Elasto/Visco-Plastic Dynamic Response of Axisymmetrical Shells by Overlay Model

1980 ◽  
Vol 102 (3) ◽  
pp. 257-263 ◽  
Author(s):  
S. Takezono ◽  
K. Tao ◽  
K. Kanezaki
Keyword(s):  
Dynamic Response ◽  
Bauschinger Effect ◽  
Shell Theory ◽  
Elastic Shell ◽  
Isotropic Hardening ◽  
Time Varying ◽  
Plastic Range ◽  
Rate Dependency ◽  
The Finite Difference Method ◽  
Overlay Model

The numerical analysis of the elasto/visco-plastic dynamic response of the axisymmetrical shells to the time-varying load is carried out by the use of the elasto/visco-plastic overlay model which is able to express the Bauschinger effect and the strain rate dependency. Namely Perzyna’s equation is used for the constitutive relation of each layer of the overlay model and as a whole, the Bauschinger effect and the influence of viscosity in plastic range of the materials are taken into account. The basic differential equations for the shells subjected to axisymmetrical loads are derived by extending Sanders’ elastic shell theory and the equations are numerically solved by the finite difference method. As a numerical example, the pressure vessel under semi-sinusoidal pressure load with respect to time is analyzed and the results are compared with ones in the case of isotropic hardening.

Analysis of Spectral Characteristics of Sound Waves Scattered from a Cracked Cylindrical Elastic Shell Filled with a Viscous Fluid

2013 ◽  
Vol 38 (3) ◽  
pp. 335-350 ◽  
Author(s):  
Olexa Piddubniak ◽  
Nadia Piddubniak
Keyword(s):  
Viscous Fluid ◽  
Shell Theory ◽  
Elastic Shell ◽  
Spectral Characteristics ◽  
Steel Shell ◽  
Sound Waves ◽  
Thin Cylindrical Shell ◽  
Shell Surface ◽  
Theory Approximation ◽  
Directivity Patterns

Abstract The scattering of plane steady-state sound waves from a viscous fluid-filled thin cylindrical shell weak- ened by a long linear slit and submerged in an ideal fluid is studied. For the description of vibrations of elastic objects the Kirchhoff-Love shell-theory approximation is used. An exact solution of this problem is obtained in the form of series with cylindrical harmonics. The numerical analysis is carried out for a steel shell filled with oil and immersed in seawater. The modules and phases of the scattering amplitudes versus the dimensionless wavenumber of the incident sound wave as well as directivity patterns of the scattered field are investigated taking into consideration the orientation of the slit on the elastic shell surface. The plots obtained show a considerable influence of the slit and viscous fluid filler on the diffraction process.

Local loads on a toroidal shell

1992 ◽  
Vol 27 (2) ◽  
pp. 59-66 ◽  
Author(s):  
D Redekop ◽  
F Zhang
Keyword(s):  
Cylindrical Shell ◽  
Shell Theory ◽  
Elastic Shell ◽  
Toroidal Shell ◽  
Pipe Bend ◽  
Local Loads ◽  
Simply Supported ◽  
Linear Elastic ◽  
Wide Range ◽  
Theory Solution

In this study the effect of local loads applied on a sectorial toroidal shell (pipe bend) is considered. A linear elastic shell theory solution for local loads is first outlined. The solution corresponds to the case of a shell simply supported at the two ends. Detailed displacement and stress results are then given for a specific shell with loadings centred at three positions; the crown circles, the extrados, and the intrados. These results are compared with results for a corresponding cylindrical shell. The paper concludes with a table summarizing results for characteristic displacements and stresses in a number of shells, covering a wide range of geometric parameters.

Vibration-based fault diagnosis of helical gear pair with tooth surface wear considering time-varying friction coefficient under mixed EHL condition

2021 ◽  
pp. 1-16
Author(s):  
Siyu Wang ◽  
Rupeng Zhu
Keyword(s):  
Dynamic Response ◽  
Hydrodynamic Lubrication ◽  
Helical Gear ◽  
Calculation Model ◽  
Tooth Surface ◽  
Time Varying ◽  
Gear Pair ◽  
Surface Wear ◽  
Mesh Stiffness ◽  
Helical Gear Pair

Abstract Based on “slice method”, the improved time-varying mesh stiffness (TVMS) calculation model of helical gear pair with tooth surface wear is proposed, in which the effect of friction force that obtained under mixed elasto-hydrodynamic lubrication (EHL) is considered in the model. Based on the improved TVMS calculation model, the dynamic model of helical gear system is established, then the influence of tooth wear parameters on the dynamic response is studied. The results illustrate that the varying reduction extents of mesh stiffness along tooth profile under tooth surface wear, in addition, the dynamic response in time-domain and frequency-domain present significant decline in amplitude under deteriorating wear condition.

Predictions of microtorsional experiments by micropolar plasticity

2005 ◽  
Vol 461 (2053) ◽  
pp. 189-205 ◽  
Author(s):  
Paschalis Grammenoudis ◽  
Charalampos Tsakmakis
Keyword(s):  
Size Effects ◽  
Bauschinger Effect ◽  
Kinematic Hardening ◽  
Circular Cylinders ◽  
Isotropic Hardening ◽  
Gradient Plasticity ◽  
Material Response ◽  
Micropolar Plasticity ◽  
Classical Plasticity ◽  
Hardening Rules

Kinematic hardening rules are employed in classical plasticity to capture the so–called Bauschinger effect. They are important when describing the material response during reloading. In the framework of thermodynamically consistent gradient plasticity theories, kinematic hardening effects were first incorporated into a micropolar plasticity model by Grammenoudis and Tsakmakis. The aim of the present paper is to investigate this model by predicting size effects in torsional loading of circular cylinders. It is shown that kinematic hardening rules compared with isotropic hardening rules, as adopted in the paper, provide more possibilities for modelling size effects in the material response, even if only monotonous loading conditions are considered.

Transient Small-Scale Yield Behavior of Textured Copper Tubing Under Biaxial Loading

1986 ◽  
Vol 108 (2) ◽  
pp. 127-134 ◽  
Author(s):  
Hamid Garmestani ◽  
Brent L. Adams
Keyword(s):  
Yield Surface ◽  
Bauschinger Effect ◽  
Biaxial Loading ◽  
Small Scale ◽  
Isotropic Hardening ◽  
Initial Surface ◽  
Transient Time ◽  
Dependent Behavior ◽  
Copper Tubing ◽  
Final Yield

Biaxial microplastic yielding (8 microstrain) of 101 copper tubing was studied at room temperature to assess the transient time-dependent behavior of subsequent yielding following small prestrains (2000 microstrain). The specimens investigated were thin-walled tubes loaded in variable combinations of uniaxial tension/compression and internal pressurization. Prestraining in three different directions introduced a Bauschinger effect as manifested by a translation of the yield surface in the direction of stressing. The yield surface also showed an expansion in size. Subsequent yield surfaces, measured at other time intervals, showed that the Bauschinger effect recovered up to 90 percent after 120 hours, and the final yield locus retained the same shape anisotropy as the initial surface. This implies a shift from kinematic to isotropic hardening. Hart’s phenomenological model was used to predict the experimental data. In this model, the Bauschinger effect and other shape changes of the yield surface are attributed to anelastic phenomena.

Tension—compression behaviour of annealed oxygen-free high-conductivity copper after strain cycling in the plastic range

1975 ◽  
Vol 10 (1) ◽  
pp. 10-18 ◽  
Author(s):  
P W J Oldroyd
Keyword(s):  
Bauschinger Effect ◽  
Strain Range ◽  
Compression Stress ◽  
Plastic Range ◽  
Stress Strain ◽  
Compression Properties ◽  
Compression Behaviour ◽  
Tension And Compression ◽  
Strain Cycling ◽  
Structural Strain

When copper is cycled between fixed limits of strain it ends towards a settled cyclic state. The two curves which form the tension-compression stress-strain loop will have the same shape but, no matter what point is chosen on the loop for the return to zero stress, the material will not be left with symmetrical tension-compression properties. This is because of the Bauschinger effect. It is demonstrated that the Bauschinger effect can be eliminated by cycling down to zero stress and zero strain using progressively decreasing strain amplitudes. Relatively few cycles suffice and, when the strain range is small, the structural strain-hardening effect is not noticeably reduced. Even with the largest range investigated (± 1 per cent plastic strain) the structural resoftening is slight. The significance of the subsequent tension and compression stress-strain curves is discussed.

Non-Linear Modal Interactions in a Suspension Rope System with Time-Varying Length

2006 ◽  
Vol 5-6 ◽  
pp. 217-224 ◽  
Author(s):  
Rodanthi Salamaliki-Simpson ◽  
Stefan Kaczmarczyk ◽  
Phil Picton ◽  
Scott Turner
Keyword(s):  
Dynamic Response ◽  
Equations Of Motion ◽  
Time Varying ◽  
Modal Interaction ◽  
Modal Interactions ◽  
Autoparametric Resonance ◽  
Non Linear ◽  
Varying Length ◽  
Host Structure ◽  
Rope System

This paper focuses on the investigation of the autoparametric coupling effects and modal interactions in a suspension rope system with a time varying length. Equations of motion of a multi-degree-of-freedom discrete, non-stationary and non-linear model are presented and are used to analyze the dynamic response of an elevator suspension rope system under resonance conditions. The equations of motion involve quadratic and cubic non-linear terms which are responsible for the modal interaction between the lateral and longitudinal oscillations of the rope and the car motions. The model takes into account the periodic excitations caused by motion of the host structure. The results confirm that adverse responses may arise and internal autoparametric resonance phenomena may occur.

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