Aging in freely evolving granular gas with impact velocity dependent coefficient of restitution

2018 ◽  
Author(s):  
Shikha Kumari ◽  
Syed Rashid Ahmad
Keyword(s):  
Impact Velocity ◽  
Coefficient Of Restitution ◽  
Granular Gas

Analytical Study of the Oblique Impact of a Rod with a Flat Using an Elasto-Plastic Contact Model

2015 ◽  
Vol 801 ◽  
pp. 25-32
Author(s):  
Ozdes Cermik ◽  
Hamid Ghaednia ◽  
Dan B. Marghitu
Keyword(s):  
Impact Velocity ◽  
Contact Force ◽  
Analytical Study ◽  
Initial Conditions ◽  
Permanent Deformation ◽  
Oblique Impact ◽  
Coefficient Of Restitution ◽  
Contact Model ◽  
Impact Angles ◽  
The Impact

In the current study a flattening contact model, combined with a permanent deformation expression, has been analyzed for the oblique impact case. The model has been simulated for different initial conditions using MATLAB. The initial impact velocity used for the simulations ranges from 0.5 to 3 m/s. The results are compared theoretically for four different impact angles including 20, 45, 70, and 90 degrees. The contact force, the linear and the angular motion, the permanent deformation, and the coefficient of restitution have been analyzed. It is assumed that sliding occurs throughout the impact.

A-9 Effect of Impact Velocity on Bat-Ball Coefficient of Restitution of Metal Baseball Bat

2014 ◽  
Vol 2014 (0) ◽  
pp. _A-9-1_-_A-9-5_ ◽  
Author(s):  
Yutaka KOBAYASHI ◽  
Fumiya OMI ◽  
Kenichi TOKIEDA ◽  
Seishi FUJIHARA ◽  
Kazuyoshi ARAI
Keyword(s):  
Impact Velocity ◽  
Coefficient Of Restitution

Elasto-Plastic Impact on Auxetic/Metal Foams

2020 ◽  
Vol 87 (12) ◽  
Author(s):  
N. Kumar ◽  
S. N. Khaderi ◽  
K. Tirumala Rao
Keyword(s):  
Energy Dissipation ◽  
Impact Velocity ◽  
Poisson’S Ratio ◽  
Metal Foam ◽  
Coefficient Of Restitution ◽  
Peak Force ◽  
Poisson's Ratio ◽  
Rigid Sphere ◽  
Yield Strain ◽  
Maximum Displacement

Abstract We investigate the normal impact of a rigid sphere on a half-space of elasto-plastic auxetic/metal foam using the finite element method. The dependence of the coefficient of restitution, peak force, maximum displacement, and contact duration on the yield strain, impact velocity, and elastic and plastic Poisson’s ratio is analyzed. For a given elastic Poisson’s ratio, the coefficient of restitution generally decreases with an increase in the plastic Poisson’s ratio and impact velocity. When the plastic Poisson’s is maintained constant, the coefficient of restitution increases with an increase of the elastic Poisson’s ratio. These trends are explained using plastic energy dissipation. The energy dissipation trends are further investigated by decomposing it into deviatoric and hydrostatic parts. For a given impact velocity, the peak force is relatively insensitive to most of the elastic and plastic Poisson’s ratio combinations. We also show that for the cases where the elastic and plastic Poisson’s ratios are equal, the coefficient of restitution is relatively insensitive to their actual values. These findings can guide researchers to identify the right elastic and plastic Poisson’s ratio combinations so that lattice materials with exceptional energy absorbing capacity can be designed using topology optimization.

A Novel Optical Technique for Measuring the Coefficient of Restitution of Microparticle Impacts in a Forced Flowfield

2012 ◽  
Author(s):  
C. J. Reagle ◽  
J. M. Delimont ◽  
W. F. Ng ◽  
S. V. Ekkad ◽  
V. P. Rajendran
Keyword(s):  
Impact Velocity ◽  
Fundamental Property ◽  
Impact Angle ◽  
Coefficient Of Restitution ◽  
304 Stainless Steel ◽  
Wall Material ◽  
Free Jet ◽  
Stainless Steel Coupon ◽  
Novel Method ◽  
Impact Angles

Erosion and deposition in gas turbine engines are functions of particle/wall interactions and Coefficient of Restitution (COR) is a fundamental property of these interactions. COR depends on impact velocity, angle of impact, temperature, particle composition, and wall material. The current study attempts to characterize the fundamental behavior of sand at different impact angles. A PIV system is used in the Virginia Tech Aerothermal Rig to measure velocity trajectories of microparticles. A novel method is used that solves for impact velocity in a forced flowfield by numerical methods. Two sizes of Arizona Test Dust and one of Glass beads are impacted into a 304 Stainless Steel coupon. Free jet velocity is 27m/s at room temperature. Impact angle varies from almost 90 to 25 degrees depending on particle. Mean results compare favorably with trends established in literature. This utilization of this technique to measure COR of microparticle sand will help develop a computational model and serve as a baseline for further measurements at elevated, engine representative air and wall temperatures.

Impact Crushing and Rebound of Thin-Walled Hollow Spheres

2013 ◽  
Vol 535-536 ◽  
pp. 40-43 ◽  
Author(s):  
Rong Hao Bao ◽  
T.X. Yu
Keyword(s):  
Impact Velocity ◽  
Analytical Modeling ◽  
Hollow Spheres ◽  
Rigid Wall ◽  
Coefficient Of Restitution ◽  
Dynamic Responses ◽  
Relative Thickness ◽  
Thin Walled ◽  
Impact Crushing ◽  
The Impact

The dynamic behavior of a thin-walled hollow sphere colliding onto a rigid wall has been studied by experiments, numerical simulation and analytical modeling, as reported in our previous papers. In the present paper, the impact crushing of metallic thin-walled hollow spheres onto rigid plates and the subsequent rebound are analyzed using finite element method. The effects of hollow sphere’s thickness-to-radius ratio, the material properties and the impact velocity on the dynamic responses are systematically investigated. The transition from axisymmetric dimpling to non-axisymmetric lobing is found to depend on the relative thickness of spheres and impact velocity; while the coefficient of restitution almost merely depends on impact velocity.

Coefficient of Restitution for Collinear Collisions of Elastic-Perfectly Plastic Spheres

1997 ◽  
Vol 64 (2) ◽  
pp. 383-386 ◽  
Author(s):  
C. Thornton
Keyword(s):  
Theoretical Model ◽  
Analytical Solution ◽  
Yield Stress ◽  
Impact Velocity ◽  
Contact Interaction ◽  
Material Properties ◽  
Coefficient Of Restitution ◽  
Normal Contact ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Based on a simplified theoretical model for the normal contact interaction of two elastic-perfectly plastic spheres, an analytical solution is provided for the coefficient of restitution. The solution is expressed in terms of the ratio of impact velocity to yield velocity rather than in terms of material properties such as the yield stress which is difficult to reliably ascertain for many materials.

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