Glare层合板的抗鸟撞分析

飞机结构的抗鸟撞性能对于飞行安全有着直接的联系,鸟撞事故一旦发生,对飞机结构、设备的破坏作用往往极为严重。针对Glare层合板材料进行了抗鸟撞分析,利用有限元方法,采用显式碰撞动力分析软件PAM-CRASH,对四种不同纤维铺层角的Glare层合平板进行了抗鸟撞仿真分析,比较选取了最优的纤维铺层角;设计了全尺寸的机翼前缘模型,对4/3和3/2两种构型的Glare层合蒙皮进行了抗鸟撞仿真。结果表明4/3构型的Glare层合蒙皮的抗鸟撞效果最好,该构型将被进一步应用于机翼抗鸟撞试验件的设计中。     

Damage sensitivity of a wing-type leading edge structure impacted by a bird

On the windward side of an aircraft, the components with higher probability of impact with birds are the wing-type leading edge structures, such as the wing and tail. A study on the damage sensitivity of a wing-type leading edge structure under bird strikes was presented in this paper. First, a bird strike test was carried out on a wing. The principles of the bird strike test equipment and method were introduced in detail, including the bird strike test system, bird projectile production process and data acquisition system. The dynamic strain measurement results, the high-speed camera videos, and the final deformation and damage morphology observations of the structure were obtained. Based on the coupled Smooth Particle Hydrodynamics (SPH) - Finite Element Method (FEM), the commercial software PAM-CRASH was used to simulate the process of a bird strike with the wing. The good agreement between the finite element simulation results and the experimental results shows that the calculation method and the numerical model presented in this paper were reasonable. On this basis, wing-type leading edge structures can be designed by adding triangular support. The bird strike resistances of an original structure and improved structure were studied by numerical simulation. The calculated results show that the improved wing-type leading edge structure is less damaged than the original structure under bird strike. The improved leading edge structure satisfied the anti-bird strike airworthiness requirements, as the thickness of the triangular support was 1.2 mm, and the weight of the structure was reduced by 0.87 kg compared with the original structure. This indicated that the bird strike resistance of the improved structure is better than that of the original structure, and the improved design of the wing-type leading edge structure presented in this paper is reasonable.     

典型前缘结构抗鸟撞性能改进研究

 针对某典型前缘结构,研究了使用纤维金属层板(Fibre Metal Laminates,FMLs)蒙皮进行抗鸟撞设计的可行性。以显式动态冲击分析程序PAM-CRASH为平台,结合由鸟撞平板试验结果验证的鸟体本构模型参数,建立了鸟撞前缘结构数值模型。通过计算研究了使用不同蒙皮(铝合金、FMLs)的前缘结构在鸟撞作用下的变形破坏模式及吸能效果。结果表明：采用适当铺层的FMLs蒙皮可以有效地提高前缘结构的抗鸟撞性能。研究结论对飞机结构的抗鸟撞研究具有一定的参考价值。     

民用飞机方向舵抗鸟撞分析研究

民用飞机方向舵结构通常位于垂尾后部,通过连接铰链与垂直安定面后缘相连,并通过作动器驱动其偏转,从而为飞机提供偏航力矩。对民用飞机方向舵鸟撞相关适航条款要求进行了分析,明确了方向舵抗鸟撞需要满足的具体要求。在完成上述工作后,对某型民机方向舵的抗鸟撞性能进行了全面的评估。首先通过工程算法,初步评估了该方向舵不同偏角下的鸟体撞击力,并以此为依据筛选出了鸟撞的严酷工况,避免了大量计算方向舵不同偏角的鸟撞情况,从而大大降低了仿真分析的工作量。通过SPH方法,使用PAM-Crash软件对方向舵结构进行了抗鸟撞分析,得到了方向舵翼面本体结构的损伤情况、连接铰链的受载情况和方向舵作动器的受载情况,并以此为依据,完成了对方向舵抗鸟撞性能的完整评估。     

民机典型前缘结构抗鸟撞分析研究

为保障飞行安全,CCAR25 部对民机结构抗鸟撞性能提出了严格的指令性要求,须对机翼前缘、平尾前缘和垂尾前缘等典型前缘结构进行鸟撞分析。鸟撞分析涉及到结构的动力学分析、鸟体的本构关系模拟、材料的高速非线性效应以及结构大变形等多方面因素的影响,相关的计算复杂,会耗费结构设计人员大量的精力和时间。通过采用经验公式和仿真分析方法对前缘结构抗鸟撞性能进行快速的分析,可达到对结构的抗鸟撞能力进行快速预估并从而指导设计的目的。     

多欧拉域耦合法在平尾鸟撞中的应用

鸟撞是威胁航空安全的重要因素之一。目前的研究多是对单一试件或结构的一次性鸟撞，而对鸟体穿透撞击部位后，对其他结构造成二次冲击的研究较少。为了研究这种问题，基于流固耦合算法，建立了多欧拉域耦合的某直升机平尾全尺寸模型。在考虑空气影响的前提下，详细分析了鸟撞平尾过程、前缘和前梁的损伤形式、平尾的位移响应、鸟撞载荷规律以及冲击载荷对平尾根部结构的影响，并与试验结果进行了对比。研究表明：鸟体在穿透前缘时未发生解体，其对前梁的二次冲击载荷同样很高，平尾结构设计需要考虑鸟撞是否会造成平尾根部断裂，鸟撞载荷具有阶跃函数的特点；结构响应时间对比冲击载荷有明显的滞后效应。     

某型飞机平尾前缘抗鸟撞优化设计

进行了某型飞机部分平尾前缘结构的抗鸟撞优化设计。通过有限元分析对比研究了蒙皮厚度、翼肋个数、隔板对平尾前缘抗鸟撞性能的影响。从分析结果可以看出,增加隔板的方案对结构抗鸟撞性能的提高最明显。然后,进行了增加隔板的平尾前缘结构鸟撞试验,试验结果与模拟结果吻合良好,满足结构的抗鸟撞要求。     

航空发动机风扇叶片的抗鸟撞设计

根据航空发动机结构特征和鸟撞后的风扇叶片损伤特征,提出风扇第一级转子叶片是发动机抗鸟撞关键零件,叶片前缘为抗鸟撞设计关键部位。建立一种风扇叶片鸟撞理论分析方法,研究撞击工况、结构参数与鸟撞过程、损伤模式、损伤程度的关系,提出前缘角度是抗鸟撞能力关键结构参数。当撞击工况确定后,前缘角度决定了撞击形式和叶片损伤模式,影响损伤程度。采用显示动力学仿真分析方法,设计了一种带前缘特征的模型,对前缘角度的影响规律进行了验证,并开展了实际风扇叶片改进设计,改进后的叶片被鸟撞击后变形减小最少33%,抗鸟撞击能力明显提升。     

大柔性飞机着陆撞击多质量块等效模型

考虑飞机结构振动刚性模态和前n阶弹性模态,将飞机机体等效地转化为多质量块等效模型,给出了等效系统力学参量的计算方法,为计及机体振动影响的起落架落震试验设计,通过试验检验或确定起落架着陆载荷、功量等提供模型依据,同时也为起落架设计分析、设计计算提供了简明的等效系统。还给出了大柔性飞机着陆功量、机翼位移、剪力、弯矩计算公式。算例结果表明大柔性飞机的起落架设计有必要考虑机体结构弹性,并从全局出发,采用特殊的构造措施和优化设计技术。     

十公斤级固定翼无人机全碳纤维机翼设计与应力分析

根据轻型固定翼无人机性能要求,设计了一款最大起飞结构质量为10 kg、质量轻、强度高、刚度高的固定翼无人机全碳纤维机翼;基于气动性能分析和结构几何设计,建立了机翼结构的三维模型;采用"封闭矩形截面缘条"盒式梁结构,增大了机翼的扭转刚度;建立了机翼结构有限元模型,采用最大应力强度准则,对机翼结构的强度、刚度、稳定性进行了校核。对蒙皮碳纤维铺层结构进行了优化。结果表明,结构应力集中区域位于翼梁根部螺栓孔区域,该区域应力水平决定了结构的初始强度;机翼大梁上缘条根部和附近的蒙皮易发生屈曲;优化后蒙皮减重121.6 g,占机翼初始结构质量的11.94%。     

民用飞机吊挂指形罩鸟撞分析

指形罩结构位于吊挂前缘,作为动力装置整流罩体的一部分,为吊挂及发动机提供气动外形,并为燃油、液压、电气、环控等系统管路提供保护和通路。指形罩的位置及功能决定了其结构必须满足鸟撞要求,承受鸟体撞击后不能影响飞机安全。通常采用鸟撞试验对指形罩结构抗鸟撞性能进行适航验证。为了降低适航验证周期和成本,一般通过鸟撞分析来降低取证试验的撞击点数量。介绍了一种吊挂指形罩鸟撞分析过程和方法,并对分析方法进行了工程试验验证,得到一种可靠的指形罩鸟撞分析方法,为类似的飞机整流结构的鸟撞分析提供了参考。     

基于MCMC方法的运输类飞机鸟撞冲击能量研究

鸟撞冲击能量是运输类飞机结构安全设计和鸟撞适航条款制定的重要基础,目前我国运输类飞机鸟撞相关研究都是参照FAA中的鸟撞冲击能量标准要求,并没有考虑我国的自然环境等特点.针对这一问题,运用马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)估计方法,采用Gibbs抽样原理,在贝叶斯理论的框架下,对我国运输类飞机鸟撞冲击能量开展了研究,在小样本条件下对鸟撞冲击能量概率分布进行估算,为后续鸟撞安全性分析提供了重要基础.     

发动机一级转子抗鸟撞试验与数值模拟研究

鸟撞发动机在鸟撞事故中最容易造成飞机损坏失事的情况,为了研究发动机一级压气机转子抗鸟撞适航性能,对发动机转子在工作状态下进行鸟撞试验,鸟体质量为1 000 g,撞击速度为195 m/s,发动机一级转子转速为8 525 r/min;基于显式碰撞动力分析软件PAM-CRASH 建立相应的叶片鸟撞数值计算模型,通过与试验结果的对比来验证本文计算模型的合理性;根据发动机适航条例分析不同工况下发动机一级转子抗鸟撞性能。结果表明：大鸟撞击相比于中鸟鸟群和小鸟鸟群,对于叶片的撞击结果更加恶劣;叶尖位置撞击会引起叶尖部位的大变形,叶根和叶中位置撞击会引起叶片根部较大的集中应力,导致叶片断裂。     

考虑鸟撞的航空发动机叶片动态拓扑优化设计

为了实现航空发动机冷端风扇叶片在考虑鸟撞情况下的轻量化设计,从结构拓扑优化计算的角度出发,对该问题展开深入的研究并提出具体的解决方案。针对叶片优化中存在的优化模型建立,结构动态工况优化,多条件约束并存处理,多工况联合优化等关键问题,进行了理论上的深入分析研究,阐述了结构多约束、多工况动态优化的理论基础,并结合相应的数值计算平台,提出了风扇叶片分步优化计算的方案,对航空发动机叶片进行拓扑优化计算。计算结果显示,最终的叶片轻量化结构满足所有鸟撞与离心载荷多工况的优化约束条件,拓扑结构中材料分布合理,在满足适航条例强度要求的同时质量减少达37.9%,具有一定的实际参考应用价值,同时所提出的动态优化计算方案,在工程结构的动态优化中具有广阔的应用前景。     

民机客舱下部吸能结构分析与试验相关性研究

以民机典型机身段客舱下部结构为研究对象,建立了结构坠撞有限元模型,利用LS-Dyna软件进行了结构能量吸收特性分析。基于吸能结构思想,以降低传递到客舱地板的加速度载荷为设计目标,提出了一种民用飞机客舱地板下部结构吸能设计方法。设计制造了全尺寸的吸能结构试件,并进行了垂直坠撞试验。为评估坠撞分析与试验的相关性,提出了一种基于能量的能量吸收特性评估方法。首先对预试验分析结果与试验结果进行了相关性分析,根据相关性分析结果对分析模型进行了修正。修正后坠撞分析结果与试验结果的相关性表明,乘员质心处的平均加速度响应峰值误差为16.44%,最大平均反弹速度误差为10.53%,修正后模型的总体刚度与实际结构一致,分析获得的结构总体变形模式与试验结果基本一致。但能量吸收时间和加速度峰值出现的时间与试验结果相比误差较大,表明结构连接失效等结构建模细节对计算结果有显著的影响。     

Integrated optimization on aerodynamics-structure coupling and flight stability of a large airplane in preliminary design

The preliminary phase is significant during the whole design process of a large airplane because of its enormous potential in enhancing the overall performance. However, classical sequential designs can hardly adapt to modern airplanes, due to their repeated iterations, long periods, and massive computational burdens. Multidisciplinary analysis and optimization demonstrates the capability to tackle such complex design issues. In this paper, an integrated optimization method for the preliminary design of a large airplane is proposed, accounting for aerodynamics, structure, and stability. Aeroelastic responses are computed by a rapid three-dimensional flight load analysis method combining the high-order panel method and the structural elasticity correction. The flow field is determined by the viscous/inviscid iteration method, and the cruise stability is evaluated by the linear small-disturbance theory. Parametric optimization is carried out using genetic algorithm to seek the minimal weight of a simplified plate-beam wing structure in the cruise trim condition subject to aeroelastic, aerodynamic, and stability constraints, and the optimal wing geometry shape, front/rear spar positions, and structural sizes are obtained simultaneously. To reduce the computational burden of the static aeroelasticity analysis in the optimization process, the Kriging method is employed to predict aerodynamic influence coefficient matrices of different aerodynamic shapes. The multidisciplinary analyses guarantee computational accuracy and efficiency, and the integrated optimization considers the coupling effect sufficiently between different disciplines to improve the overall performance, avoiding the limitations of sequential approaches utilized currently.     

Numerical simulation of a UAV impacting engine fan blades

A 3D digital model of a small Unmanned Aerial Vehicle (UAV) is obtained by using the method of scanning reverse modeling and joint mapping. A numerical simulation of a small UAV strikes on rotary engine blades, presented in this paper, was performed with a Transient Nonlinear Finite Element code PAM-CRASH software. A test of motor strike on plate was developed and the dynamic response of the plate were obtained to validate the numerical simulation method of a UAV strike on blades. Based on this, dynamic damage response caused by UAV on the engine blades were studied. It is indicated that the impact process between the UAV and a single blade can be divided into two typical stages: cutting and impact. Cutting mainly leads to the failure of the leading edge material, and impact mainly leads to the plastic deformation of the blade. At the same time, it is compared with the damage impacted by bird with the same mass. For the same mass of bird and UAV, the damage caused by UAV striking fan blade is more serious, and 1.345 kg UAV striking fan blade of typical civil aviation engine is enough to cause damage to flight safety.     

Computational aerodynamic analysis on perimeter reinforced （PR）-compliant wing

Abstract Implementing the morphing technique on a micro air vehicle （MAV） wing is a very chal- lenging task, due to the MAWs wing size limitation and the complex morphing mechanism. As a result, understanding aerodynamic characteristics and flow configurations, subject to wing structure deformation of a morphing wing MAV has remained obstructed. Thus, this paper presents the investigation of structural deformation, aerodynamics performance and flow formation on a pro- posed twist morphing MAV wing design named perimeter reinforced （PR）-compliant wing. The numerical simulation of two-way fluid structure interaction （FSI） investigation consist of a quasi- static aeroelastic structural analysis coupled with 3D incompressible Reynolds-averaged Navier- Stokes and shear-stress-transport （RANS-SST） solver utilized throughout this study. Verification of numerical method on a rigid rectangular wing achieves a good correlation with available exper- imental results. A comparative aeroelastic study between PR-compliant to PR and rigid wing per- formance is organized to elucidate the morphing wing performances. Structural deformation results show that PR-compliant wing is able to alter the wing＇s geometric twist characteristic, which has directly influenced both the overall aerodynamic performance and flow structure behavior. Despite the superior lift performance result, PR-compliant wing also suffers from massive drag penalty, which has consequently affected the wing efficiency in general. Based on vortices investigation, the results reveal the connection between these aerodynamic performances with vortices formation on PR-comoliant wing.     

螺旋桨滑流与机翼之间气动干扰影响研究

基于多参考系方法,利用RANS方程对某型螺旋桨飞机的全机有滑流和无滑流空间流场进行了数值模拟,分析了滑流在机翼干扰作用下的发展趋势,机翼气动特性在滑流作用下的改变,滑流对飞机失速特性的影响。研究结果表明,螺旋桨旋转卷起的涡流经机翼时被切割成上下两部分,形成了绕机翼的横向二次流,机翼的存在改变了滑流的涡量分布和涡的结构。在弦向,滑流影响最严重的部位是机翼前缘,滑流旋转效应改变了机翼绕流的当地迎角,加速效应增加了桨后气流的速度,这是引起机翼气动特性改变的主要原因。虽然滑流的诱导作用使机翼外段提前发生了分离,但是其推迟了机翼根部分离现象的发生,改善了飞机的失速特性。     

基于ANSYS Workbench鸟撞飞机风挡有限元分析

利用ANSYS Workbench三维有限元软件,建立了鸟撞飞机风挡的力学分析模型,形成了一套完整合理的鸟撞飞机动态响应分析方法。其中,对模型建立和约束施加等提出了简便的处理方法,并且进行了比较详细的描述。通过有限元分析模拟计算鸟撞飞机前风挡的动态响应,得出了风挡的应力、位移及其分布规律,并与试验结果进行比较,两者吻合较好,可为新型风挡结构设计提供参考。