Analysis and design of a nonlinear stiffness and damping system with a scissor-like structure

2019 ◽

Vol 233 (15) ◽

pp. 5674-5688

Author(s):

PS Suresh ◽

Niranjan K Sura ◽

K Shankar

Keyword(s):

Dynamic Response ◽

Nonlinear Dynamic ◽

Landing Gear ◽

Flight Mechanics ◽

Dynamic Responses ◽

Nonlinear Stiffness ◽

Response Model ◽

Nonlinear Dynamic Response ◽

Vertical Descent ◽

Stiffness And Damping

The dynamic responses simulation of aircraft as rigid body considering heave, pitch, and roll motions, coupled onto a tricycle landing gear arrangement is presented. Equation of motion for each landing gear consists of un-sprung mass vertical and longitudinal motions considering strut nonlinear stiffness and damping combined with strut bending flexibility. Initially, the nonlinear dynamic response model is subjected to an input of riding over staggered bump and the responses are compared with linear landing gear model. It is observed that aircraft dynamics and important landing gear events such as vertical, spin-up and spring-back are truly represented with nonlinear stiffness and damping model considering strut bending flexibility. Later, landing response analysis is performed, with the input from nonlinear flight mechanics model for several vertical descent rate cases. The aircraft and landing gear dynamic responses such as displacement, velocity, acceleration, and reaction forces are obtained. The vertical and longitudinal drag forces from the nonlinear dynamic response model is compared with “Book-case method” outlined in landing gear design technical specifications. From the reaction force ratio calculation, it is shown that for lower vertical descent rate case the predicted loads are lesser using nonlinear dynamic response model. The same model for higher vertical descent rate cases predicts higher ratios on vertical reaction for main landing gear and longitudinal reaction for nose landing gear, respectively. The scope for increase in fatigue life for low vertical descent rate landing covering major design spectrum and the concern for static strength and structural integrity consideration for higher vertical descent rate cases are discussed in the context of event monitoring on aircraft in services.

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Numerical Modeling and Analysis of Nonlinear Dynamic Response for a Bolted Joint Beam Considering Interface Frictional Contact

Volume 4A: Dynamics, Vibration, and Control ◽

10.1115/imece2018-86743 ◽

2018 ◽

Author(s):

Dongwu Li ◽

Chao Xu ◽

Dong Wang ◽

Lihua Wen

Keyword(s):

Constitutive Model ◽

Dynamic Response ◽

Numerical Results ◽

Experimental Results ◽

Bolted Joints ◽

Interface Element ◽

Nonlinear Stiffness ◽

Friction Contact ◽

Structural Dynamic ◽

Stiffness And Damping

For an assembled structure with many bolted joints, predicting its dynamic response with high fidelity is always a difficult problem, because of the nonlinearity introduced by friction contact between jointed interfaces. The friction contact results in nonlinear stiffness and damping to a structure. To realize predictive simulation in structural dynamic design, these nonlinear behaviors must be carefully considered. In this paper, the dynamics of a multi-bolt jointed beam is calculated. A modified IWAN constitutive model, which can consider both tangential micro/macro slip and nonzero residual stiffness at macroslip phase, is developed to model nonlinear contact behaviors due to joint interfaces. A whole interface element integrating the proposed constitutive model is developed. The element is used to model the nonlinear stiffness and damping caused by bolted joints. The interface element is placed between the two contact interfaces. The other part of the beam is modeled by linear beam elements. A Matlab code is developed to realize the proposed nonlinear finite element dynamic analysis method. A hammer impact experiment for the bolt-jointed beam is conducted under different excitation force levels. The calculated nonlinear numerical results are compared with experimental results. It is shown that the effect of joint nonlinearity on structural dynamics can be observed from the response predicted by the proposed method. The numerical results agree well with the experimental results. This work validates the necessary of using nonlinear joint model for dynamic simulation of jointed structures.

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Study on Nonlinear Damping Properties of Hydro-Pneumatic Suspension System for XP302-Pneumatic Tyred Roller

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.945-949.987 ◽

2014 ◽

Vol 945-949 ◽

pp. 987-991

Author(s):

Bang Sheng Xing ◽

Ning Ning Wang ◽

Le Xu

Keyword(s):

Dynamic Performance ◽

Nonlinear Damping ◽

Suspension System ◽

Nonlinear Stiffness ◽

Damping Properties ◽

Vehicle Dynamic ◽

Nonlinear Mathematical Model ◽

Computer Simulation Program ◽

Pneumatic Suspension ◽

Stiffness And Damping

The nonlinear stiffness and damping properties of the hydro-pneumatic suspension system are introduced, and the nonlinear mathematical model of it is established. Using MATLAB 2009b to establish the computer simulation program and draw out the nonlinear stiffness curve and damping properties curve of the hydro-pneumatic suspension system. Then, researching the influences of related parameters' changes on the nonlinear stiffness and damping properties of the hydro-pneumatic suspension system. The simulation of vehicle dynamic performance research's foundation is provided.

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The Analysis and Design Study of High Speed Robotic Devices

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.282.18 ◽

2013 ◽

Vol 282 ◽

pp. 18-26 ◽

Cited By ~ 4

Author(s):

Štefan Havlík ◽

Jaroslav Hricko

Keyword(s):

High Speed ◽

Positional Accuracy ◽

Analysis And Design ◽

Positioning Devices ◽

Robotic Devices ◽

And Performance ◽

Improving Accuracy ◽

Kinematic Mechanisms ◽

Stiffness And Damping ◽

Made In

The problem of multi d.o.f. positioning devices based on compact compliant kinematic mechanisms is to guarantee the desired positional accuracy in static and especially in dynamic modes of operation. The study of accuracy and performance analysis of high speed devices is made in this paper. The influence of differences between stiffness and damping coefficients in actuated directions as well as mutual cross couplings between them are discussed in details and performance characteristics of such complex systems are simulated. As proposed the problem of improving accuracy can be solved by insertion of the compensation member into control system that could be integrated in parallel or serial way. The presented approach enables to verify the dynamical range of operation for small / micro positioning devices performing precise trajectory following tasks.

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Influence of the "Ghost Reed" Simplification on the Bifurcation Diagram of a Saxophone Model

Acta Acustica united with Acustica ◽

10.3813/aaa.919409 ◽

2019 ◽

Vol 105 (6) ◽

pp. 1291-1294 ◽

Cited By ~ 1

Author(s):

Tom Colinot ◽

Louis Guillot ◽

Christophe Vergez ◽

Philippe Guillemain ◽

Jean-Baptiste Doc ◽

...

Keyword(s):

Bifurcation Diagram ◽

Contact Force ◽

Nonlinear Stiffness ◽

Impact Model ◽

Bifurcation Diagrams ◽

Pressure Parameter ◽

Stiffness And Damping ◽

The Impact

This paper presents how the bifurcation diagram of a saxophone model is affected by the contact force limiting the displacement of the reed when it strikes the mouthpiece lay. The reed impact is modeled by a nonlinear stiffness and damping activated by contact with the lay. The impact model is compared with the "ghost reed" simplification, where the reed moves through the lay unimpeded. Bifurcation diagrams in both cases are compared, in terms of amplitude of the oscillations and location of the bifurcations, on the solution branches corresponding to the first and second register. The ghost reed simplification has limited influence at low values of the blowing pressure parameter: the diagrams are similar. This is true even for "beating reed" regimes, in which the reed coincides with the lay. The most noticeable discrepancies occur near the extinction of the oscillations, at high blowing pressure.

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Identification of Nonlinear Stiffness and Damping Parameters Using a Hybrid Approach

AIAA Journal ◽

10.2514/1.j060461 ◽

2021 ◽

pp. 1-10

Author(s):

Rui Zhu ◽

Qingguo Fei ◽

Dong Jiang ◽

Stefano Marchesiello ◽

Dario Anastasio

Keyword(s):

Hybrid Approach ◽

Nonlinear Stiffness ◽

Stiffness And Damping

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Jump-based estimation for nonlinear stiffness and damping parameters

Journal of Vibration and Control ◽

10.1177/1077546318777414 ◽

2018 ◽

Vol 25 (2) ◽

pp. 325-335 ◽

Cited By ~ 6

Author(s):

Ze-Qi Lu ◽

Guang-Shen Hu ◽

Hu Ding ◽

Li-Qun Chen

Keyword(s):

Estimation Method ◽

Excitation Amplitude ◽

Nonlinear Stiffness ◽

Response Curves ◽

Strongly Nonlinear ◽

Parameter Estimations ◽

Data Yield ◽

Stiffness And Damping ◽

Jump Frequencies ◽

Analytical Expressions

To overcome the limitation that only stiffness nonlinearity can be estimated via jump frequencies, this work introduces jump amplitudes as a supplement condition in the estimation of both stiffness and damping nonlinearities. An estimation method is proposed for a single-degree-of-freedom system containing both stiffness and damping nonlinearities. The idea may be applied to other nonlinear systems. The method is based on the measurements of both jump frequencies and jump amplitudes of the system subject to swept-sine excitations respectively in frequency and in amplitude. The experimental data yield frequency response curves at a fixed excitation amplitude and amplitude response curves at a fixed frequency. Based on the measured jump frequencies and jump amplitudes of the displacements, the system parameters can be determined by the method of harmonic balance. A numerical example is presented to demonstrate the application of the proposed approach and to check approximate explicit analytical expressions of the parameter estimation. To validate the effectiveness of the proposed approach, an experiment is performed on a vibration isolator with strongly nonlinear stiffness and damping. The estimation results show that the proposed method can estimate the stiffness and the damping parameters of the system with strong nonlinearities. Hence exploiting the knowledge about nonlinear jump phenomena is a promising approach to parameter estimations.

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