The classical problem of rebound is usually treated by assuming that the colliding bodies are rigid and that the coefficient of friction, ~ , is constant. Two contact states can be distinguished: slidinq, in which the ratio of friction force to normal force is equal to ~ , and rolling, in which the friction force is zero. If sliding gives way to rolling during impact, the friction force will fa...

nanotechnology involves the ability to see and control individual atoms and molecules which are about 100 nanometer or smaller. one of the major tools used in this field is atomic force microscopy which uses a wealth of techniques to measure the topography and investigates the surface forces in nanoscale. friction force is the representation of the surface interaction between two surfaces an...

deep rolling is a kind of mechanical surface treatments that can improve surface quality, dimensional accuracy and mechanical properties of the parts. compressive residual stresses generated by the process reduce the tensile stresses during loading into the workpiece. the distribution of residual stress induced by deep rolling can be influenced by rolling parameters; such as overlap of the roll...

The incremental sheet metal forming (ISMF) process is a new and flexible method that is well suited for small batch production or prototyping. This paper studies the use of the finite element method in the incremental forming process of AA1050 sheets to investigate the influence of tool diameter, vertical step size, and friction coefficient on forming force, spring-back, and thickness distribut...

In this paper we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles. The model is based on a dynamic friction model developed previously for contact-point friction problems, called the LuGre model [1]. By assuming a contact patch between the tire and the ground we develop a partial differential equation for the distribution of the fr...

1. Three men and seven women, 25-40 yr of age, were asked to use the thumb and index fingers to grasp, lift, and hold the armature of a linear motor generating a 2.0-N opposing force (simulating an object weighing approximately 200 g) for 2 s. The surface in contact with the fingers was composed of smooth or polyamide plastic etched with 1.0-mm high Braille beads separated at 2.0- or 3.0-mm int...

ABSTRACT Dynamical friction arises from the interaction of a perturber and the gravitational wake it excites in the ambient medium. This interaction is usually derived assuming that the perturber has a constant velocity. In realistic situations, motion is accelerated as for instance by dynamical friction itself. Here, we study the effect of acceleration on the dynamical friction force. We chara...

If an admittance control law is properly designed, a workpiece can be guided into a fixture using only the contact forces for guidance (force-assembly). Previously, we have shown that: 1) a space of accommodation control laws that will ensure force-assembly without friction always exists, and 2) as friction is increased, a control law that allows force-assembly can be obtained as long as the fo...

In this paper, torsion extrusion (TE) process on 1050 aluminum alloy was investigated by simulation as a severe plastic deformation (SPD) method and the effects of friction coefficient, angular velocity of the rotating die and punch speed on maximum punch force were studied. A finite element (FE) model was developed to simulate the TE process via DEFORM software. The FE results were validated co...