A contact/friction isoparametric finite element for the analysis of connections between laminated composite plates is presented. The element is compatible with a three-dimensional plate element based on layer-wise constant shear theory. The contact/friction element is based on a simple regularization of the unilateral contact with an orthotropic Coulomb friction problem. Two different friction ...

Two experiments were performed to determine the effects of friction and needle geometry during robotic needle insertion into soft tissues. In Experiment I, friction forces along the instrument axis were characterized during needle insertion into bovine liver under CT fluoroscopic imaging. Because the relative velocity of the tissue and needle affect viscous and Coulomb friction, the needle inse...

The 2D-Signorini contact problem with Tresca and Coulomb friction is discussed in infinitedimensional Hilbert spaces. First, the problem with given friction (Tresca friction) is considered. It leads to a constraint non-differentiable minimization problem. By means of the Fenchel duality theorem this problem can be transformed into a constrained minimization involving a smooth functional. A regu...

The interfacial structure/property relationships of a representative composite system consisting of SIC (SCS-6) fibers in a T&Al + Nb intermetallic alloy have been investigated. Two samples were fabricated at 1040°C with different exposure times in order to vary the amount of fiber-matrix reaction. This resulted in samples with reaction zone thicknesses (S) of 1.1 and 1.7pm, while ensuring roug...

The stiffness of micron-sized sphere-plate contacts was studied by employing high frequency, tangential excitation of variable amplitude (0-20 nm). The contacts were established between glass spheres and the surface of a quartz crystal microbalance (QCM), where the resonator surface had been coated with either sputtered SiO2 or a spin-cast layer of poly(methyl methacrylate) (PMMA). The results ...

A globally exponentially stable speed observer for mechanical systems was recently reported in the literature, under the assumptions of known (or no) Coulomb friction and no disturbances. In this note we propose and adaptive version of this observer, which is robust vis–à–vis constant disturbances. Moreover, we propose a new globally convergent speed observer that, besides rejecting the disturb...

Abstract. We discuss the advantages and results of using a mixing-length, compressible model to account for shear banding behaviour in granular flow. We formulate a general approach based on two function of the solid fraction to be determined. Studying the vertical chute flow, we show that shear band thickness is always independent from flowrate in the quasistatic limit, for Coulomb wall bounda...

identification of damping parameter is usually more complicated and unreliable comparing to mass or stiffness identification in structural dynamics. there are many factors such as intermolecular friction, coulomb friction and viscous damping affecting the damping mechanisms in a structure. therefore it is difficult, and in some cases impossible, to describe the details of damping mechanisms by ...