Aerospace

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24 pages, 5164 KiB

Open AccessArticle

Space-Time Finite Element Method for Fully Intrinsic Equations of Geometrically Exact Beam

by Lidao Chen, Xin Hu and Yong Liu

Aerospace 2023, 10(2), 92; https://doi.org/10.3390/aerospace10020092 - 17 Jan 2023

Cited by 1 | Viewed by 1925

In this paper, a space-time finite element method based on a Galerkin-weighted residual method is proposed to solve the nonlinear fully intrinsic equations of geometrically exact beam which are first-order partial differential equations about time and space. Therefore, it is natural to discretize [...] Read more.

In this paper, a space-time finite element method based on a Galerkin-weighted residual method is proposed to solve the nonlinear fully intrinsic equations of geometrically exact beam which are first-order partial differential equations about time and space. Therefore, it is natural to discretize it in time and space simultaneously. Considering the continuity and intrinsic boundary conditions in the spatial direction and the continuity and periodic boundary conditions in the time direction, the boundary value scheme of space-time finite element for solving the full intrinsic equations is derived. This method has been successfully applied to the static analysis and dynamic response solution of the fully intrinsic equations of nonlinear geometrically exact beam. The numerical results of several examples are compared with the analytical solution, existing algorithms, and literature to illustrate the applicability, accuracy and efficiency of this method. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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20 pages, 5609 KiB

Open AccessArticle

A Homogenization Method for Replacement Stator Models in an Aero-Engine

by Wenjun Wang, Yu Fan, Lin Li, Yuning Zhang and Zhiqiang Song

Aerospace 2022, 9(12), 837; https://doi.org/10.3390/aerospace9120837 - 16 Dec 2022

Viewed by 1462

Abstract

Generally, the high-fidelity finite element models of aero-engines comprise millions of degrees of freedom (DOFs). Although they can provide precise predictions of structural dynamics, the computational cost will be often unaffordable if appropriate dimension reduction techniques are not adopted. The homogenization of the [...] Read more.

Generally, the high-fidelity finite element models of aero-engines comprise millions of degrees of freedom (DOFs). Although they can provide precise predictions of structural dynamics, the computational cost will be often unaffordable if appropriate dimension reduction techniques are not adopted. The homogenization of the substructure, also termed as the physical replacement, reduces the model scale by simplifying the unnecessary details of the substructure, thus speeding up the dynamic analysis of the whole engine. In this study, we design the physical replacements for the stators of an aero-engine based on the long-wave assumption. These replacements have the same wave features as the stators in long-wave cases while possessing fewer DOFs. The core steps include the analytical description of the stators and the corresponding physical replacement design through two homogenizations. Specifically, we first investigate the wave characteristics of the stators using the wave finite element method and find two dominant waves: flexural and flexural–torsional coupled waves. The first homogenization introduces two analytical Timoshenko beams to describe the two wave motions of the stators. These two analytical beams are subsequently solidified into physical replacements with I, box, and open cross-sections in the second homogenization. The mechanical and geometric parameters are identified through a combination of the static analysis and the genetic algorithm (GA). The search processes are of great efficiency, because all the descriptions are analytical. Results show that the relative errors of the natural frequencies between the pristine stators and the physical replacements associated with the nodal diameters 6–15 are less than 5%. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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20 pages, 670 KiB

Open AccessArticle

Active Flutter Suppression of a Wing Section in a Compressible Flow

by Álvaro Muñoz and Pablo García-Fogeda

Aerospace 2022, 9(12), 804; https://doi.org/10.3390/aerospace9120804 - 7 Dec 2022

Cited by 4 | Viewed by 1548

Abstract

In this paper, a unified method for the computation of the unsteady aerodynamic forces in the Laplace domain for a wing section in subsonic, sonic and supersonic potential flows is presented. The subsonic solution is a new development based on the pressure mode [...] Read more.

In this paper, a unified method for the computation of the unsteady aerodynamic forces in the Laplace domain for a wing section in subsonic, sonic and supersonic potential flows is presented. The subsonic solution is a new development based on the pressure mode method. The unsteady aerodynamic forces are evaluated in the Laplace domain by an efficient method for computing the kernel. The sonic potential flow solution is an extension of the solution for the frequency domain to the Laplace domain. Analytical expressions for the unsteady pressure coefficient and the unsteady aerodynamic forces in the Laplace domain are obtained for this flow regime. The method is validated in these regimes with existing theories in the frequency domain, and its application to flutter computation is provided for different Mach numbers by the use of the p-method. Active flutter suppression for a wing section with three degrees of freedom has been studied, and an adequate control law has been obtained. Using the proposed approach allows to calculate the unsteady aerodynamic forces directly in the Laplace domain, avoiding the inconvenience of the curve fitting from the frequency to the Laplace domain. In particular, this work can be used as a base for the application of other procedures for flutter suppression in the transonic regime. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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19 pages, 5643 KiB

Open AccessArticle

Nonlinear Dynamics of a Space Tensioned Membrane Antenna during Orbital Maneuvering

by Yifan Lu, Qi Shao, Liangliang Lv, Guangqiang Fang and Honghao Yue

Aerospace 2022, 9(12), 794; https://doi.org/10.3390/aerospace9120794 - 4 Dec 2022

Cited by 8 | Viewed by 1620

Abstract

Due to the super flexibility and strong nonlinearity of space membrane antennas, the dynamic response of a space membrane antenna will be affected by the rigid–flexible coupling effect in the process of orbital maneuvering. In this case, the dynamic model of a tensioned [...] Read more.

Due to the super flexibility and strong nonlinearity of space membrane antennas, the dynamic response of a space membrane antenna will be affected by the rigid–flexible coupling effect in the process of orbital maneuvering. In this case, the dynamic model of a tensioned membrane antenna is significantly different from that under the general condition (fixed boundary). In this study, a nonlinear dynamic model of a tensioned space membrane antenna experiencing maneuvering is established, and the influence of the rigid–flexible coupling effect on structural stiffness and damping characteristics is described. Through a numerical solution, the effects of rigid body motion and structural natural frequency on the rigid–flexible coupling effect are discussed. The results show that the vibration frequency and amplitude of the antenna are positively correlated with the acceleration and initial velocity of rigid body motion. With the increase of the natural frequency of the antenna, the vibration frequency increases but the amplitude decreases. The rigid–flexible coupling nonlinear dynamic model proposed in this work is more applicable in intelligent vibration control compared to finite element software. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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25 pages, 10919 KiB

Open AccessArticle

Fluid–Structure Interaction Dynamic Response of Rocket Fairing in Falling Phase

by Zexuan Yang, Chao Yang, Jiamin Zhao and Zhigang Wu

Aerospace 2022, 9(12), 741; https://doi.org/10.3390/aerospace9120741 - 23 Nov 2022

Cited by 2 | Viewed by 2028

Abstract

A method based on fluid–structure coupling is used in this study to calculate the response of a rocket fairing as it is falling. Some cases of vibration divergence of the fairing were found, and the influence of some specific factors was analyzed. The [...] Read more.

A method based on fluid–structure coupling is used in this study to calculate the response of a rocket fairing as it is falling. Some cases of vibration divergence of the fairing were found, and the influence of some specific factors was analyzed. The aerodynamic forces are calculated by using computational fluid dynamics (CFD) software and the structural responses by the modal-superposition method. The data are then subjected to modal interpolation in the CFD solver for the next cycle of calculation. The dynamic pressure, Mach number, and angle of attack are fixed in this process. Given that the fairing has a fixed attitude during falling, its rotation is ignored in calculations for the simulation. The results are then used to propose a framework for the fluid–structure coupling-based analysis of a non-streamlined structure. The mechanism of the fairing is discussed based on this method, and the effects of the settings of the solver, Mach number, dynamic pressure, and structural stiffness on it are investigated. Dangerous and safe regions are identified as the fairing falls back to the ground. Three methods are then provided based on the above analysis to prevent damage to the fairing as it falls to ground, such as increasing structure rigidity, attitude control, and opening the parachute at high altitude. A comprehensive method was used to suppress the vibration of the fairing during the descent, which was proven to be effective. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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13 pages, 4207 KiB

Open AccessArticle

Influence of Nose Landing Gear Torsional Damping on the Stability of Aircraft Taxiing Direction

by Yiyao Jiang, Guang Feng, Panglun Liu, Li Yuan, Jianbin Ding and Bingyan Jiang

Aerospace 2022, 9(11), 729; https://doi.org/10.3390/aerospace9110729 - 19 Nov 2022

Cited by 9 | Viewed by 4281

Abstract

The design of the nose landing gear (NLG) torsional damping is very important to avoid the taxiing vibration of the aircraft. On the one hand, increasing the torsional damping can suppress the nose wheel shimmy. On the other hand, if the design value [...] Read more.

The design of the nose landing gear (NLG) torsional damping is very important to avoid the taxiing vibration of the aircraft. On the one hand, increasing the torsional damping can suppress the nose wheel shimmy. On the other hand, if the design value is too large, it will cause unstable vibration of the aircraft direction, and the latter will often be ignored, which will bring potential risks to the taxiing safety of the aircraft. In this paper, by establishing a multibody dynamics model (MBD) of aircraft taxiing, including NLG, main landing gear (MLG), airframe, related force elements and kinematic pairs, the effect of the torsional damping of NLG on aircraft directional stability is studied, and the key taxiing parameters of aircraft taxiing in an unstable direction are obtained. In order to propose the damping design specification for the nose landing gear anti-shimmy system, the critical value of torsional damping for stable taxiing in the direction of the aircraft is calculated. It is found that nose wheel shimmy and the unstable vibration of the aircraft direction will occur simultaneously, but the vibration frequencies are different. Therefore, in addition to the anti-shimmy design, the influence of the aircraft’s directional unstable vibration must also be considered in the engineering application. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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Graphical abstract

19 pages, 3070 KiB

Open AccessArticle

Differential Quadrature Method for Fully Intrinsic Equations of Geometrically Exact Beams

by Lidao Chen and Yong Liu

Aerospace 2022, 9(10), 596; https://doi.org/10.3390/aerospace9100596 - 12 Oct 2022

Cited by 2 | Viewed by 1780

Abstract

In this paper, a differential quadrature method of high-order precision (DQ−Pade), which is equivalent to the generalized Pade approximation for approximating the end of a time or spatial interval, is used to solve nonlinear fully intrinsic equations of beams. The equations are a [...] Read more.

In this paper, a differential quadrature method of high-order precision (DQ−Pade), which is equivalent to the generalized Pade approximation for approximating the end of a time or spatial interval, is used to solve nonlinear fully intrinsic equations of beams. The equations are a set of first-order differential equations with respect to time and space, and the explicit unknowns of the equations involve only forces, moments, velocity and angular velocity, without displacements and rotations. Based on the DQ−Pade method, the spatial and temporal discrete forms of fully intrinsic equations were derived. To verify the effectiveness and applicability of the proposed method for discretizing the fully intrinsic equations, different examples available in the literatures were considered. It was found that when using the DQ−Pade method, the solutions of the intrinsic beam equations are obviously superior to those found by some other usual algorithms in efficiency and computational accuracy. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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26 pages, 4970 KiB

Open AccessArticle

Free Vibration Analysis of a Reconfigurable Modular Morphing Wing

by Faisal Mahmood, Seyed M. Hashemi and Hekmat Alighanbari

Aerospace 2022, 9(10), 532; https://doi.org/10.3390/aerospace9100532 - 21 Sep 2022

Cited by 2 | Viewed by 2250

Abstract

Aircraft experience various phases during each flight. Optimal performance, without compromise, during various phases can be achieved through adaptability in the wing design. Morphing wing design encompasses most, if not all, the flight conditions variations, and can respond interactively. In the present work, [...] Read more.

Aircraft experience various phases during each flight. Optimal performance, without compromise, during various phases can be achieved through adaptability in the wing design. Morphing wing design encompasses most, if not all, the flight conditions variations, and can respond interactively. In the present work, the dynamic characteristics of a reconfigurable modular morphing wing of two topological architectures, developed in-house by a research group at Toronto Metropolitan University (formerly Ryerso University), were investigated. This modular morphing wing, developed based on the idea of a parallel robot, consists of a number of structural elements connected to each other and to the wing ribs through eye-bolt joints. Euler–Bernoulli and Timoshenko bending beam theories, in conjunction with Finite Element Analysis, were exploited. Free vibration of unmorphed (Original) and morphed configurations subjected to spanwise extensions were studied. The results of systems’ free vibration analyses were validated against those obtained from Ansys and Dynamic Stiffness Matrix (DSM) method. The effect of various spanwise extensions, as well as topology on system’s natural frequencies, was also studied and reported on. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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13 pages, 1817 KiB

Open AccessArticle

Design of a Maglev Stewart Platform for the Microgravity Vibration Isolation

by He Ma, Weichao Chi, Caihua Wang and Jia Luo

Aerospace 2022, 9(9), 514; https://doi.org/10.3390/aerospace9090514 - 15 Sep 2022

Cited by 7 | Viewed by 2150

Abstract

Vibration isolation mechanisms are usually installed on spacecraft between the vibration sources and the payload to ensure that precision instruments work properly. This paper proposes a novel maglev Stewart platform for vibration isolation in a microgravity environment. The maglev Stewart platform combines the [...] Read more.

Vibration isolation mechanisms are usually installed on spacecraft between the vibration sources and the payload to ensure that precision instruments work properly. This paper proposes a novel maglev Stewart platform for vibration isolation in a microgravity environment. The maglev Stewart platform combines the quasi-zero stiffness of maglev actuators and the high maneuverability of the Stewart platform. The dynamic of the legs and the payload platform is analyzed, and the linear active disturbance rejection control (LADRC) algorithm is used to decouple the legs and cancel the total disturbance in the linear feedback. The simulation studies show that with the maglev Stewart platform, there is no longer any obvious resonance. The transmission ratio of vibration can be reduced significantly compared with the traditional elastic Stewart platform. Last but not least, the influence of two control parameters on vibration isolation performance is connected to certain physical meaning of the vibration problem. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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19 pages, 3552 KiB

Open AccessArticle

Discrete-Time Model Predictive Controller Using Laguerre Functions for Active Flutter Suppression of a 2D wing with a Flap

by Tariq Darabseh, Abdallah Tarabulsi and Abdel-Hamid I. Mourad

Aerospace 2022, 9(9), 475; https://doi.org/10.3390/aerospace9090475 - 27 Aug 2022

Cited by 3 | Viewed by 2133

Abstract

In this paper, a discrete-time model predictive controller using Laguerre orthonormal function-based (LMPC) for active flutter suppression of a two-dimensional wing with a flap is presented. In this work, a linear mathematical state-space model for the pitch, plunge, and flap degrees of freedom [...] Read more.

In this paper, a discrete-time model predictive controller using Laguerre orthonormal function-based (LMPC) for active flutter suppression of a two-dimensional wing with a flap is presented. In this work, a linear mathematical state-space model for the pitch, plunge, and flap degrees of freedom under unsteady aerodynamics is derived and used to determine the linear flutter velocity and frequency of the parameters of a selected experimental wing. To verify the model, the open-loop simulation results are compared to an experimental study using the same wing from the literature. The state-space system is then discretized and LMPC with a Kalman filter is designed and tuned using the MATLAB^® simulation environment at a selected speed in the linear flutter region. The predictive control advantage of dealing with input constraints in a systematic manner is explored through a quantitative analysis of the response of both constrained and unconstrained LMPC controllers. The results indicate that theoretically both cases can give excellent performance. However, the input trajectory generated by the unconstrained LMPC is very aggressive in a way that it is considered impractical when compared to the physical limits of an experimental actuator from the literature. The potential of LMPC to achieve a reasonable performance at a significantly lower computational cost compared to the classical model predictive controller (MPC) is investigated by measuring the time required by the same computer to compute the control trajectory for both controllers. The data suggest that LMPC requires remarkably low computational power, which makes it an excellent choice for fast aeroelastic applications. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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20 pages, 46904 KiB

Open AccessArticle

Ground Vibration Testing of a Flexible Wing: A Benchmark and Case Study

by Gabriele Dessena, Dmitry I. Ignatyev, James F. Whidborne, Alessandro Pontillo and Luca Zanotti Fragonara

Aerospace 2022, 9(8), 438; https://doi.org/10.3390/aerospace9080438 - 10 Aug 2022

Cited by 10 | Viewed by 3742

Abstract

Beam-like flexible structures are of interest in many fields of engineering, particularly aeronautics, where wings are frequently modelled and represented as such. Experimental modal analysis is commonly used to characterise the wing’s dynamical response. However, unlike other flexible structure applications, no benchmark problems [...] Read more.

Beam-like flexible structures are of interest in many fields of engineering, particularly aeronautics, where wings are frequently modelled and represented as such. Experimental modal analysis is commonly used to characterise the wing’s dynamical response. However, unlike other flexible structure applications, no benchmark problems involving high-aspect-ratio flexible wings have appeared in the open literature. To address this, this paper reports on ground vibration testing results for a flexible wing and its sub-assembly and parts. The experimental data can be used as a benchmark and are available to the aeronautical and structural dynamics community. Furthermore, non-linearities in the structure, where present, were detected. Tests were performed on the whole wing as well as parts and sub-assembly, providing four specimens. These were excited with random vibration at three different amplitudes from a shaker table. The modal properties of a very flexible high-aspect-ratio wing model, its sub-assembly and parts, were extracted, non-linear behaviour was detected and the experimental data are shared in an open repository. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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18 pages, 6439 KiB

Open AccessArticle

Impact Load Identification Algorithm of Helicopter Weapon Pylon Based on Time-Domain Response Signal

by Yadong Gao, Xinyu Yu, Likun Chen and Dawei Huang

Aerospace 2022, 9(7), 388; https://doi.org/10.3390/aerospace9070388 - 18 Jul 2022

Cited by 2 | Viewed by 2014

Abstract

Accurately identifying the peak value of impact load acting on the helicopter structure during weapon launch is of great significance to the design and finalization of weapon pylons. Firstly, a method of standardized preprocessing load signal is proposed by analyzing the vibration response [...] Read more.

Accurately identifying the peak value of impact load acting on the helicopter structure during weapon launch is of great significance to the design and finalization of weapon pylons. Firstly, a method of standardized preprocessing load signal is proposed by analyzing the vibration response and the characteristics of the impact load. Then, the test model of the weapon pylon is designed, and the position of the strain gauge is determined; the static load calibration test and the ground impact test are carried out on the test model. Next, the time-domain response measured by the strain gauge is filtered and de-noised. Impact load is processed by a standardized method. The response and load are used to train BP neural network and the mapping relationship between response and load is established. The impact load generated by a specific weapon is statistically processed to obtain the normalized average load time history, and the identified standard load is converted back to the original load pattern. Finally, the network that meets the error requirements is tested. Both the standardized pattern and the original pattern have high identification accuracy, which shows that an effective load identification model can be established based on the time-domain response signal and the standardized processed load signal. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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18 pages, 4004 KiB

Open AccessArticle

Structural Damage Assessment Using Multiple-Stage Dynamic Flexibility Analysis

by Yun Sun , Qiuwei Yang and Xi Peng

Aerospace 2022, 9(6), 295; https://doi.org/10.3390/aerospace9060295 - 29 May 2022

Cited by 4 | Viewed by 2168

Abstract

Vibration-based damage assessment technology is a hot topic in aerospace engineering, civil engineering, and mechanical engineering. In this paper, a damage assessment approach using multiple-stage dynamic flexibility analysis is proposed for structural safety monitoring. The proposed method consists of three stages. The content [...] Read more.

Vibration-based damage assessment technology is a hot topic in aerospace engineering, civil engineering, and mechanical engineering. In this paper, a damage assessment approach using multiple-stage dynamic flexibility analysis is proposed for structural safety monitoring. The proposed method consists of three stages. The content of Stage I is to determine the number of damaged elements in the structure by the rank of dynamic flexibility change. The content of Stage II is to determine damage locations by the minimum rank of flexibility correlation matrices. Finally, the damage extents of those damaged elements are calculated in Stage III. The proposed approach fully uses the filtering ability of matrix rank analysis for data noise. A 27-bar truss structure and a steel frame structure are used as the numerical and experimental examples to demonstrate the proposed method, respectively. From the numerical and experimental results, it is found that structure damages can be successfully identified through the multiple-stage dynamic flexibility analysis. By comparative study, the proposed method has more powerful antinoise ability and higher calculation accuracy than the generalized flexibility method. The proposed method may be a promising tool for structural damage assessment. Full article

(This article belongs to the Special Issue Structural Dynamics and Control)

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