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 ...

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...

In the Discrete Element modelling of soils, micromechanical behaviour at contacts has often been considered to have a minor influence on macromechanical response, leaving basic theoretical models (e.g., Hertz) describe contact response in normal direction. A realistic description may be crucial especially when investigating small strain ranges. Recent experimental inter-particle loading tests g...

Gear’s normal contact stiffness played an important role in the mechanical equipment. In this paper, the M-B fractal model is modified and the contact surface coefficient is put forward to set up the fractal model, considering the influence of friction, which could be used to calculate accurately the involute arc cylindrical gears’ normal contact stiffness based on the fractal theory and Hertz ...

In a recent Letter, Persson [1] suggested a new model of contact between arbitrary randomly rough surfaces. He considered also fractal surfaces which he characterized above the lower cutoff only by their dimension Df and an additional constant. He argued that in the framework of the model, the area of real contact A in most cases is proportional to the load P. However, there are examples which ...