The paper addresses rigid body dynamic simulation of mechanical systems with frictional contacts. It is well known that the use of Coulomb's law of friction with the principles of classical rigid body dynamics introduces mathematical inconsistencies. Speciically, the initial value problem may have no solutions or more than one solution. We show that a suitable lumped model of compliance in the ...

UNLABELLED BackgroundAcquired alopecia of the lower legs may occur secondary to friction due to socks, footwear, or both on the lower extremities. There is scant literature that reports on this phenomenon.Methods and MaterialsWe describe 5 patients who presented with alopecia of their lower legs induced by socks, footwear, or both. METHODS AND MATERIALS We reviewed PubMed for the following te...

We have studied the variation of frictional force with externally applied load for a Pt-coated atomic force microscope tip in contact with the surface of mica cleaved in ultrahigh vacuum. At low loads, the frictional force varies with load in almost exact proportion to the area of contact as predicted by the Johnson-KendallRoberts ( JKR) theory [K. L. Johnson, K. Kendall, and A. D. Roberts, Pro...

Rate-and-state friction is an empirical approach to the behavior of a frictional surface. We use a nematic liquid crystal in a channel between two parallel planes to model frictional sliding. Nematic liquid crystals model a wide variety of physical phenomena in systems that rapidly switch between states; they are well studied and interesting examples of anisotropic non-Newtonian fluids, charact...

Frictional interfaces abound in natural and man-made systems, yet their dynamics are not well-understood. Recent extensive experimental data have revealed that velocity-strengthening friction, where the steady-state frictional resistance increases with sliding velocity over some range, is a generic feature of such interfaces. This physical behavior has very recently been linked to slow stick-sl...

The peak and critical state strengths of sands are linearly related to the stress level, just as the frictional resistance to sliding along an interface is related to the normal force. The analogy with frictional sliding has led to the use of a 'friction angle' to describe the relationship between strength and stress for soils. The term 'friction angle' implies that the underlying mechanism is ...

[1] We report on laboratory experiments examining the frictional and hydrologic properties of fault gouge and wall rock along a borehole transect that crosses a major out-of-sequence thrust splay fault within the Nankai accretionary complex. At 25 MPa effective normal stress, the fault zone material is frictionally weak (m 0.44) and exhibits low permeability after shearing (k < 5.5 10 20 m). Fa...

The dynamic interplay between static and sliding friction is fundamental to many animal movements. One interesting example of stick-slip friction is found in the sound-producing apparatus of many spiny lobster species (Palinuridae). The acoustic movements of the spiny lobster's plectrum over the file are generated by stick-slip friction between the two surfaces. We examined the microscopic anat...