A Comparison of Transient and Steady State Finite Element Analyses of the Forced Response of a Frictionally Damped Beam

1985 ◽  
Vol 107 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Chia-Hsiang Menq ◽  
J. H. Griffin
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Forced Response ◽  
Finite Element Analyses ◽  
Transient And Steady State

New Mixed Finite Element Formulations for Transient and Steady State Creep Problems

1989 ◽  
Vol 42 (11S) ◽  
pp. S150-S156
Author(s):  
Abimael F. D. Loula ◽  
Joa˜o Nisan C. Guerreiro
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Mixed Finite Element ◽  
Finite Element Approximation ◽  
Steady State Creep ◽  
Element Approximation ◽  
New Approach ◽  
Finite Element Approximations ◽  
Transient Problems ◽  
Transient And Steady State

We apply the mixed Petrov–Galerkin formulation to construct finite element approximations for transient and steady-state creep problems. With the new approach we recover stability, convergence, and accuracy of some Galerkin unstable approximations. We also present the main results on the numerical analysis and error estimates of the proposed finite element approximation for the steady problem, and discuss the asymptotic behavior of the continuum and discrete transient problems.

Transient and steady state behaviour of elasto–aerodynamic air foil bearings, considering bump foil compliance and top foil inertia and flexibility: A numerical investigation

2017 ◽  
Vol 231 (10) ◽  
pp. 1235-1253 ◽  
Author(s):  
Bo B. Nielsen ◽  
Ilmar F. Santos
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Elastic Foundation ◽  
Parameter Study ◽  
Finite Element Models ◽  
Foil Bearings ◽  
Aerodynamic Pressure ◽  
Foil Bearing ◽  
Foundation Model ◽  
Transient And Steady State

This work gives a theoretical contribution to the problem of modelling air foil bearings considering large sagging effects in the calculation of the non-linear transient and steady state response of a rigid rotor. This paper consists of two parts: the development of a miltiphysics model of the air foil bearing, and a numerical parameter study of a rigid journal supported in an air foil bearing with a partially supported top foil. The mathematical model of the air foil bearing is centred around the finite element models of both the air film and the top foil structure. These finite element models utilise two types of eight-node isoparametric elements. The rotor is modelled as a rigid body without rotational inertia, i.e. as a journal. The bump foil is included via a bilinear version of the simple elastic foundation model. This paper introduces the bilinear simple elastic foundation model, which combined with the top foil structure model, enables a separation of the top foil and the bump foil. A phenomenon associated within areas of the top foil is where the aerodynamic pressure is sub-ambient. The parameter study investigates the performance of three air foil bearings with partially supported top foils and one air foil bearing with a fully supported top foil. The steady state responses of a journal supported by these air foil bearings are investigated for varied rotational speeds and journal unbalances as well as the top foil sagging in the unsupported area. The study reveals that sub-harmonic vibrations associated with a large journal unbalance can be eliminated by a proper design layout of the bump foil, i.e. placement of the unsupported area. The positive effect is attributed to ‘equivalent shallow pockets’ formed by the sagging top foil.

Transient and Steady-State Dynamic Finite Element Modeling of Belt-Drives

2002 ◽  
Vol 124 (4) ◽  
pp. 575-581 ◽  
Author(s):  
Michael J. Leamy ◽  
Tamer M. Wasfy
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Angular Velocity ◽  
Frictional Contact ◽  
Finite Element Solution ◽  
Belt Drive ◽  
Element Solution ◽  
Dynamic Finite Element ◽  
Time Accuracy ◽  
Transient And Steady State

In this study, a dynamic finite element model is developed for pulley belt-drive systems and is employed to determine the transient and steady-state response of a prototypical belt-drive. The belt is modeled using standard truss elements, while the pulleys are modeled using rotating circular constraints, for which the driver pulley’s angular velocity is prescribed. Frictional contact between the pulleys and the belt is modeled using a penalty formulation with frictional contact governed by a Coulomb-like tri-linear friction law. One-way clutch elements are modeled using a proportional torque law supporting torque transmission in a single direction. The dynamic response of the drive is then studied by incorporating the model into an explicit finite element code, which can maintain time-accuracy for large rotations and for long simulation times. The finite element solution is validated through comparison to an exact analytical solution of a steadily-rotating, two-pulley drive. Several response quantities are compared, including the normal and tangential (friction) force distributions between the pulleys and the belt, the driven pulley angular velocity, and the belt span tensions. Excellent agreement is found. Transient response results for a second belt-drive example involving a one-way clutch are used to demonstrate the utility and flexibility of the finite element solution approach.

Numerical Simulation of Polymeric Gels

2015 ◽  
Author(s):  
Shawn A. Chester
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Steady State ◽  
Large Deformation ◽  
Governing Equations ◽  
Numerical Examples ◽  
Polymeric Gels ◽  
Finite Element Package ◽  
Fluid Diffusion ◽  
Transient And Steady State

Following [1], a theory for coupled fluid diffusion and large deformation is implemented as a user-element subroutine in the commercial finite element package ABAQUS. The governing equations are summarized along with details of the constitutive theory. A few numerical examples are provided to show the robustness of this methodology in both transient and steady state conditions.

Forced Response of PZT Glide Heads1

2000 ◽  
Vol 122 (4) ◽  
pp. 780-786 ◽  
Author(s):  
Jin-Hui Ou-Yang ◽  
Alex Y. Tsay ◽  
I. Y. Shen ◽  
C.-P. Roger Ku ◽  
David Kuo
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Laser Doppler Vibrometer ◽  
Forced Response ◽  
Finite Element Analyses ◽  
Pass Filter ◽  
Electric Circuits ◽  
Resonance Frequencies ◽  
Before And After ◽  
The Impact

This paper studies forced response of PZT glide heads through calibrated experiments and finite element analyses. The PZT glide heads consist of an Al2O3TiC slider and a PZT transducer. In the first part of the research, the PZT transducer serves as an actuator exciting the glide heads from 100 kHz to 1.3 MHz. A laser Doppler vibrometer (LDV) and an impedance analyzer are used to measure frequency response functions (FRF) and PZT impedance. In addition, the response of the PZT glide heads is simulated through finite element analyses (FEA). The FEA predict the resonance frequencies with less than 5 percent difference. For the first two slider modes, the FEA also predict resonance amplitudes with good accuracy. In the second part of the research, the PZT transducer serves as a sensor, and the glide head is subjected to an impact force. To produce short impacts experimentally, miniature balls are dropped to the glide heads. The impact force is estimated through the impact duration and the momentum change before and after the impact. Then the impact force and the PZT output voltage are processed to produce FRF. Since the PZT sensor and its circuit form a high-pass filter, the FEA need to consider the slider, the PZT transducer, and the electric circuits simultaneously to produce meaningful results. The FEA predictions agree with the experimental measurements for the first two slider modes as well. [S0742-4787(00)01004-3]

Elasto-Plastic and Creep Analysis of a First Stage Blade in a Land Based Gas Turbine Under Steady State Operating Conditions

2000 ◽  
Author(s):  
Takayuki Sakai ◽  
Takashi Ogata ◽  
Akiyoshi Nomoto ◽  
Kazunori Watanabe
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbine ◽  
Creep Strain ◽  
Strain Distribution ◽  
Creep Damage ◽  
Finite Element Analyses ◽  
Combustion Gas ◽  
Cooling Air ◽  
Critical Portion

Because first stage rotor blades are used under severe temperature and stress conditions, damage evaluation procedure for the blades is one of key technology to reduce maintenance costs for land based gas turbine. To calculate damage of the blade, stress/strain distribution should be predicted based on temperature distribution. In this study, first stage blades were analyzed by a finite element method to discuss damage profile within the blade under steady state operating condition. At first, 2-D finite element analyses were carried out to study effect of variation of combustion gas and cooling air conditions on the stress/strain distribution of the blade mid height. As a result, change on cooling air condition did not show significant effect on creep strain distribution within the blade section, whereas increase of inlet temperature of combustion gas caused increase of thermal stress and creep strain. Then, 3-D finite element analyses were carried out to identify critical portion of the whole blade in terms of fatigue and creep damage. Consequently, it was found that the leading edge of the blade would be subjected to larger plastic strain that cause fatigue damage. On the other hand, it was suggested that one-third height of the blade at pressure side surface would be the critical portion in terms of creep damage.

Lateral Stiffness and Dynamic Properties of Separable Polyurethane Tires for a Folding Bike

2012 ◽  
Author(s):  
Sarom Ryu ◽  
Jaehyung Ju ◽  
Doo-Man Kim ◽  
Jin-Kyu Kim
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Dynamic Properties ◽  
Lateral Force ◽  
Sustainable Transportation ◽  
Lateral Stiffness ◽  
Finite Element Code ◽  
Material Models ◽  
Increasing Demand ◽  
Transient And Steady State

With an increasing demand to reduce CO2 emissions, sustainable transportation tools are drawing attention. After having reported on our initial design of a folding bike as an easy-to-carry sustainable transportation tool, we now explore lateral stiffness as well as other dynamic properties, including modal behaviors and steady state vibration characteristics. In this study, we investigate the lateral force of a separable polyurethane solid tire with varying slip and camber angles. Nonlinear hyperelastic material models are used with a commercial finite element code, ABAQUS/Standard. Transient and steady state dynamic properties of the separable bike wheel and tire are also investigated with the ABAQUS/Explicit code, and the results are compared with those of the pneumatic counterpart.

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