Development and Validation of Non-linear Suspension System

Automotive dampers are an important element of a vehicle's suspension system for controlling road handling and passenger ride comfort. Many automotive dampers have non-linear asymmetric characteristics to accommodate the incompatible requirements between ride comfort and road handling, thus the ride comfort engineer requires techniques that can characterize this non-linear behaviour and provide models of the dampers for use in ride performance simulations of the full suspension system. The work presented in this paper is concerned with developing a frequency domain technique using higher order frequency response functions (HFRFs) to characterize a Monroe automotive damper. The principal diagonals and multidimensional surfaces of the HFRFs up to third order are obtained. Non-linear damping coefficients for the damper are derived from the HFRFs and the energy transfer properties are investigated. The results show that the majority of the HFRFs contain no peaks or resonances, indicating that the damper has no preferred frequencies for energy transfer. The accuracy of the damping coefficients determined from the HFRFs is poor. This is due to the inability of the technique to measure the pure HFRFs and separate the effects of non-linearities in the input actuator from those in the damper. It is concluded that these constraints currently impose some limit on the use of the methodology.

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Investigation on chaotic motion in hysteretic non-linear suspension system with multi-frequency excitations

Mechanics Research Communications ◽

10.1016/j.mechrescom.2003.10.002 ◽

2004 ◽

Vol 31 (2) ◽

pp. 229-236 ◽

Cited By ~ 54

Author(s):

Shaohua Li ◽

Shaopu Yang ◽

Wenwu Guo

Keyword(s):

Chaotic Motion ◽

Suspension System ◽

Non Linear

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Non-linear optimal control of a semi-active vehicle suspension system

Chaos Solitons & Fractals ◽

10.1016/0960-0779(94)00166-n ◽

1995 ◽

Vol 5 (9) ◽

pp. 1603-1617 ◽

Cited By ~ 16

Author(s):

T.J. Gordon

Keyword(s):

Optimal Control ◽

Suspension System ◽

Vehicle Suspension ◽

Linear Optimal Control ◽

Non Linear ◽

Vehicle Suspension System ◽

Active Vehicle Suspension System

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Development and validation of a non-linear spectral model for water waves over variable depth

European Journal of Mechanics - B/Fluids ◽

10.1016/j.euromechflu.2015.12.004 ◽

2016 ◽

Vol 57 ◽

pp. 115-128 ◽

Cited By ~ 18

Author(s):

M. Gouin ◽

G. Ducrozet ◽

P. Ferrant

Keyword(s):

Water Waves ◽

Spectral Model ◽

Variable Depth ◽

Non Linear ◽

Development And Validation

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Viscoelastic Behavior of Carbon Nanotube Yarns and Twisted Coils

Volume 12: Materials: Genetics to Structures ◽

10.1115/imece2018-88095 ◽

2018 ◽

Author(s):

Pouria Khanbolouki ◽

Mehran Tehrani

Keyword(s):

Carbon Nanotube ◽

Viscoelastic Model ◽

Viscoelastic Behavior ◽

Energy Harvesters ◽

Linear Behavior ◽

Non Linear ◽

Stretchable Conductors ◽

Linear Viscoelastic Behavior ◽

Linear Viscoelastic ◽

Development And Validation

Coiled structures made from polymer and Carbon Nanotube (CNT) yarns are used as artificial muscles, stretchable conductors, and energy harvesters. The purpose of this work is to present our latest understanding of the mechanical behavior of these CNT-based structures. CNT yarns are fabricated by inserting twists in sheets spun from CNT forests. Over twisting the CNT yarns results in coiled CNT yarns, similar to a spring where the spring radius is comparable to the diameter of the CNT yarn. In this study, we explain the development and validation of a viscoelastic model, to capture damping and hysteresis in CNT yarns under quasi-static and dynamic loads. Confirmation of linear viscoelastic behavior of CNT yarns can lead us to the development of a model for coiled CNT yarns. Coiled CNT yarns, on the other hand, show a complex non-linear viscoelastic behavior. Possible mechanisms responsible for this non-linear behavior are discussed.

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Development and Validation of a Non-Linear Viscoelastic Viscoplastic Stress Model for a PFCB/PVDF Fuel Cell Membrane

Volume 8: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2012-85427 ◽

2012 ◽

Cited By ~ 1

Author(s):

Jessica A. Wright ◽

Michael W. Ellis ◽

David A. Dillard ◽

Scott W. Case ◽

Robert B. Moore ◽

...

Keyword(s):

Polyvinylidene Fluoride ◽

Numerical Models ◽

Proton Exchange ◽

Mechanical Degradation ◽

Stress Model ◽

Uniaxial Creep ◽

Non Linear ◽

Viscoelastic Modulus ◽

Linear Viscoelastic ◽

Development And Validation

Proton exchange membranes (PEMs) in operating fuel cells are subjected to varying thermal and hygral loads while under mechanical constraint imposed within the compressed stack. Swelling during hygrothermal cycles can result in residual in-plane tensile stresses in the membrane and lead to mechanical degradation or failure through thinning or pinhole development. Numerical models can predict the stresses resulting from applied loads based on material characteristics, thus helping to guide the development of more durable membrane materials. In this work, a non-linear viscoelastic stress model based on the Schapery constitutive formulation is used with a Zapas-Crissman viscoplastic term to describe the response of a novel membrane material comprised of a blend of perfluorocyclobutane (PFCB) ionomer and polyvinylidene fluoride (PVDF). Uniaxial creep and recovery tests are used to establish the time dependent linear viscoelastic modulus as well as the fitting parameters for the non-linear viscoelastic viscoplastic model. The stress model is implemented in a commercial finite element code, Abaqus®, to predict the response of a membrane subjected to mechanical loads. The stress model is validated by comparing predicted and experimental responses for membranes subjected to stress relaxation and multiple step creep loads in uniaxial tension.

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Improved optimal sliding mode control for a non-linear vehicle active suspension system

Journal of Sound and Vibration ◽

10.1016/j.jsv.2017.02.017 ◽

2017 ◽

Vol 395 ◽

pp. 1-25 ◽

Cited By ~ 45

Author(s):

Shi-An Chen ◽

Jun-Cheng Wang ◽

Ming Yao ◽

Young-Bae Kim

Keyword(s):

Sliding Mode Control ◽

Sliding Mode ◽

Active Suspension ◽

Suspension System ◽

Mode Control ◽

Non Linear

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Electrostatic Suspension System for Gyroscopes with Minimum Electrical Disturbing Torque via Non-Linear Pre-Compensation

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1243/pime_proc_1996_210_353_02 ◽

1996 ◽

Vol 210 (2) ◽

pp. 123-127 ◽

Cited By ~ 1

Author(s):

W Q Yang

Keyword(s):

Control System ◽

Steady State ◽

Position Control ◽

Complete System ◽

Suspension System ◽

System Operation ◽

Non Linear ◽

Position Control System ◽

Transient And Steady State ◽

Steady State Performance

The new electrostatic suspension system (ESS) presented here is applicable to electrostatically suspended gyroscopes (ESG). The electrical disturbing torque (EDT) acting on the gyro rotor is reduced to much lower levels than possible with the conventional methods, thereby increasing the attainable accuracy of the instrument. This is achieved by eliminating the conventional pre-load voltage and instead applying only control voltages via an analogue non-linear pre-compensator to achieve linear position control system operation despite the square law relating the suspension force to the applied voltage. The transient and steady state performance of the complete system, with changes in position reference and external disturbing forces, are examined with the aid of computer simulations.

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