Dynamics Analysis of Spatial Landing-Gear Mechanism with Hinge Clearance and Axis Deviation

Yin, Yin; Xu, Kui; Nie, Hong; Wei, Xiaohui; Wang, Huilong

doi:10.2514/1.c035739

Cited by 7 publications

(14 citation statements)

References 26 publications

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“…The shimmy damper and the strut's torsional stiffness are connected in parallel, and the parallel stiffness is then connected in series with the sliding tube's torsional stiffness. Equation (2)(3)(4)(5)(6)(7)(8)(9)(10)(11) displays the analogous relationship between the torsional damping of the two models. The sliding tube damping, the shimmy damper damping, and the main fitting damping are coupled in series.…”

Section: Mathematical Modeling Of Three Torsional Degrees Of Freedom ...mentioning

confidence: 99%

Influence of structural torsional degree of freedom on nose landing gear shimmy

Ding,

Feng,

Liu

et al. 2023

Preprint

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The structural characteristic of combining a maneuvering mechanism and a shimmy damper into a single component is present in the nose landing gear of large civil aircraft. Establishing a more accurate shimmy model based on this property is crucial. The three torsional degrees of freedom shimmy of the nose landing gear was mathematically and physically modeled. The time domain curve, spectrum diagram, and bifurcation diagram were used to compare the three torsional degrees of freedom shimmy model and the single torsional degrees of freedom shimmy model. The three-torsional freedom model predicts a greater amplitude and a longer convergence time in comparison to the findings of the single-torsional freedom model. The sliding tube's torsional vibration frequency falls from 10.9Hz to 8.1Hz in the three-torsional degree-of-freedom model, while the structure's lateral vibration frequency stays the same. The three-torsional freedom model predicts a decrease in the region of stable and torsional shimmy and an increase in the area of lateral and quasi-periodic shimmy. The amplitudes of all degrees of freedom in the three torsional degrees of freedom model, regardless of whether it is torsional or lateral, are greater than those in the single torsional degrees of freedom model when the vertical load is fixed. By increasing the torsional degrees of freedom of the shimmy damper and the main fitting, the inertia, stiffness, and damping in the torsional direction are redistributed in the three-torsional shimmy vibration model, which reduces the stability of the system.

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Section: Mathematical Modeling Of Three Torsional Degrees Of Freedom ...mentioning

confidence: 99%

Influence of structural torsional degree of freedom on nose landing gear shimmy

Ding,

Feng,

Liu

et al. 2023

Preprint

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“…3 Uplocked landing gear showing spring placement, unlock force and retraction moment; here L 1 is the shock strut, L 2 and L 3 are the sidestay links, and L 4 and L 5 are the locklinks with respect to a global co-ordinate system, and connected to one another by planar rotational joints. Previous work on landing gear mechanisms formulated the model as a set of algebraic equations to describe the mechanism's equilibrium position in response to externally applied forces [27,29,30,32]. Coetzee developed an approach that enables numerical continuation to be applied directly to mechanism models created in multibody dynamics software packages-a key enabler for their uptake within engineering industrial practice.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Numerical continuation methods have to date been used to analyse conventional landing gear mechanisms [27][28][29][30] as well as some non-conventional ones with multiple sidestays [31,32] or single lock mechanisms [33,34]. In all cases, ensuring that the landing gear can be locked is critical to demonstrate its functionalityyet difficulties have been identified with both multiple side stay and single lock mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…In all cases, ensuring that the landing gear can be locked is critical to demonstrate its functionalityyet difficulties have been identified with both multiple side stay and single lock mechanisms. Current research has identified that fold bifurcations of steady states play an important role in separating these locked and unlocked positions [32,33]. Some of these key bifurcations persist under parameter changes or variations in external loading conditions, whilst others do not [34].…”

Section: Introductionmentioning

confidence: 99%

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Unlocking a nose landing gear in different flight conditions: folds, cusps and a swallowtail

2021

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This paper investigates the unlocking of a non-conventional nose landing gear mechanism that uses a single lock to fix the landing gear in both its downlocked and uplocked states (as opposed to having two separate locks as in most present nose landing gears in operation today). More specifically, we present a bifurcation analysis of a parameterized mathematical model for this mechanical system that features elastic constraints and takes into account internal and external forces. This formulation makes it possible to employ numerical continuation techniques to determine the robustness of the proposed unlocking strategy with respect to changing aircraft attitude. In this way, we identify as a function of several parameters the steady-state solutions of the system, as well as their bifurcations: fold bifurcations where two steady states coalesce, cusp points on curves of fold bifurcations, and a swallowtail bifurcation that generates two cusp points. Our results are presented as surfaces of steady states, joined by curves of fold bifurcations, over the plane of retraction actuator force and unlock actuator force, where we consider four scenarios of the aircraft: level flight; steep climb; steep descent; intermediate descent. A crucial cusp point is found to exist irrespective of aircraft attitude: it corresponds to the mechanism being at overcentre, which is a position that creates a mechanical singularity with respect to the effect of forces applied by the actuators. Furthermore, two cusps on a key fold locus are unfolded in a (codimension-three) swallowtail bifurcation as the aircraft attitude is changed: physical factors that create these bifurcations are presented. A practical outcome of this research is the realization that the design of this and other types of landing gear mechanism should be undertaken by considering the effects of forces over considerable ranges, with a special focus on the overcentre position, to ensure a smooth retraction occurs. More generally, continuation methods are shown to be a valuable tool for determining the overall geometric structure of steady states of mechanisms subject to (external) forces.

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“…Filipe Marques [23] proposed a new formula to simulate the spatial joints with radial and axial clearances; Yan et al [24] considered the radial and axial clearances between the rotating shaft and the shaft sleeve, and based on the analysis of the geometric characteristics of the motion pair, 13 contact modes and their conditions were given. In addition, the influence characteristics of different joint clearances are different [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

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

Jiang,

Feng,

Liu

et al. 2023

Aerospace

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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.

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Dynamics Analysis of Spatial Landing-Gear Mechanism with Hinge Clearance and Axis Deviation

Cited by 7 publications

References 26 publications

Influence of structural torsional degree of freedom on nose landing gear shimmy

Influence of structural torsional degree of freedom on nose landing gear shimmy

Unlocking a nose landing gear in different flight conditions: folds, cusps and a swallowtail

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

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