端。

带襟翼导轨翼肋后缘尺寸-拓扑综合优化的摄动神经网络代理模型法

带襟翼导轨的翼肋后缘设计需要确定肋缘条、腹板的尺寸和肋腹板的拓扑形状,对此提出了一种针对尺寸-拓扑综合优化的摄动神经网络(perturbation neural network, PNN)代理模型法.其基本思想是基于拓扑优化对参数的敏感性,引入了对试验设计(design of experiments, DOE)样本点的摄动,通过过滤手段捕获拓扑突变点,并降低数值噪声,极大地提高了代理模型的预测精度,将拓扑优化过程作为黑盒,直接建立起尺寸变量与拓扑优化后结构响应的代理模型.最后在代理模型上进行优化,得到了结构尺寸与拓扑形状的最优组合.该文完成了一个翼肋后缘优化典型算例,证明了该方法的有效性和优越性.

无人机折叠翼分步展开机构设计及动力学分析

小型巡飞无人机折叠翼的展开方案对于无人机飞行模式切换具有重要影响。针对无人机折叠翼折叠特点与展开需求,提出同步展开和分步展开2种方案。采用拉格朗日法建立折叠翼展开动力学模型,应用气动力仿真软件计算折叠翼在展开过程中所受空气阻力,得出折叠翼采用不同展开方案时所需驱动力矩,以驱动力矩作为评判标准,选取折叠翼最优展开方案。仿真计算结果表明,折叠翼分步展开方案可在保证展开到位的情况下,以小力矩在短时间内完成展开运动。针对折叠翼分步展开方案设计折叠翼分步展开机构,并进行结构静强度分析,验证结构方案的可行性。

可变弯度翼身融合布局气动特性分析与设计

变弯度机翼在提高常规布局客机气动特性方面有较大的潜力,但也会引起全机俯仰力矩变化,考虑翼身融合布局飞行器力臂短、配平阻力较大的特点,研究变弯度技术在翼身融合布局飞行器上的减阻收益与配平惩罚。从工程实际出发,采用基于舵面偏转的方式实现后缘变弯度并对比分析不同展向位置处舵面的配平能力;然后利用全局优化方法开展变弯度气动减阻优化设计;最后对变弯度设计空间进行探索。结果表明:随着升力系数的改变,产生配平阻力最小的舵面位置也会发生变化。当不考虑俯仰力矩配平约束时,采用变弯度技术至多可以获得4.62%的减阻收益;在考虑俯仰力矩配平约束后,相比于采用中央体后缘舵面配平,采用变弯度技术至少能够减小2.4×10^(-4)的配平损失。不同升力系数下,变弯度的舵面偏转组合方式存在明显差异,小升力系数下,多个舵面负偏的变弯度组合有利于减阻并增加抬头力矩;而大升力系数下则是通过多个舵面正偏的组合实现减阻,但会导致低头力矩增加。基于多舵面组合偏转的变弯度减阻收益与力矩惩罚评估,能为工程上设计可变弯度翼身融合布局飞行器提供参考。

鱼骨柔性翼等效结构建模及其气动弹性特性分析

鱼骨柔性翼(Fish bone active camber,FishBAC)是一种依靠结构变形实现机翼弯度变化的结构形式,相较于传统的离散式控制面和增升装置,可以在实现机翼弯度变化的同时保持气动表面的连续与光滑。然而,其依靠结构弹性变形实现机翼变弯度的基本特征可能引发潜在气动弹性问题。针对柔性翼潜在的气动弹性问题,本文从结构特性和气动弹性特性两方面进行了研究。在结构特性方面,基于欧拉梁理论和逐段刚化法建立等效结构模型,经有限元验证发现简化模型在计算非均质梁结构保持精度的同时提高了计算效率。在气动弹性特性分析方面,基于等效刚柔耦合翼型模型和非定常气动理论完成了气动弹性特性分析。结果表明,FishBAC建模时需考虑结构柔性,忽略结构柔性会对气动弹性特性的预测存在一定偏差。在驱动力矩低于1.5 N·m时,本文简化的等效结构模型可较好地预测考虑静气动弹性特性的机翼结构形变。使用本文提出的翼型模型考虑结构存在刚柔耦合特性,并预测柔性段所发生的弯度颤振,简化模型与MSC Nastran相比在颤振速度预测上保持了一致性。

考虑强风干扰的固定翼飞行器“神经元”飞行气动建模

大气环境中的风是影响飞行器实际飞行的主要动态环境干扰因素之一,强风干扰下的复杂空气动力学是固定翼飞行器安全稳定飞行面临的严峻挑战。为提高强风干扰下固定翼飞行器的环境适应能力,发展了一种基于深度元学习的创新固定翼飞行器“神经元”飞行气动建模方法,该方法采用相对于地面坐标系的变量进行描述,根据多元函数的切比雪夫级数理论,将气动力和气动力矩函数分解为不同变量函数的乘积和,通过生成对抗网络技术构建强风干扰下飞行器空气动力模型的共性基函数模型,进而预测飞行器在飞行过程中受到的气动力(矩)。研究结果表明,文章建立的固定翼无人机空气动力共性基函数模型准确,可以较好地预测未知风况条件下飞行器的气动力与气动力矩,为实时空气动力学建模的迁移应用奠定良好基础。