In this paper, a DEM (Discrete Element Method) model is presented and a series of computer experiments is analyzed and compared to experimental validations. Also, the simulations are compared to experimental results. The model uses a 3 parameter contact force to calculate impact between particles and other object such as vanes. The components of the contact forces are typically modeled in terms...

rails fracture by the growth of fatigue crack or critical crack is one of the prevalent defects in railway. the rail fracture, failure and stress analysis should be studied in order to prevention of rail fracture. in this paper, new formulation of contact stress for two rolling bodies is presented, where the results are closed to the hertz stress formulation. moreover, stress analysis is done b...

in the present research, in contrast to the available papers, not only the superelasticity but also the shape memory effects are taken into account in determination of the impact responses. at the same time, in addition to modifying brinson’s model for the shape memory alloys (smas), to include new parameters and loading events, and hertz contact law, distributions of the sma phases are conside...

In this paper, the nonlinear dynamic response of deep groove ball bearings with clearance was studied numerically. The imperfect connections raceways and rolling balls were established by contact elements. order to describe characteristics accurately, a hysteresis damping coefficient introduced into Hertz model, which represented dissipative term during contact–impact process. tangential force ...

The area of contact between two objects was detected by using the strong enhancement of the fluorescence of rigidochromic probe molecules attached to one of the surfaces. Confinement of the molecules suppresses nonradiative decay and turns on the fluorescence. The approach is demonstrated by imaging of the contact area of a plastic sphere in contact with a flat glass surface. Our results agree ...

UNLABELLED Viscoelastic deformation of the contact volume between adhering bacteria and substratum surfaces plays a role in their adhesion and detachment. Currently, there are no deformation models that account for the heterogeneous structure and composition of bacteria, consisting of a relatively soft outer layer and a more rigid, hard core enveloped by a cross-linked peptidoglycan layer. The ...

The peak forces exerted on soft and rigid samples by a force microscope have been modeled by performing numerical simulations of the tip motion in liquid. The forces are obtained by using two contact mechanics models, Hertz and Tatara. We present a comparison between the numerical simulations and three analytical models for a wide variety of probe and operational parameters. In general, the for...

Electro-mechanical actuators including planetary roller screw (PRS) support cyclic loads in aeronautical conditions. PRS multiple thread contacts between screw, rollers and nut allow the mechanism to large loads. However, accreditation requires fine prediction of fatigue lifespan. In this paper, a design strategy for mechanisms is proposed combining Hertz contact model multi-axial criterion. Th...