scholarly journals Evaluation of Elastic-Plastic Surface Flaw Behavior and Related Parameters Using Surface Displacement Measurements

2009 ◽  
pp. 322-322-15 ◽  
Author(s):  
WR Lloyd ◽  
WG Reuter
Keyword(s):  
Surface Displacement ◽  
Surface Flaw ◽  
Elastic Plastic ◽  
Plastic Surface ◽  
Displacement Measurements

Microscopy and microindentation mechanics of single crystal Fe−3 wt. % Si: Part I. Atomic force microscopy of a small indentation

1993 ◽  
Vol 8 (6) ◽  
pp. 1291-1299 ◽  
Author(s):  
S. Harvey ◽  
H. Huang ◽  
S. Venkataraman ◽  
W.W. Gerberich
Keyword(s):  
Plastic Zone ◽  
Single Crystal ◽  
Surface Displacement ◽  
Plastic Zone Size ◽  
Force Microscopy ◽  
Elastic Plastic ◽  
Atomic Force ◽  
Plastic Indentation ◽  
Volume Estimates ◽  
Small Indentation

Atomic force microscope measurements of elastic-plastic indentation into an Fe−3 wt. % Si single crystal showed that the volume displaced to the surface is nearly equal to the volume of the cavity. The surface displacement profiles and plastic zone size caused by a 69 nm penetration of a Vickers diamond tip are reasonably represented by an elastic-plastic continuum model. Invoking conservation of volume, estimates of the number of dislocations emanating from the free surface are reasonably consistent with the number of dislocations that have formed in the plastic zone to represent an average calculated plastic strain of 0.044.

scholarly journals Time forecast of a break-off event from a hanging glacier

2016 ◽  
Vol 10 (3) ◽  
pp. 1191-1200 ◽  
Author(s):  
Jérome Faillettaz ◽  
Martin Funk ◽  
Marco Vagliasindi
Keyword(s):  
Real Time ◽  
Power Law ◽  
Surface Displacement ◽  
Early Warning Systems ◽  
Warning Systems ◽  
Safety Measures ◽  
Periodic Oscillations ◽  
Ice Volume ◽  
Surface Displacements ◽  
Displacement Measurements

Abstract. A cold hanging glacier located on the south face of the Grandes Jorasses (Mont Blanc, Italy) broke off on the 23 and 29 September 2014 with a total estimated ice volume of 105 000 m3. Thanks to accurate surface displacement measurements taken up to the final break-off, this event was successfully predicted 10 days in advance, enabling local authorities to take the necessary safety measures. The break-off event also confirmed that surface displacements experienced a power law acceleration along with superimposed log-periodic oscillations prior to the final rupture. This paper describes the methods used to achieve a satisfactory time forecast in real time and demonstrates, using a retrospective analysis, their potential for the development of early-warning systems in real time.

The surface velocity field in steep and breaking waves

1988 ◽  
Vol 189 ◽  
pp. 1-22 ◽  
Author(s):  
W. K. Melville ◽  
Ronald J. Rapp
Keyword(s):  
Water Waves ◽  
Surface Displacement ◽  
Breaking Waves ◽  
Surface Velocity ◽  
Breaking Wave ◽  
Laser Anemometry ◽  
Air Water Interface ◽  
Velocity Spectra ◽  
Displacement Measurements ◽  
Surface Drift

Coincident simultaneous measurements of the surface displacement and the horizontal velocity at the surface of steep and breaking waves are presented. The measurements involve a novel use of laser anemometry at the fluctuating air-water interface and clearly show the limitations of surface displacement measurements in characterizing steep and breaking wave fields. The measurements are used to examine the evolution of the surface drift velocity, spectra, wave envelopes, and forced long waves in unstable deep-water waves. Preliminary results of this work were reported by Melville & Rapp (1983).

Contact Analysis of Multilayered Elastic/Plastic Solids With Rough Surfaces for Decreasing Friction and Wear

2005 ◽  
Author(s):  
Shaobiao Cai ◽  
Bharat Bhushan
Keyword(s):  
Surface Roughness ◽  
Contact Area ◽  
Yield Criterion ◽  
Rough Surfaces ◽  
Three Dimensional ◽  
Surface Displacement ◽  
Maximum Displacement ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Von Mises

A numerical three-dimensional contact model is presented to investigate the contact behavior of multilayered elastic-perfectly plastic solids with rough surfaces. The surface displacement and contact pressure distributions are obtained based on the variational principle with fast Fourier transform (FFT)-based scheme. Von Mises yield criterion is used to determine the onset of yield. The effective hardness is modeled and plays role when the local displacement meet the maximum displacement criterion. Simulations are performed to obtain the contact pressures, fractional total contact area, fractional plastic contact area, and surface/subsurface stresses. These contact statistics are analyzed to study the effects of the layer-to-substrate ratios of stiffness and hardness, surface roughness, and layers thickness of rough, two-layered elastic/plastic solids. The results yield insight into the effects of stiffness and hardness of layers and substrates, surface roughness, and applied load on the contact performance. The layer parameters leading to low friction, stiction, and wear are investigated and identified.

Pavement displacement sensitivity to layer moduli

2002 ◽  
Vol 39 (6) ◽  
pp. 1395-1398
Author(s):  
Dieter Stolle
Keyword(s):  
Finite Element ◽  
Surface Displacement ◽  
Falling Weight Deflectometer ◽  
Contribution Ratio ◽  
Displacement Sensitivity ◽  
Stiffness Characteristics ◽  
Element Technique ◽  
Falling Weight ◽  
The Relationship ◽  
Displacement Measurements

The backcalculation of layer moduli using falling weight deflectometer data has proven to be challenging owing to the insensitivity of displacement measurements to the stiffness characteristics of some layers. This note describes a rigorous, yet simple, finite element technique for identifying the relationship between surface displacement and the elastic modulus of each layer. An example is given to demonstrate the application of the procedure.Key words: pavements, subgrade, backcalculation, contribution ratio.

Thermal-Elastic-Plastic Contact Analysis for Rough Bodies With a Semi-Analytical Method

2007 ◽  
Author(s):  
Vincent Boucly ◽  
Daniel Ne´lias ◽  
Michel Brunet
Keyword(s):  
Finite Elements ◽  
Static Loading ◽  
Frictional Heating ◽  
Sliding Contact ◽  
Transient Phenomena ◽  
Elastic Plastic ◽  
Plastic Surface ◽  
Engineering Problems ◽  
Interface Loading ◽  
Vertical Contact

Nowadays, Finite Elements softwares allow the user to model efficiently the contact between two solids. It is though necessary to make numerous assumptions in order to compute a contact in a reasonable time: generally surfaces are smooth and the mesh is too coarse to accurately study transient phenomena. Moreover, friction on the surface is rarely taken into account since models are usually axi-symmetric. This paper presents a semi-analytical formulation that allows computing the contact between two elastic-plastic solids with rough surfaces. The numerical methods used, i.e. the conjugate gradient and the fast Fourier transform allow to refine the mesh drastically. The main advantage of this formulation over Finite Elements method is the much shorter computation times. This model takes into consideration the hardening of material as well as friction and frictional heating at the interface. Loading can be vertical or rolling/sliding. This formulation allows realizing cyclic loadings in order to model numerous engineering problems as running-in, fretting, asperities tugging, as well as electro-mechanical micro-contacts. A comparison is made between the vertical contact (static loading) and the rolling/sliding contact (transient loading) in the case of an adiabatic elastic sphere rotating and pressed against a rough and stationary elastic-plastic surface. The influence of the friction coefficient is underlined.

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