The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum...

Flexure occurs on intermediate geologic timescales (∼1 Myr) due to volcanic-island building at the Island of Hawaii, and deformational response lithosphere is simultaneously elastic, plastic, ductile. At shallow depths low temperatures, elastic deformation transitions frictional failure faults where stresses exceed a threshold value, this complex rheology controls rate manifested by earthquakes...

[1] A central problem in studies of fault interaction and earthquake triggering is that of quantifying changes in frictional strength and the constitutive response caused by dynamic stressing. We imposed normal stress vibrations on creeping laboratory shear zones to investigate the process of dynamic weakening and the conditions under which resonant frictional behavior occurs. Layers of quartz ...

This paper describes statistical determination of fretting-induced failure of an electro-deposited coating. A fretting test is conducted using a ball-on-flat plate configuration. During a test, a frictional force is measured, along with the relative displacement between an AISI52100 ball and a coated flat specimen. Measured data are analyzed with statistical process control tools; a frictional ...

Shear thickening in dense particulate suspensions was recently proposed to be driven by the activation of friction above an onset stress needed to overcome repulsive forces between particles. Testing this scenario represents a major challenge because classical rheological approaches do not provide access to the frictional properties of suspensions. Here we adopt a different strategy inspired by...

Frictional and frictionless granular materials in a split-bottom ring shear cell geometry show wide shear bands under slow, quasi-static deformation. Here, the differences between frictional and frictionless materials are elaborated using discrete element simulations (DEM). Several continuum fields like the density, the velocity field, the deformation gradient and the stress are used here for c...

INTRODUCTION The aim of this study was to evaluate the frictional forces generated by 4 types of passive stainless steel self-ligating brackets (SLBs) and by nonconventional elastomeric ligatures (NCEL) and conventional elastomeric ligatures (CEL) during sliding mechanics. METHODS An experimental model consisting of 5 aligned stainless steel 0.022-in brackets was used to assess frictional for...

The dynamic evolution with frictional contact of a viscoelastic body is considered. The assumptions on the functions used in modelling the contact are broad enough to include both the normal compliance and the Tresca models. The friction law uses a friction coefficient which is a non-monotone function of the slip. The existence and uniqueness of the solution are proved in the general three-dime...