Dynamic Stability of Unidirectional Fiber-Reinforced Viscoelastic Composite Plates

1989 ◽  
Vol 42 (11S) ◽  
pp. S39-S47 ◽  
Author(s):  
N. K. Chandiramani ◽  
L. Librescu
Keyword(s):  
Shear Deformation ◽  
Dynamic Stability ◽  
Stability Problem ◽  
Micromechanical Model ◽  
Shear Deformation Theory ◽  
Constitutive Law ◽  
Fiber Reinforced ◽  
Viscoelastic Composite ◽  
Unidirectional Fiber ◽  
The Stability

This paper deals with a dynamic stability analysis of unidirectional fiber-reinforced composite viscoelastic plates subjected to compressive edge loads. The integrodifferential equations governing the stability problem are obtained by using, in conjunction with a Boltzmann hereditary constitutive law for a 3-D viscoelastic medium, a higher-order shear deformation theory of orthotropic plates. Such a theory incorporates transverse shear deformation, transverse normal stress, and rotatory inertia effects. The solution of the stability problem as considered within this paper concerns the determination of the critical in-plane edge loads yielding the asymptotic instability. Numerical applications, based on material properties derived within the framework of Aboudi’s micromechanical model, are presented and pertinent conclusions concerning the nature of the loss of stability and the influence of various parameters are outlined.

Development of a Dynamic Stability Simulator for Articulated and Conventionaltractors Useful for Real-Time Safety Devices

2013 ◽  
Vol 394 ◽  
pp. 546-553 ◽  
Author(s):  
Fabrizio Mazzetto ◽  
Marco Bietresato ◽  
Renato Vidoni
Keyword(s):  
Real Time ◽  
Dynamic Stability ◽  
Stability Problem ◽  
Stability Index ◽  
Real Field ◽  
Circular Trajectory ◽  
Safety Devices ◽  
Test Platform ◽  
Agricultural Tractors ◽  
The Stability

The safety of agricultural tractors drivers is a very actual topic, especially when tractors operate on side slopes, such as in terraced vineyards. This work approaches the stability problem of articulated tractors by modelling, simulating and quantifying the safety of the driver with respect to both roll and pitch overturns. First of all, an articulated tractor has been modelled and simplified, after that a stability index has been defined and calculatedin several simulated slope conditions when the tractor travels along a circular trajectory; then, the obtained results have beencompared with respect to a conventional tractor. This work is a preliminary studyfor a tilting test platform for real vehicles, capable to reproduce real field conditions (slope, obstacles, roughness). Finally, some directives on how exploiting the obtained results for real-time safety devices have been formulated.

Dynamic Stability of Nonlinear Antisymmetrically-Laminated Cross-Ply Rectangular Plates

1989 ◽  
Vol 56 (2) ◽  
pp. 375-381 ◽  
Author(s):  
Andrzej Tylikowski
Keyword(s):  
Asymptotic Stability ◽  
Dynamic Stability ◽  
Material Properties ◽  
Stability Problem ◽  
Large Deflection ◽  
Direct Method ◽  
Rectangular Plates ◽  
Stability Criteria ◽  
The Stability ◽  
Liapunov's Direct Method

The dynamic stability problem is solved for rectangular plates that are laminated antisymmetrically about their middle plane and compressed by time-dependent deterministic or stochastic membrane forces. Moderately large deflection equations taking into account a coupling of in-plane and transverse motions are used. The asymptotic stability and almost-sure asymptotic stability criteria involving a damping coefficient and loading parameters are derived using Liapunov’s direct method. A relation between the stability of nonlinear equations and linearized ones is analyzed. An influence on the number of orthotropic layers, material properties for different classes of parametric excitation on stability domains is shown.

DYNAMIC STABILITY OF AN AXIALLY ACCELERATING VISCOELASTIC BEAM WITH TWO FIXED SUPPORTS

2006 ◽  
Vol 06 (01) ◽  
pp. 31-42 ◽  
Author(s):  
X.-D. YANG ◽  
L.-Q. CHEN
Keyword(s):  
Dynamic Stability ◽  
Viscosity Coefficient ◽  
Constitutive Law ◽  
Viscoelastic Beam ◽  
Kelvin Model ◽  
Averaged Equations ◽  
Beam Bending ◽  
The Mean ◽  
The Stability ◽  
The Galerkin Method

The dynamic stability of an axially accelerating viscoelastic beam with two fixed supports is investigated. The Kelvin model is used for the constitutive law of the beam. A small simple harmonic is allowed to fluctuate about the constant mean speed applied to the beam, and the governing equation is truncated using the Galerkin method based on the eigenfunctions of the stationary beam. The averaged equations are derived for the cases of subharmonic and combination resonance. Finally, numerical examples are presented to demonstrate the effects of the viscosity coefficient, the mean axial speed and the beam bending stiffness on the stability boundaries.

EFFECT OF TRANSVERSE NORMAL AND SHEAR DEFORMATION ON A FIBER-REINFORCED VISCOELASTIC BEAM RESTING ON TWO-PARAMETER ELASTIC FOUNDATIONS

2010 ◽  
Vol 02 (01) ◽  
pp. 87-115 ◽  
Author(s):  
A. M. ZENKOUR ◽  
M. N. M. ALLAM ◽  
MOHAMMED SOBHY
Keyword(s):  
Shear Deformation ◽  
Beam Theory ◽  
Effective Moduli ◽  
Fiber Reinforced ◽  
Governing Equations ◽  
Shear Deformations ◽  
Viscoelastic Composite ◽  
First Order ◽  
Elastic Foundations ◽  
Two Parameter

This article investigates the effect of transverse normal and shear deformations on a fiber-reinforced viscoelastic beams resting on two-parameter (Pasternak's) elastic foundations. The results are obtained by the refined sinusoidal shear deformation beam theory and compared with those obtained by the simple sinusoidal shear deformation beam theory, Timoshenko first-order shear deformation beam theory as well as Euler-Bernoulli classical beam theory. The effects of foundation stiffness on bending of viscoelastic composite beam are presented. The effective moduli methods are used to derive the governing equations of viscoelastic beams. The influences of several parameters, such as length-to-depth ratio, foundation stiffness, time parameter and other parameters on mechanical behavior of composite beams resting on Pasternak's foundations are investigated. Numerical results are presented and conclusions are formulated.

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