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18 pages, 5601 KiB

Open AccessArticle

Active Control of Shimmy in Articulated Single-Axle Straddle-Type Monorail Train

by Jiachen Song, Liwei Zhang, Dongjin Zhu and Hui Liang

Machines 2024, 12(12), 854; https://doi.org/10.3390/machines12120854 - 26 Nov 2024

Cited by 1 | Viewed by 910

The articulated single-axle straddle-type monorail train has many unique advantages, making it the preferred choice for medium-capacity urban rail transit. However, the issue of vehicle shimmy greatly restricts its promotion and application. In response to this issue, an active suspension control scheme is [...] Read more.

The articulated single-axle straddle-type monorail train has many unique advantages, making it the preferred choice for medium-capacity urban rail transit. However, the issue of vehicle shimmy greatly restricts its promotion and application. In response to this issue, an active suspension control scheme is proposed, and the corresponding control algorithm is designed. Considering economic and feasible factors, a modification plan for the single-axle bogie without changing the original structure is proposed. A closed-loop feedback control strategy with lateral velocity and yaw rate as control objectives is designed, and a 114 degree-of-freedom dynamic model of a monorail train is established. Taking the skyhook damping control as the reference model, the SH-SMC (skyhook-sliding mode control) active control scheme is designed based on the sliding mode control theory. Considering practical applications, the control force distribution algorithm is further proposed. Through co-simulation of UM and Matlab, different control schemes are compared and analyzed. The results indicate that the SH-SMC active control scheme is more effective in suppressing the shimmy of single-axle monorail train, verifying the effectiveness of the SH-SMC active control scheme. It is of great significance for the further promotion and application of single-axle monorail trains in more cities. Full article

(This article belongs to the Special Issue Intelligent Control and Active Safety Techniques for Road Vehicles)

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25 pages, 1404 KiB

Open AccessArticle

An Integrated Lagrangian Modeling Method for Mechanical Systems with Memory Elements

by Jia-Mei Nie, Xiang-Bo Liu and Xiao-Liang Zhang

Machines 2024, 12(3), 208; https://doi.org/10.3390/machines12030208 - 20 Mar 2024

Viewed by 1845

Abstract

Mechanical memory elements cannot be accurately modeled using the Lagrangian method in the classical sense, since these elements are nonconservative in the plane of their non-constitutive relationships, and the system differential equations are not self-adjoint and therefore do not allow a Lagrangian formulation. [...] Read more.

Mechanical memory elements cannot be accurately modeled using the Lagrangian method in the classical sense, since these elements are nonconservative in the plane of their non-constitutive relationships, and the system differential equations are not self-adjoint and therefore do not allow a Lagrangian formulation. To overcome this problem, the integrated Lagrangian modeling method is introduced, in which the associated conventional energies in the system are replaced by the corresponding memory state functions of the memory elements. An example, a vehicle shimmy system equipped with fluid mem-inerters, is presented to verify the improvement of modeling accuracy of mechanical systems with memory elements via the integrated Lagrangian method. The simulation results show that under pulse and random excitation, using the Lagrangian method to model the system, the values of system response indicators exhibit significant errors ranging from

5.17 %

to

24.54 %

compared with the values obtained by the integrated Lagrangian method, namely, the accurate values. In addition, the influencing factors of the error and are discussed and the fractional-order memory elements and their modeling are also briefly generalized. Full article

(This article belongs to the Section Machine Design and Theory)

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20 pages, 6966 KiB

Open AccessArticle

Research on the Stability and Bifurcation Characteristics of a Landing Gear Shimming Dynamics System

by Shuang Ruan, Ming Zhang, Shaofei Yang, Xiaohang Hu and Hong Nie

Aerospace 2024, 11(2), 104; https://doi.org/10.3390/aerospace11020104 - 23 Jan 2024

Cited by 2 | Viewed by 1920

Abstract

A dynamic model is established to investigate the shimmy instability of a landing gear system, considering the influence of nonlinear damping. The stability criterion is utilized to determine the critical speed at which the landing gear system becomes unstable. The central manifold theorem [...] Read more.

A dynamic model is established to investigate the shimmy instability of a landing gear system, considering the influence of nonlinear damping. The stability criterion is utilized to determine the critical speed at which the landing gear system becomes unstable. The central manifold theorem and canonical method are employed to simplify the dynamic model of the landing gear. The first Lyapunov coefficient of the system is theoretically derived and verified using numerical simulation. Further investigation on the Hopf bifurcation characteristics and stability of the shimmy in the landing gear system is conducted. The results indicate that above a certain threshold speed, with a tire stability distance greater than half the tire length in contact with the ground plus the slack length, the aircraft remains stable during taxiing. At critical speeds, a shimmy system with higher-order nonlinear damping will undergo supercritical Hopf bifurcation. Quantitative analysis suggests an increase in the linear damping coefficient within a range that ensures a stability margin to mitigate undesired oscillation, while the nonlinear damping coefficient should be designed within a reasonable range to decrease the amplitude of the limit cycle. Full article

(This article belongs to the Special Issue Landing System Design in Aerospace)

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16 pages, 5767 KiB

Open AccessArticle

Effect of Multi-Joint Clearance Coupling on Shimmy of Nose Landing Gear

by Guang Feng, Bingyan Jiang and Yiyao Jiang

Aerospace 2023, 10(11), 911; https://doi.org/10.3390/aerospace10110911 - 25 Oct 2023

Cited by 3 | Viewed by 3332

Abstract

The existence of joint clearances in the nose landing gear (NLG) is inevitable and significantly affects shimmy. It was found that the interaction of each joint clearance is closely related to the analysis of shimmy stability. In this study, the shimmy model of [...] Read more.

The existence of joint clearances in the nose landing gear (NLG) is inevitable and significantly affects shimmy. It was found that the interaction of each joint clearance is closely related to the analysis of shimmy stability. In this study, the shimmy model of NLG with three-dimensional joint clearance was established by using LMS VirtualLab Motion. Based on the method of multibody dynamics (MBD), the load transfer mechanism at the joints of the NLG was analyzed, and the oscillation characteristics with multiple joint clearances were investigated. The results indicate that the radial and axial contact force of the joint decreases from bottom to top, and the radial contact forces are relatively high at the end positions of the connection shafts, resulting in uneven wear. When the joint clearance reaches a certain value, periodic shimmy of the NLG will occur, and an increase in torsional damping can reduce the amplitude of the shimmy. Therefore, this study reveals the influence of multi-position joint clearance coupling on shimmy, and provides a valuable insight for the maintenance and design of landing gear joints. Full article

(This article belongs to the Special Issue Structural Dynamics and Control (2nd Edition))

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17 pages, 4800 KiB

Open AccessArticle

Evaluation of Joint Clearance Effects on the Shimmy of Nose Landing Gear

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

Aerospace 2023, 10(8), 722; https://doi.org/10.3390/aerospace10080722 - 17 Aug 2023

Cited by 7 | Viewed by 4222

Abstract

Through the establishment of a three-dimensional joint clearance model, the effects of joint clearances at different positions on shimmy stability are evaluated. In this paper, considering the radial, axial and coupling characteristics of joint clearance, the shimmy multibody dynamics (MBD) model is applied [...] Read more.

Through the establishment of a three-dimensional joint clearance model, the effects of joint clearances at different positions on shimmy stability are evaluated. In this paper, considering the radial, axial and coupling characteristics of joint clearance, the shimmy multibody dynamics (MBD) model is applied to different joints in the nose landing gear (NLG) transmission system. It is proposed to evaluate the influence of joint clearance on shimmy from two aspects of position factor and wear factor. The study found that different joint clearances have different effects on shimmy: the joint clearance between the NLG and fuselage has little influence on shimmy; the larger axial clearance of upper and lower torque link joint will cause the shimmy of the NLG, but the radial clearance has no effect on shimmy; while the joint clearance between turning sleeve and upper torque link, lower torque link and piston only works in the axial and radial coupling. The reasons for the different influence characteristics of each joint space are analyzed. Consequently, studying and summarizing the influence of different clearance on shimmy is of great significance for the design and maintenance of the NLG joints. Full article

(This article belongs to the Special Issue Structural Dynamics and Control (2nd Edition))

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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 11 | Viewed by 5197

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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16 pages, 6005 KiB

Open AccessArticle

Predicting the Remaining Useful Life of Landing Gear with Prognostics and Health Management (PHM)

by Tzu-Hsuan Hsu, Yuan-Jen Chang, He-Kai Hsu, Tsung-Ti Chen and Po-Wen Hwang

Aerospace 2022, 9(8), 462; https://doi.org/10.3390/aerospace9080462 - 20 Aug 2022

Cited by 28 | Viewed by 14105

Abstract

Landing gear is an essential part of an aircraft. However, the components of landing gear are susceptible to degradation over the life of their operation, which can result in the shimmy effect occurring during take-off and landing. In order to reduce unplanned flight [...] Read more.

Landing gear is an essential part of an aircraft. However, the components of landing gear are susceptible to degradation over the life of their operation, which can result in the shimmy effect occurring during take-off and landing. In order to reduce unplanned flight disruptions and increase the availability of aircraft, the predictive maintenance (PdM) technique is investigated in this study. This paper presents a case study on the implementation of a health assessment and prediction workflow for remaining useful life (RUL) based on the prognostics and health management (PHM) framework of currently in-service aircraft, which could significantly benefit fleet operators and aircraft maintenance. Machine learning is utilized to develop a health indicator (HI) for landing gear using a data-driven approach, whereas a time-series analysis (TSA) is used to predict its degradation. The degradation models are evaluated using large volumes of real sensor data from in-service aircraft. Finally, the challenges of implementing a built-in PHM system for next-generation aircraft are outlined. Full article

(This article belongs to the Special Issue Recent Advances in Computational Mechanics)

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21 pages, 10509 KiB

Open AccessArticle

Design and Simulation Analysis of an Electromagnetic Damper for Reducing Shimmy in Electrically Actuated Nose Wheel Steering Systems

by Chenfei She, Ming Zhang, Yibo Ge, Liming Tang, Haifeng Yin and Gang Peng

Aerospace 2022, 9(2), 113; https://doi.org/10.3390/aerospace9020113 - 19 Feb 2022

Cited by 8 | Viewed by 4307

Abstract

Based on the technical platform of electrically actuated nose wheel steering systems, a new type of damping shimmy reduction technology is developed to break through the limitations of traditional hydraulic damping shimmy reduction methods, and an electrically actuated nose wheel steering structure scheme [...] Read more.

Based on the technical platform of electrically actuated nose wheel steering systems, a new type of damping shimmy reduction technology is developed to break through the limitations of traditional hydraulic damping shimmy reduction methods, and an electrically actuated nose wheel steering structure scheme is proposed. The mathematical model of the electromagnetic damper is established, the derivation of skin depth, damping torque and damping coefficient is completed, and the design of the shape and size of the electromagnetic damper is combined with the derivation results and the technical index of shimmy reduction. The electromagnetic field finite element simulation results show that the mathematical modeling method of the electromagnetic damper has good accuracy, and its application to the shimmy reduction module of the electrically actuated nose wheel steering system is also feasible and superior. Finally, the key factors influencing the performance of electromagnetic damper shimmy reduction are studied and analyzed, thus forming a complete electromagnetic damper shimmy reduction technology for the electrically actuated system, and laying the foundation for the design of novel all-electric aircraft and landing gear. Full article

(This article belongs to the Special Issue Electro-Mechanical Actuators for Safety-Critical Aerospace Applications)

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17 pages, 5909 KiB

Open AccessArticle

Analysis of the Effect of Mass Parameters on Motorcycle Vibration and Stability

by Andrzej Dębowski

Energies 2021, 14(16), 5090; https://doi.org/10.3390/en14165090 - 18 Aug 2021

Cited by 8 | Viewed by 4081

Abstract

This paper presents a vibration analysis method and an example of its application to evaluate the influence of mass parameters on torsional vibration frequencies in the steering system of a motorcycle. The purpose of this paper is to analyze to what extent vibration [...] Read more.

This paper presents a vibration analysis method and an example of its application to evaluate the influence of mass parameters on torsional vibration frequencies in the steering system of a motorcycle. The purpose of this paper is to analyze to what extent vibration frequencies can change during their daily operation. These changes are largely due to the ratio of vehicle weight to driver and load. The complex dynamics make it very difficult to conduct research using simple models. It is difficult to observe the influence of individual parameters because they are strongly interrelated. This paper provides a description of the vibration analysis method, and the results are presented in the form of Bode diagrams and tables. On this basis, it was found that the driver, deciding on the way of using the vehicle and introducing modifications in it, influences the resonant frequencies of the steering system. Typical exploitation factors, on the other hand, do not cause significant changes, although they may contribute to increasing the sensitivity of the system to vibrations. The conducted analysis also showed some nonlinear changes in the dynamics of the system with linear changes of the parameter values. Full article

(This article belongs to the Special Issue Vehicle and Traffic Safety)

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