During underground nuclear tests, rocks may fail by plastic yielding, which limits shear strength, or by tensile fracture, wherever maximum principal stress exceeds tensile strength. A third mode of failure exists due to friction along closed fractured surfaces. There, friction affects slipping and can thus limit stress. In this paper, we study the effect of friction on the simulated dynamic re...

This survey is devoted to the significant role of various dry friction laws in engineering sciences. Both advantages and disadvantages of a frictional process are illustrated and discussed, but excluding the nature of friction. It is shown how the classical friction laws and modern friction theories exist in today’s pure and applied sciences. Static and dynamic friction models are described. An...

Liquid water is pushed through flow channels of fuel cells, where one surface is a porous carbon electrode made up of carbon fibers. Water drops grow on the fibrous carbon surface in the gas flow channel. The drops adhere to the superficial fiber surfaces but exhibit little penetration into the voids between the fibers. The fibrous surfaces are hydrophobic, but there is a substantial threshold ...

An instrument for noncontact measurement of differential vibrations is developed, based on the self-mixing interferometer. As no reference arm is available in the self-mixing configuration, the differential mode is obtained by electronic subtraction of signals from two (nominally equal) vibrometer channels, taking advantage that channels are servo stabilized and thus insensitive to speckle and ...

This paper aims at studying the effect of uncertain parameters on a two-link planar manipulator using a fuzzy logic approach. The uncertain parameters are modeled as fuzzy variables and the dynamic simulation of the robot is performed using fuzzy dynamic analysis. Two case studies are considered to analyze the dynamic behavior of the robot manipulator: a) uncertain payload and b) uncertain payl...

Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced...

This paper proposes a nonlinear observer for an electropneumatic clutch actuator. Parameter estimation of the clutch load characteristic and friction are also treated through adaptation. Estimates of piston velocity, chamber pressures and dynamic friction state are made based on piston position measurement only. Persistence of excitation conditions for convergence of the estimation error are de...

This paper investigates the holdup problem in the dynamic search market where buyers and sellers search for their trading partners and specific investments are made after match but before trade. We show that frictionless (competitive) market imposes severe limitations on attainable efficiencies: Markets with small friction make the holdup problem more serious than those with large friction beca...

dynamic behavior of the wind-excited-benchmark-building using semi-active electromagnetic friction dampers (saemfds), with modulated homogeneous friction algorithm is presented. the performance of the benchmark building is studied under across wind loads by installing the saemfds with smooth boundary layer semi-active friction (sblsaf) algorithm. the governing equations of motion are solved by ...

Submitted for the MAR05 Meeting of The American Physical Society Preparation and Friction Property of Dendritic Thin Film QING ZHANG, LYNDEN ARCHER, Cornell University — To investigate the effect of film structure on their friction properties, thin films with dendritic structure were prepared on silicon surfaces by step-growth propagation, and their friction properties were studied by AFM. The ...