Static grasping of a spherical object by two robot fingers is studied in this paper. The fingers may be rigid bodies or elastic beams, they may grasp the body with various orientation angles, and the tightening displacements may be linear or angular. Closed-form solutions for normal and tangential contact forces due to tightening displacements are obtained by solving compatibility equations, fo...

We describe in this paper two applications of Eulerian level set methods to fluid-structure problems arising in biophysics. The first one is concerned with three-dimensional equilibrium shapes of phospholipidic vesicles. This is a complex problem which can be recast as the minimization of the curvature energy of an immersed elastic membrane, under a constant area constraint. The second deals wi...

Motivated by recent experiments, we extend the Joanny-deGennes calculation of the elasticity of a contact line to an arbitrary contact angle and an arbitrary plate inclination in presence of gravity. This requires a diagonalization of the elastic modes around the nonlinear equilibrium profile, which is carried out exactly. We then make detailed predictions for the avalanche-size distribution at...

The mechanics of cells is strongly affected by molecular motors that generate forces in the cellular cytoskeleton. We develop a model for cytoskeletal networks driven out of equilibrium by molecular motors exerting transient contractile stresses. Using this model we show how motor activity can dramatically increase the network's bulk elastic moduli. We also show how motor binding kinetics natur...

Abstract. We model the coupled system formed by an incompressible, irrotational fluid and a nonlinear elastic body. We work with large displacement, small deformation elasticity (or St Venant elasticity), which makes the problem very interesting from the physical point of view. The elastic body is three-dimensional Ω ∈ R, and thus it can not be reduced to its boundary Γ (like in the case of a m...

2014 The magnetoelastic problem of a zig-zag 90° Bloch wall in iron is studied, either for a (110) or (001) wall. The elastic strains, due to magnetostriction, are calculated in both cases. The total energy of a zig-zag wall is obtained by adding, to the usual anisotropy and exchange contributions, the elastic term. Thus we find the equilibrium values for the periodicity and the angle of the zi...

Generalised Impedance P. ZOLTOWSKI and B. LEGAWIEC, J. Electroanal. Chem., 2004, 572, (2), 205–210 Transport of H in elastic metals has been analysed in terms of an impedance-like non-linear transfer function (TF). The equilibrium in a membrane was perturbed by application of a sinusoidal signal of concentrations of H, of large amplitude, to a surface. The fundamental harmonics of periodically ...

Thermodynamic analysis and molecular dynamics simulations were conducted to systematically study the size-dependent electrochemical response of solids. By combining the generalized Young-Laplace equation with the popular Butler-Volmer formulation, the direct influence of surface stress on solid film electrochemical reactions was isolated. A series of thermodynamic formulas were developed to des...

A low-energy electron microscopy study of two-dimensional Si~001! island shapes near thermal equilibrium on 10315 mm large single-domain terraces reveals a continuous increase of island aspect ratio and a shape transition from elliptical to ‘‘American-football’’-like with increasing island size. The size-dependent island shapes are driven by elastic relaxation caused by the intrinsic surface st...

We analyze the shape semiderivative of the solution to an asymptotic nonlinear adaptive elastic rod model, derived in Figueiredo and Trabucho [Math. Mech. Solids, 9 (2004), pp. 331–354], with respect to small perturbations of the cross section. The rod model is defined by generalized Bernoulli–Navier elastic equilibrium equations and an ordinary differential equation with respect to time. Takin...