The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Tarun Kant - One of the best experts on this subject based on the ideXlab platform.
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Transient Dynamic Analysis of higher order sandwich and composite arches
Composite Structures, 2011Co-Authors: Sudhakar R. Marur, Tarun KantAbstract:A higher order refined model with isoparametric elements is proposed to study the Transient Dynamic response of laminated arches/curved beams. The strain field is modeled through cubic axial, cubic transverse shear and linear transverse normal strain components. As the cross-sectional warping is accurately modeled by this theory, the shear correction factor is rendered redundant. The stress–strain relationship is derived from an orthotropic lamina in a three-dimensional state of stress, so that angle-ply laminates can be studied through one-dimensional elements. Consistent mass matrix is constituted for the equation of motion, which is solved by Newmark integration scheme. The higher order formulation is validated with available results and subsequently applied to arches with various curvatures, aspect ratios, boundary conditions, loadings and lamination schemes to evaluate its Transient Dynamic performance and suitable conclusions are drawn.
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On the performance of higher order theories for Transient Dynamic Analysis of sandwich and composite beams
Computers & Structures, 1997Co-Authors: Sudhakar R. Marur, Tarun KantAbstract:Higher-order shear-deformable refined theories, based on isoparametric elements, are adopted for Transient Dynamic Analysis of symmetric and unsymmetric sandwich and composite beam constructions. These shear-correction coefficient free theories model cross sectional warping using nonlinear variation of inplane displacements across the depth. They also incorporate transverse shear stress in the formulation. A special lumping scheme is employed for the evaluation of diagonal mass matrix, and a central difference scheme is used for carrying out the integration of the equation of motion, to obtain the response history. Through numerical experiments, the efficacy of higher-order models in predicting displacements and stress, resultants over from the first-order theory, with respect to time, is clearly brought out in this paper.
Gang S. Chen - One of the best experts on this subject based on the ideXlab platform.
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Transient Dynamic Analysis of Vehicle Brake Creep Groan
Journal of Vibration Engineering & Technologies, 2019Co-Authors: Dejian Meng, Liangliang Shen, Lijun Zhang, Gang S. ChenAbstract:BackgroundBrake creep groan is getting more and more attention in vehicle brake design and development. However, many complex motions of brake creep groan have not been comprehensively, which are critical for the understanding and prevention of the problem.PurposeIn this paper, brake creep groan Dynamics are studied and analysed to research the mechanisms of creep groan.MethodVehicle road experiments on a slope road are performed to record creep groans using two tri-axial accelerometers, which are install at the caliper and suspension strut. History curves of oil pressure and caliper accelerations, time–frequency spectrogram of the vibrations, and largest Lyapunov exponent are calculated using Hilbert–Huang transform and empirical mode decomposition methods.Results and ConclusionThis study reveals that the sources of the brake creep groan include unstable sliding in addition to Transient and steady-state motions of stick–slip between disc and pad. It is found that one of the important sources of the creep groan is the unstable sliding, which has impulsive and discontinuous nature and has effects of hammering leading to strong excitation and wideband vibrations. It is also found that when creep groan occurs, multiple modes of the brake system and subsystems contribute to the complex vibrations. The existences and the properties of the stable, unstable, and chaotic vibrations associated with the creep groan are characterized, which depend on the system natures, excitations, and tribological conditions.
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Transient Dynamic Analysis of Vehicle Brake Creep Groan
Journal of Vibration Engineering & Technologies, 2019Co-Authors: Dejian Meng, Liangliang Shen, Lijun Zhang, Gang S. ChenAbstract:Brake creep groan is getting more and more attention in vehicle brake design and development. However, many complex motions of brake creep groan have not been comprehensively, which are critical for the understanding and prevention of the problem. In this paper, brake creep groan Dynamics are studied and analysed to research the mechanisms of creep groan. Vehicle road experiments on a slope road are performed to record creep groans using two tri-axial accelerometers, which are install at the caliper and suspension strut. History curves of oil pressure and caliper accelerations, time–frequency spectrogram of the vibrations, and largest Lyapunov exponent are calculated using Hilbert–Huang transform and empirical mode decomposition methods. This study reveals that the sources of the brake creep groan include unstable sliding in addition to Transient and steady-state motions of stick–slip between disc and pad. It is found that one of the important sources of the creep groan is the unstable sliding, which has impulsive and discontinuous nature and has effects of hammering leading to strong excitation and wideband vibrations. It is also found that when creep groan occurs, multiple modes of the brake system and subsystems contribute to the complex vibrations. The existences and the properties of the stable, unstable, and chaotic vibrations associated with the creep groan are characterized, which depend on the system natures, excitations, and tribological conditions.
María Jesús Elejabarrieta - One of the best experts on this subject based on the ideXlab platform.
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Homogenised finite element for Transient Dynamic Analysis of unconstrained layer damping beams involving fractional derivative models
Computational Mechanics, 2007Co-Authors: Fernando Cortés, María Jesús ElejabarrietaAbstract:This paper presents a homogenised finite element formulation for the Transient Dynamic Analysis of asymmetric and symmetric unconstrained layer damping beams in which the viscoelastic material is characterised by a five-parameter fractional derivative model. This formulation is based on the weighted residual method (Galerkin’s approach) providing a fractional matrix equation of motion. The application of Grünwald-Letnikov’s definition of the fractional derivatives allows to solve numerically the fractional equation by means of two different implicit formulations. Numerical examples for a cantilever beam with viscoelastic treatment are presented comparing the response provided by the proposed homogenised formulation with that of Padovan, based on the principle of virtual work. Different damping levels and load cases are analysed, as well as the influence of the truncation and time-step. From the numerical applications it can be concluded that the presented formulation allows to reduce significantly the degrees of freedom and consequently the computational time and storage needs for the Transient Dynamic Analysis of structural systems in which damping treatments have been applied by means of viscoelastic materials characterised by fractional derivative models.
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finite element formulations for Transient Dynamic Analysis in structural systems with viscoelastic treatments containing fractional derivative models
International Journal for Numerical Methods in Engineering, 2007Co-Authors: Fernando Cortés, María Jesús ElejabarrietaAbstract:This paper presents finite element formulations for Transient Dynamic Analysis in structural systems with damping treatments in which viscoelastic materials are characterized by means of fractional derivative models. In contrast to other formulations, such as that of Padovan employing the principle of virtual work, the proposed formulations begin from the local equation of linear momentum and make use of the weighted residual method, providing a matrix equation of motion involving fractional operators. The numerical approximations of these are developed through the Grunwald–Letnikov definition, which allows to formulate explicit and implicit numerical schemes. The principal advantage of the proposed formulations is that the history of the displacements and external forces must be stored, but not that of the stress, which reduces computational time and storage needs. Numerical applications are presented for a cantilever beam, where a viscoelastic treatment has been applied using damping material modelled by a five-parameter fractional derivative model. The results of the proposed formulation are compared among them and with those of Padovan for different damping values and for different load cases. The influence of the truncation of Grunwald coefficients and of the integration time-step is also investigated. Copyright © 2006 John Wiley & Sons, Ltd.
Sudhakar R. Marur - One of the best experts on this subject based on the ideXlab platform.
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Transient Dynamic Analysis of higher order sandwich and composite arches
Composite Structures, 2011Co-Authors: Sudhakar R. Marur, Tarun KantAbstract:A higher order refined model with isoparametric elements is proposed to study the Transient Dynamic response of laminated arches/curved beams. The strain field is modeled through cubic axial, cubic transverse shear and linear transverse normal strain components. As the cross-sectional warping is accurately modeled by this theory, the shear correction factor is rendered redundant. The stress–strain relationship is derived from an orthotropic lamina in a three-dimensional state of stress, so that angle-ply laminates can be studied through one-dimensional elements. Consistent mass matrix is constituted for the equation of motion, which is solved by Newmark integration scheme. The higher order formulation is validated with available results and subsequently applied to arches with various curvatures, aspect ratios, boundary conditions, loadings and lamination schemes to evaluate its Transient Dynamic performance and suitable conclusions are drawn.
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On the performance of higher order theories for Transient Dynamic Analysis of sandwich and composite beams
Computers & Structures, 1997Co-Authors: Sudhakar R. Marur, Tarun KantAbstract:Higher-order shear-deformable refined theories, based on isoparametric elements, are adopted for Transient Dynamic Analysis of symmetric and unsymmetric sandwich and composite beam constructions. These shear-correction coefficient free theories model cross sectional warping using nonlinear variation of inplane displacements across the depth. They also incorporate transverse shear stress in the formulation. A special lumping scheme is employed for the evaluation of diagonal mass matrix, and a central difference scheme is used for carrying out the integration of the equation of motion, to obtain the response history. Through numerical experiments, the efficacy of higher-order models in predicting displacements and stress, resultants over from the first-order theory, with respect to time, is clearly brought out in this paper.
Mohamed Torkhani - One of the best experts on this subject based on the ideXlab platform.
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A beam to 3D model switch in Transient Dynamic Analysis
Finite Elements in Analysis and Design, 2014Co-Authors: Mikhael Tannous, Patrice Cartraud, David Dureisseix, Mohamed TorkhaniAbstract:Transient structural Dynamic analyses often exhibit different phases, which enable one to use an adaptive modeling. Thus, a 3D model is required for a better understanding of local or non-linear effects, whereas a simplified beam model is sufficient for simulating the linear phenomena occurring for a long period of time. This paper proposes a method which enables one to switch from a beam to a 3D model during a Transient Dynamic Analysis, and thus, allows one to reduce the computational cost while preserving a good accuracy. The method is validated through comparisons with a 3D reference solutioncomputed during all the simulation.
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A beam to 3D model switch in Transient Dynamic Analysis
2012Co-Authors: Mikhael Tannous, Patrice Cartraud, David Dureisseix, Mohamed TorkhaniAbstract:Many industrial problems involving slender structures in Transient Dynamics require a 3D model for a better understanding of local or non linear effects that occur along a small period of time, whereas a simplified beam model can be sufficient for simulating the linear phenomena occurring for a long period of time. This paper proposes a method which enables to switch from a beam to a 3D model during a Transient Dynamic Analysis solved with a time integration technique. Thus, this method allows to reduce the computational cost while preserving a good accuracy. Starting with the beam model, at switch moment ts, a 3D solution is constructed as the sum of a cross-section rigid body displacement corresponding to the classical Timoshenko kinematical assumption and a 3D correction which accounts for cross-section deformation. This correction is obtained from the solution of a static problem and may be computed on three consecutive time steps (the switch instant, the previous and the following steps) thus allowing to make a velocity and acceleration corrections based on the three static computations. The Dynamic simulation is initialized at ts by the displacements, velocities and accelerations being computed. The method is validated through comparisons with a reference solution corresponding to the 3D model solution used during all the simulation.
