In forming processes contact friction significantly influence metal flow, stress-strain state and process parameters. Furthermore, tribological conditions influence workpiece surface quality and its dimensional precision. This paper presents research results of the influence of contact friction coefficient on a workpiece surface quality in ring upsetting by flat plates. Workpiece surface roughn...

Marine-gel biopolymers were recently visualized at the molecular level using atomic force microscopy (AFM) to reveal fine fibril-forming networks with low to high degrees of cross-linking. In this work, we use force spectroscopy to quantify the intra- and intermolecular forces within the marine-gel network. Combining force measurements, AFM imaging, and the known chemical composition of marine ...

The force between two parallel charged flat surfaces, with discrete surface charges, has been calculated with Monte Carlo simulations for different values of the electrostatic coupling. For low electrostatic coupling (small counterion valence, small surface charge, high dielectric constant, and high temperature) the total force is dominated by the entropic contribution and can be described by m...

A continuum mechanical theory of fracture without singular fields is proposed. The primary contribution is the rationalization of the structure of a ‘law of motion’ for crack-tips, essentially as a kinematical consequence and involving topological characteristics. Questions of compatibility arising from the kinematics of the model are explored. The thermodynamic driving force for crack-tip moti...

Abstract The forming history influences the mechanical properties and formability of sheet metals. Numerous models approaches have been published to implement this influence into FE-tools, based on isotropic damage or failure criterions. In paper, a uniaxial pre-forming change in loading direction material parameters is investigated for two different steel grades tensile tests. It was found, th...

The study based on the slab method and FEM simulation is to explore wire rod drawing using rotating die. Constant shear friction assumed at interface between die different conditions such as angular velocity (ω), half angle (α°), frictional factor (m) etc. influence of forming characteristics. Besides, stress occurred has been analyzed realize whether failed or not. axial stress, radial force, ...

High hardening of the steel, which is caused by martensitic transformation through cold forming, leads to significant local elastic roll deformation (flattening). The rolling strain-hardened steel requires higher forces and torques, result in high force. Roll flattening can be reduced using rolls made a material with significantly modulus elasticity. suitability ceramic materials for modern hot...

We show that the number of concentric graphene cylinders forming a carbon nanotube can be found by squeezing the tube between an atomic force microscope tip and a silicon substrate. The compressed height of a single-walled nanotube (double-walled nanotube) is approximately two (four) times the interlayer spacing of graphite. Measured compression forces are consistent with the predicted bending ...

Talin plays a key role in the assembly and stabilisation of focal adhesions, but whether it is directly involved in force transmission during morphogenesis remains to be elucidated. We show that the traction force of Dictyostelium cells mutant for one of its two talin genes talB is considerably smaller than that of wild-type cells, both in isolation and within tissues undergoing morphogenetic m...

www.sciencemag.org SCIENCE VOL 331 18 FEBRUARY 2011 811 COVER False-colored atomic force micrograph of two types of molecules forming a mixed self-assembled monolayer on a gold surface. The two molecules differ in height by 0.2 nanometers, giving the appearance of ripples. This image was awarded fi rst place in the photography category in the 2010 Science/NSF International Science & Engineering...