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 ...

This study evaluated the effects of physical characteristics and geologic factors on the shear strength of compacted sands from Wisconsin that are used as granular backfill for mechanically stabilized earth walls and reinforced soil slopes. Physical properties and shear strength were determined for 30 compacted sands collected from a broad range of geological deposits. Relationships between str...

in this article, the size, dimensions, volume, bulk and particle densities, empyting and filling angles of repose and friction coefficients against different surfaces were evaluated for two varieties of barley, sahra and valfajr, as a function of moisture content in the range of 10.12 to 42.17 (w.b.%). most physical properties of barley varieties were significantly affected by moisture content ...

The friction coefficient is an important parameter in designing magnetic tape transports. We have introduced laser surface texturing to reduce the friction coefficient between guides and magnetic tape. The surface features enhance the formation of an air bearing and hence, reduce the friction coefficient. INTRODUCTION Lateral tape motion (LTM) is defined as the time-dependent motion of the tape...

We have studied friction and dissipation in single and bilayer graphene films grown epitaxially on SiC. The friction on SiC is greatly reduced by a single layer of graphene and reduced by another factor of 2 on bilayer graphene. The friction contrast between single and bilayer graphene arises from a dramatic difference in electron-phonon coupling, which we discovered by means of angle-resolved ...

b = a length L c = the cohesion intercept M L T Ip = the plasticity index P = a force M L T u = the pore fluid pressure ML T θ = an angle Angle μ1 = shear strength reduction factor related to time effects μ2 = shear strength reduction factor related to fissuring σ = the normal stress on a plane M L T τ = the shearing stress on a plane M L T φ = the angle of internal friction Angle ψ = an angle ...

A novel observer structure for vehicle side slip angle (β ) estimation is proposed, in which a local approximation of the nonlinear tire model is adopted. Fuzzy logic approach is adopted to combine the local observer models so as to deal with the nonlinear nature of vehicle dynamics. The derivation of observer’s state equations and the estimation mechanism is developed. By choosing the membersh...

We report the first measurements of friction angles for a naturally formed gravel streambed. For a given test grain size placed on a bed surface, friction angles varied from 10" to over 100'; friction angle distributions can be expressed as a function of test grain size, median bed grain size, and bed sorting parameter. Friction angles decrease with increasing grain size relative to the median ...

Direct tyre-road contact friction estimation is essential for future active safety systems. Friction estimation methods were proposed earlier for driving conditions in the presence of a slip angle or slip ratio. However, the estimation of friction from a freely rolling tyre is still an unsolved topic. This study uses three 3-axis accelerometers on the inner liner of a tyre to detect friction po...

Using frictional force microscopy (FFM), the friction surface characteristics were compared between twisted nematic (TN) mode and vertical alignment (VA) mode alignment films (AFs). The friction asymmetry was detected depending on temperature conditions on TN mode AF, but not on VA mode AF. The difference between two modes was explained by leaning intermolecular repulsion caused by the pre-tilt...