scholarly journals Stick-slip analysis of a circular point contact between a rigid sphere and a flat unidirectional composite with cylindrical fibers

2011 ◽  
Vol 48 (25-26) ◽  
pp. 3510-3520 ◽  
Author(s):  
Julien Leroux ◽  
Daniel Nélias
Keyword(s):  
Point Contact ◽  
Unidirectional Composite ◽  
Rigid Sphere ◽  
Stick Slip ◽  
Circular Point

STUDYING THE CONTACT POINT AND INTERFACE MOVING IN A SINUSOIDAL TUBE WITH LATTICE BOLTZMANN METHOD

2001 ◽  
Vol 15 (09) ◽  
pp. 1287-1303 ◽  
Author(s):  
HAI-PING FANG ◽  
LE-WEN FAN ◽  
ZUO-WEI WANG ◽  
ZHI-FANG LIN ◽  
YUE-HONG QIAN
Keyword(s):  
Boundary Conditions ◽  
Contact Line ◽  
Lattice Boltzmann ◽  
Complex Geometry ◽  
Contact Point ◽  
Point Contact ◽  
Immiscible Fluids ◽  
Lattice Boltzmann Model ◽  
Stick Slip ◽  
Bounce Back

The multicomponent nonideal gas lattice Boltzmann model by Shan and Chen (S-C) is used to study the immiscible displacement in a sinusoidal tube. The movement of interface and the contact point (contact line in three-dimension) is studied. Due to the roughness of the boundary, the contact point shows "stick-slip" mechanics. The "stick-slip" effect decreases as the speed of the interface increases. For fluids that are non-wetting, the interface is almost perpendicular to the boundaries at most time, although its shapes at different position of the tube are rather different. When the tube becomes narrow, the interface turns a complex curves rather than remains simple menisci. The velocity is found to vary considerably between the neighbor nodes close to the contact point, consistent with the experimental observation that the velocity is multi-values on the contact line. Finally, the effect of three boundary conditions is discussed. The average speed is found different for different boundary conditions. The simple bounce-back rule makes the contact point move fastest. Both the simple bounce-back and the no-slip bounce-back rules are more sensitive to the roughness of the boundary in comparison with the half-way bounce-back rule. The simulation results suggest that the S-C model may be a promising tool in simulating the displacement behaviour of two immiscible fluids in complex geometry.

A Novel Three-Dimensional Finite Element Model to Simulate Third Body Effects on Fretting Wear of Hertzian Point Contact in Partial Slip

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Arman Ahmadi ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Three Dimensional ◽  
Point Contact ◽  
Fretting Wear ◽  
Partial Slip ◽  
Wear Particles ◽  
Third Body ◽  
Stick Slip ◽  
The Third

Abstract In this investigation, a finite element (FE) model was developed to study the third body effects on the fretting wear of Hertzian contacts in the partial slip regime. An FE three-dimensional Hertzian point contact model operating in the presence of spherical third bodies was developed. Both first bodies and third bodies were modeled as elastic–plastic materials. The effect of the third body particles on contact stresses and stick-slip behavior was investigated. The influence of the number of third body particles and material properties including modulus of elasticity, hardening modulus, and yield strength were analyzed. Fretting loops in the presence and absence of wear particles were compared, and the relation between the number of cycles and the hardening process was evaluated. The results indicated that by increasing the number of particles in contact, more load was carried by the wear particles which affect the wear-rate of the material. In addition, due to the high plastic deformation of the debris, the wear particles deformed and took a platelet shape. Local stick-slip behavior over the third body particles was also observed. The results of having wear debris with different material properties than the first bodies indicated that harder wear particles have a higher contact pressure and lower slip at the location of particles which affects the wear-rate.

Molecular Dynamics Simulations of Sliding Friction of Rigid Sphere with Single Crystal Copper Surface

2013 ◽  
Vol 345 ◽  
pp. 167-171 ◽  
Author(s):  
Xiao Jing Yang ◽  
Xiao Jiang Yang
Keyword(s):  
Single Crystal ◽  
Sliding Friction ◽  
Normal Force ◽  
Three Dimensional ◽  
Copper Surface ◽  
Friction Model ◽  
Rigid Sphere ◽  
Stick Slip ◽  
Friction Process ◽  
Single Crystal Copper

Using LAMMPS to establish the three-dimensional sliding friction model of the nanoscale diamond hemisphere with the single-crystal copper surface. Simulation and solving the process of sliding friction, research the micro-contact area atomic states change in sliding friction process, and study the friction characteristics change when the rigid sphere sliding on rough surface of the single crystal copper with minute projections. The results indicate that, in the sliding friction process, the lattice of substrate atoms are damaged under the forces of the extrusion which also cause corresponding dislocation and deformation. In the direction of the hemisphere movement, generate the pileup and side stream phenomena, and produce furrows. Friction and normal force rapidly increase with the depth of contact, and then enter into a stable sliding phase. For the thermal motion of atoms, formation of dislocations and the stick-slip effect, the curves of friction and normal force present waves of sawtooth. Small defect on surface of the substrate almost have no effect on the process of sliding friction.

scholarly journals Modelling elastic structures with strong nonlinearities with application to stick–slip friction

2014 ◽  
Vol 470 (2161) ◽  
pp. 20130593 ◽  
Author(s):  
Robert Szalai
Keyword(s):  
Point Contact ◽  
Linear Structure ◽  
Transformation Method ◽  
Friction Model ◽  
Contact Forces ◽  
Stick Slip ◽  
Lipschitz Continuous ◽  
Contact Points ◽  
Dimensional Equation ◽  
Low Dimensional

An exact transformation method is introduced that reduces the governing equations of a continuum structure coupled to strong nonlinearities to a low-dimensional equation with memory. The method is general and well suited to problems with isolated discontinuities such as friction and impact at point contact. It is assumed that the structure is composed of two parts: a continuum but linear structure and finitely many discrete but strong nonlinearities acting at various contact points of the elastic structure. The localized nonlinearities include discontinuities, e.g. the Coulomb friction law. Despite the discontinuities in the model, we demonstrate that contact forces are Lipschitz continuous in time at the onset of sticking for certain classes of structures. The general formalism is illustrated for a continuum elastic body coupled to a Coulomb-like friction model.

scholarly journals Laboratory Observations of Repeated Interactions between Ruptures and the Fault Bend Prior to the Overall Stick-Slip Instability Based on a Digital Image Correlation Method

2019 ◽  
Vol 9 (5) ◽  
pp. 933 ◽  
Author(s):  
Yan-Qun Zhuo ◽  
Yanshuang Guo ◽  
Sergei Alexandrovich Bornyakov
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Sampling Rate ◽  
Experimental Studies ◽  
Point Contact ◽  
Image Correlation ◽  
Spatiotemporal Evolution ◽  
Stick Slip ◽  
Temporal Sampling ◽  
Fault Bend

Fault geometry plays important roles in the evolution of earthquake ruptures. Experimental studies on the spatiotemporal evolution of the ruptures of a fault with geometric bands are important for understanding the effects of the fault bend on the seismogenic process. However, the spatial sampling of the traditional point contact type sensors is quite low, which is unable to observe the detailed spatiotemporal evolution of ruptures. In this study, we use a high-speed camera combined with a digital image correlation (DIC) method to observe ruptures during stick-slip motions of a simulated bent fault. Meanwhile, strain gages were also used to test the results of the DIC method. Multiple cycles of the alternative propagation of ruptures between the two fault segments on the both sides of the fault bend were observed prior to the overall failure of the fault. Moreover, the slip velocity and rupture speed were observed getting higher during this process. These results indicate the repeated interactions between the ruptures and the fault bend prior to the overall instability of the fault, which distinguishes the effect of the fault bend from the effect of asperities in straight faults on the evolution of ruptures. In addition, improvement in the temporal sampling rate of the DIC measurement system may further help to unveil the rupture evolution during the overall instability in future.

Elastohydrodynamic lubrication of a circular point contact for a compliant layered surface bonded to a rigid substrate Part 1: Theoretical formulation and numerical method

2000 ◽  
Vol 214 (3) ◽  
pp. 267-279 ◽  
Author(s):  
Z. M. Jin
Keyword(s):  
Numerical Method ◽  
Reynolds Equation ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Contact Radius ◽  
Rigid Substrate ◽  
Theoretical Formulation ◽  
Circular Point ◽  
Present Solution ◽  
Raphson Method

A full numerical analysis of the elastohydrodynamic lubrication problem of a circular point contact involving a compliant layered surface firmly bonded to a rigid substrate is reported in the present study. The Reynolds equation has been solved simultaneously with the full elasticity equation for the layered bearing surface under entraining motion, using the Newton-Raphson method. The theoretical formulation and the numerical method are presented in the present paper (Part 1), together with the comparison of the predicted minimum and central film thickness between the present solution when the contact radius is much smaller than the layer thickness and the results for a semi-infinite solid reported in the literature.

scholarly journals Transient analysis of isothermal elastohydrodynamic circular point contacts

2001 ◽  
Vol 215 (10) ◽  
pp. 1159-1172 ◽  
Author(s):  
D Jalali Vahid ◽  
H Rahnejat ◽  
Z M Jin ◽  
D Downson
Keyword(s):  
Transient Analysis ◽  
Solution Method ◽  
Numerical Solutions ◽  
Flat Glass ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
Good Qualitative Agreement ◽  
Circular Point ◽  
Good Agreement

In this paper a solution method is presented for the transient isothermal elastohydrodynamic lubrication of point contact conjunctions, based upon the Newton-Raphson scheme and low iteration relaxation. The numerical results are compared with the numerical and experimental observations of others for the circular point contact of a ball against a flat glass disc under oscillating conditions. Good agreement has been found with other numerical solutions. The comparison with the experimental results shows good qualitative agreement.

Stick-Slip Analysis of a Point Contact When a Body Contains Cylindrical Heterogeneities

2011 ◽  
Author(s):  
J. Leroux ◽  
D. Ne´lias
Keyword(s):  
Material Properties ◽  
Fiber Orientation ◽  
Point Contact ◽  
Numerical Procedure ◽  
Contact Pressure Distribution ◽  
Tangential Load ◽  
Stick Slip ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Cylindrical Inclusions

The stick-slip contact problem is investigated here when at least one of the contacting bodies contains inhomogeneous inclusions. Cylindrical inclusions with parallel axes are considered. The Eshelby’s equivalent inclusion method is used to solve the problem numerically. Interactions between close inclusions are taken into account in the numerical procedure, as well as the coupling between normal and tangential behaviours. It is found that the presence of heterogeneities in the vicinity of the surface contact affects the contact pressure, distribution and subsequently the distribution of shear traction and slip at the interface. The effects of the fiber orientation from the direction of the tangential load and different material properties would be presented.

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