A Note in Non-Intermittent Contact Problems of a Special Class of Ultrasonic Motors

1999 ◽  
Author(s):  
Thomas Sattel ◽  
Peter Hagedorn
Keyword(s):  
Numerical Simulations ◽  
Detailed Analysis ◽  
Special Class ◽  
Experimental Studies ◽  
Contact Problems ◽  
Dynamic Contact ◽  
Contact Model ◽  
Ultrasonic Motors ◽  
Intermittent Contact ◽  
Simple Contact

Abstract Contact problems play a key-role in ultrasonic motors. Our aim is the formulation of a contact model for stationary and non-stationary stator-rotor contact problems for a special class of non-intermittent ultrasonic motors. With the models proposed up to now, a detailed analysis of dynamic contact problems is only possible in a very limited manner. The simple contact model presented here can be used for numerical simulations and parameter studies and is verified by experimental studies carried out in our lab. First simulations show that, depending on the friction law, momentary perturbations can lead to self-excited vibrations in the rotor.

Vortex-Induced Vibrations of a Cylinder at Subcritical Reynolds Number

2011 ◽  
Author(s):  
Yoann Jus ◽  
Elisabeth Longatte ◽  
Jean-Camille Chassaing ◽  
Pierre Sagaut
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Cross Flow ◽  
Physical Analysis ◽  
Arbitrary Lagrangian Eulerian ◽  
Vortex Induced Vibrations ◽  
Low Mass

The present work focusses on the numerical study of Vortex-Induced Vibrations (VIV) of an elastically mounted cylinder in a cross flow at moderate Reynolds numbers. Low mass-damping experimental studies show that the dynamic behavior of the cylinder exhibits a three-branch response model, depending on the range of the reduced velocity. However, few numerical simulations deal with accurate computations of the VIV amplitudes at the lock-in upper branch of the bifurcation diagram. In this work, the dynamic response of the cylinder is investigated by means of three-dimensional Large Eddy Simulation (LES). An Arbitrary Lagrangian Eulerian framework is employed to account for fluid solid interface boundary motion and grid deformation. Numerous numerical simulations are performed at a Reynolds number of 3900 for both no damping and low-mass damping ratio and various reduced velocities. A detailed physical analysis is conducted to show how the present methodology is able to capture the different VIV responses.

Simulation of Dynamic Contact Problems in Parachute Systems

2004 ◽  
Vol 1 (7) ◽  
pp. 288-307 ◽  
Author(s):  
Zhenlong Xu ◽  
Michael Accorsi ◽  
John Leonard
Keyword(s):  
Contact Problems ◽  
Dynamic Contact

Crashworthiness Performance of Mass-Efficient Extruded Structures

2002 ◽  
Author(s):  
Robert R. Mayer ◽  
Weigang Chen ◽  
Anil Sachdev
Keyword(s):  
Numerical Simulations ◽  
Single Cell ◽  
Experimental Testing ◽  
Experimental Studies ◽  
Nonlinear Material ◽  
Dynamic Strain ◽  
Cell Design ◽  
Explicit Finite Element ◽  
The One ◽  
Crushing Behavior

Theoretical, numerical and experimental studies were conducted on the axial crushing behavior of traditional single-cell and innovative four-cell extrusions. Two commercial aluminum alloys, 6061 and 6063, both with two tempers (T4 and T6), were considered in the study. Testing coupons taken from the extrusions assessed the nonlinear material properties. A theoretical solution was available for the one-cell design, and was developed for the mean crushing force of the four-cell section. Numerical simulations were carried out using the explicit finite element code LS-DYNA. The aluminum alloy 6063T4 was found to absorb less energy than 6061T4, for both the one-cell and four-cell configurations. Both 6061 and 6063 in the T6 temper were found to have significant fracture in the experimental testing. Theoretical analysis and numerical simulations predicted a greater number of folds for the four-cell design, as compared to the one-cell design, and this was confirmed in the experiments. The theoretical improvement in energy absorption of 57% for the four-cell in comparison with the one-cell design was confirmed by experiment. The good agreement between the theoretical, numerical and experimental results allows confidence in the application of the theoretical and numerical tools for both single-cell and innovative four-cell extrusions. It was also demonstrated that these materials have very little dynamic strain rate effect.

Dynamic Contact Problems

2017 ◽  
pp. 267-292
Author(s):  
Mircea Sofonea ◽  
Stanisław Migórski
Keyword(s):  
Contact Problems ◽  
Dynamic Contact
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