We report on the first three-dimensional hydrodynamic simulations of secular and dynamical nonaxisymmetric instabilities in collapsing, rapidly rotating stellar cores which extend well beyond core bounce. The resulting gravitational radiation has been calculated using the quadrupole approximation. We find that secular instabilities do not occur during the simulated time interval of several 10ms...

A shape sensitive, variational approach for the matching of surfaces considered as thin elastic shells is investigated. The elasticity functional to be minimized takes into account two different types of nonlinear energies: a membrane energy measuring the rate of tangential distortion when deforming the reference shell into the template shell, and a bending energy measuring the bending under th...

Analysis of reciprocating equipment piston rod leads to nonlinear elastic-plastic deformation analysis of rod with initial imperfection under axial dynamic load. In this paper a new and effective model and analytical formulations are presented to evaluate dynamic deformation and elastic-plastic stresses of reciprocating machine piston rod. This new method has capability to account for geometric...

A nonlinear surface registration algorithm of thoracic/abdominal structures segmented from CT and PET volumes is presented. The aim of this work is to develop a method that can provide an initial estimate of the elastic deformation between the images, so that MI-based techniques can be successfully applied. To perform the matching, a Bspline Free Form Deformation (FFD) model has been chosen. Hi...

Synthetic approaches to prepare designer materials that localize deformation, by combining rigidity and compliance in a single material, have been widely sought. Bottom-up approaches, such as the self-organization of liquid crystals, offer potential advantages over top-down patterning methods such as photolithographic control of crosslink density, relating to the ease of preparation and fidelit...

The finite element method is applied to the biomechanics of brain tissue deformation. Emphasis is given to the deformations induced by the growth of tumors, and to the deformable registration of anatomical atlases with patient images. A uniform contraction of the tumor is first used to obtain an estimate of the shape of the brain prior to the growth of the tumor. A subsequent nonlinear regressi...

Finding a suitable estimation of stability domain around stable equilibrium points is an important issue in the study of nonlinear dynamical systems. This paper intends to apply a set of analytical-numerical methods to estimate the region of attraction for autonomous nonlinear systems. In mechanical and structural engineering, autonomous systems could be found in large deformation problems or c...

An extremum principle is presented covering problems in solid mechanics equilibrium analysis for piecewise linear softening materials. Problems formulated according to this principle are expressed in a mixed “stress and deformation” form. The mechanics interpretation is limited according to linear deformation kinematics. More specialized models, such as an exfremumprinciple in mixed form for li...

Experimental investigation of the solid state deformation properties of silicates at high temperatures has revealed that the deformation rate depends on the stress to a power of about 3 to 5 as well as strongly on the temperature. This highly nonlinear behavior leads to the potential of thermal runaway of the mantle’s cold upper boundary layer as it peels away from the surface and sinks through...

We studied the dynamic response of a foamlike forest of coiled carbon nanotubes under high strain rate deformation using a simple drop-ball test. The method is based on measuring the dynamic force between the ball and the foam on the substrate during the stages of penetration and restitution. The analysis of the forest’s morphology after impact has shown no trace of plastic deformation and a fu...