This paper introduces an experimental technique to investigate dynamic friction characteristics of sliding interfaces at normal pressures up to 125 MPa, slip speeds up to 15 m/s and slip distances of approximately 10 mm. This new apparatus involves a novel modification of the conventional torsional Kolsky bar apparatus employed extensively in the past to investigate high-strain-rate behavior of...

The transition from stick to slip at a dry frictional interface occurs through the breaking of microjunctions between the two contacting surfaces. Typically, interactions between junctions through the bulk lead to rupture fronts propagating from weak and/or highly stressed regions, whose junctions break first. Experiments find rupture fronts ranging from quasistatic fronts, via fronts much slow...

We present a new three-dimensional inventory of the southern San Francisco Bay area faults and use it to calculate stress applied principally by the 1989 M = 7.1 Loma Prieta earthquake and to compare fault seismicity rates before and after 1989. The major high-angle right-lateral faults exhibit a different response to the stress change than do minor oblique (right-lateral/thrust) faults. Seismi...

This paper describes experimental and numerical procedures to estimate friction torque on a rotating shaft due to radial elastomeric seals. Two different test rigs have been built, in order to highlight the relationship between the overall friction and the local behaviour of each lip portion in presence of dynamic eccentricities. A direct measurement has been performed with a rotating shaft mac...

Abstract— Ironically, despite the growing familiarity with composite materials and ever-increasing range of applications, use of natural fibers as reinforcement in polymeric composites for technical application has been a research subject of scientist. Pineapple leaf fibre (PALF) is one of them that have also good potential as reinforcement in polymer composite. In this present work, an experim...

We measure the spatial and temporal behavior of the true contact area A along a rough spatially extended interface between two blocks in frictional contact. Upon the application of shear the onset of motion is preceded by a discrete sequence of cracklike precursors, which are initiated at shear levels that are well below the threshold for static friction. These precursors arrest well before tra...

The critical rheology of sheared frictional granular materials near jamming transition is numerically investigated. It is confirmed that there exists a true critical density which characterizes the onset of the yield stress and two fictitious critical densities which characterize the scaling laws of rheological properties. We find the existence of a hysteresis loop between two of the critical d...

We show that in slowly generated two-dimensional packings of frictional spheres, a significant fraction of the friction forces lie at the Coulomb threshold-for small pressure p and friction coefficient mu , about half of the contacts. Interpreting these contacts as constrained leads to a generalized concept of isostaticity, which relates the maximal fraction of fully mobilized contacts and cont...