We consider the problem of planning manipulation tasks in which rigid body dynamics are significant and the rigid bodies undergo frictional contacts. We develop a dynamic model with frictional compliant contacts, and a time-stepping algorithm that lends itself to finding trajectories with constraints on the starting and goal conditions. Because we explicitly model the local compliance at the co...

Abstract-Following the idea of Bowie and Freese we consider a crack in a field of pure bending. The crack is closed over part of its extent, and the two crack faces in contact are allowed to slip under frictional constraints. The solution is constructed under the assumption that the applied loading is monotonically increased. It is discovered, however, that it is possible to analyze unloading b...

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...

We consider numerical approximations of a class of abstract nonlinear evolutionary systems arising in the study of quasistatic frictional contact problems for elastic-viscoplastic materials. Both spatially semi-discrete and fully discrete schemes are analyzed with the nite element method employed to discretize the spatial domain. Strong convergence of both approximations is established under mi...

It is generally assumed that fingerprints improve the grip of primates, but the efficiency of their ridging will depend on the type of frictional behaviour the skin exhibits. Ridges would be effective at increasing friction for hard materials, but in a rubbery material they would reduce friction because they would reduce contact area. In this study we investigated the frictional performance of ...

In this paper we define a class of mechanical systems consisting of rigid objects (defined by linear or quadratic surface patches) connected by frictional contact linkages between surfaces. (This class of mechanisms is similar to the Analytical Engine developed by Babbage in 1800s except that we assume frictional surfaces instead of toothed gears.) We prove that a universal Turing Machine (TM) ...

The microstructure investigated in this study was inspired by the anisotropic microornamentation of scales from the ventral body side of the California King Snake (Lampropeltis getula californiae). Frictional properties of snake-inspired microstructured polymer surface (SIMPS) made of epoxy resin were characterised in contact with a smooth glass ball by a microtribometer in two perpendicular di...

Understanding the dynamics of frictional motion is essential to fields ranging from nano-machines to the study of earthquakes. Frictional motion involves a huge range of time and length scales, coupling the elastic fields of two blocks under stress to the dynamics of the myriad interlocking microscopic contacts that form the interface at their plane of separation. In spite of the immense practi...