Deformation of the material during cyclic expansion extrusion (CEE) is investigated using upper-bound theorem. The analytical approximation of forming loads agrees very well with the FEM results for different amounts of chamber diameter, friction factor and also for lower die angles. However, the difference between analytical and numerical solution increases at higher die angles which are expla...

Flowability - as measured by hopper discharge rate, angle of repose and Carr's index (CI) - of surface modified microcrystalline cellulose granules was investigated experimentally. Three-dimensional simulations of the granule flow were performed, using the discrete element method (DEM), including either sliding and rolling friction or sliding friction and cohesion in the model. Granule surface ...

Abrasive flow polishing plays an important part in modern ultra-precision machining. Ultrafine particles suspended in the medium of abrasive flow removes the material in nanoscale. In this paper, three-dimensional molecular dynamics (MD) simulations are performed to investigate the effect of impacting direction on abrasive cutting process during abrasive flow polishing. The molecular dynamics s...

The motion of a ruck in a rug is used as an analogy to explain the role of dislocations in crystalline solids. We take literally one side of this analogy and study the shape and motion of a bump, wrinkle or ruck in a thin sheet in partial contact with a rough substrate in a gravitational field. Using a combination of experiments, scaling analysis and numerical solutions of the governing equatio...

Friction stir processing (FSP) has been developed on the principles of friction stir welding (FSW) as an effective and efficien new method for grain refinement and microstructural modification, providing intense plastic deformation as well as higher strain rates than other conventional severe plastic deformation methods. FSP produces an equiaxed homogeneous microstructure consisting of fine gra...

failure of the quay walls due to earthquakes results in severe economic loss. because of hazards threatening such inexpensive nodes of national and international transportation networks, seismic design of quay walls is still an evolving topic in marine structural engineering. this study investigates the sensitivity of the gravity-type quay wall stability respect to uncertain soil and seismic pr...

This paper presents an investigation on mechanism of the inclined 1 cone penetration test (CPT) using the numerical discrete element method (DEM). 2 A series of penetration tests with the penetrometer inclined at different angles 3 (i.e., 0°,15°, 30°, 45° and 60°) were numerically performed under µ=0.0 and 4 µ=0.5, where µ is the frictional coefficient between the penetrometer and the soil. 5 T...

Nowadays the surface texturing has been widely recognized as a usable capability to improve the tribological systems. In this paper, ultrasonic assisted turning (UAT) isperformed to create the micro textures on the flat faces. Micro surface texturing ismade on the Al7075-T6 by the UAT in the face turning process. Then, the influences of cutting speed feed, vibration direction and vibration ampl...

Recent experiments on protein-folding dynamics have revealed strong evidence for internal friction effects. That is, observed relaxation times are not simply proportional to the solvent viscosity as might be expected if the solvent were the only source of friction. However, a molecular interpretation of this remarkable phenomenon is currently lacking. Here, we use all-atom simulations of peptid...

A simple model is developed that predicts the coefficient of rolling friction for an undriven laboratory cart on a track that is approximately independent of the mass loaded onto the cart and of the angle of inclination of the track. The model includes both deformation of the wheels/track and frictional torque at the axles/bearings. The concept of rolling friction is contrasted with the static ...