Verifying the tangential and normal restitution coefficients for double-sphere particles

• Published in: Powder technology 2020-03, Vol.363, p.419-427
• Main Authors: Zhang, Shen, Gui, Nan, Huang, Xiaoli, Ge, Liang, Yang, XingTuan, Tu, Jiyuan, Jiang, Shengyao
• Format: Article
• Language: English
• Subjects: Coefficient of restitution; Coefficients; Collision dynamics; Double-sphere; High speed cameras; Non-spherical particle; Particle; Restitution; Rigid body; Rigid structures
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2020.01.025

The collision between a single-sphere and a double-sphere is measured in this study by a high speed camera to verify the fundamental issue of tangential and normal restitution coefficients for a particular shape of double-sphere. In this experiment, a single-sphere moves and collides on a stationary double-sphere, and a high speed camera is used to capture the collision of them. Numerous tests were performed by varying the pre-collisional inclinations and pre-collisional velocities of the single-sphere. Two different definitions of the kinematic coefficient of restitutions, both normal and tangential, have been scrutinized by the experimental data to see which one is realistically true or reasonable. After comparison, the contact-point (surface) based definition is the right one which has almost case-independent value for the restitution coefficient, either in the normal or tangential direction. This verifies a key point which would be very useful for modeling the rigid body collisions, either spherical or non-spherical. [Display omitted] •For spheres, normal & tangential coefficients of restitution (COR) are constants.•For non-spherical (NS), only COR defined by contact point's velocities is correct.•For NS, it is incorrect to define COR by post- & pre- velocities of mass centroids•Correct COR definition is independent of velocity, inclination, & particle shape.•Tangential COR also exists for NS although it has a negative constant value.