NASA/TM—2013-217850 1 ∆t∗ nondimensional time step, ∆t/(L/V0) kinetic energy dissipation rate 1 kinetic energy dissipation rate computed from deviatoric strain rate 3 kinetic energy dissipation rate computed from pressure dilatation κ angular wave number μ kinematic viscosity ν spectroscopic wave number ωi vorticity vector Ω volume ρ density σ filter damping coefficient τij stress tensor ζ enst...

Fatigue crack growth rate depends not only on the load amplitude, but also on the morphology of crack path. The strain energy density theory has the ability to analyze crack growth rate. A strain energy density crack growth model is proposed. It can predict the lifetime of fatigue crack growth for mixed mode cracks while an equation for mode I crack is also obtained. The validity of the model i...

We consider stochastic processes, St ≡ (St x : x ∈ Z d) ∈ S d 0 with S0 finite, in which spin flips (i.e., changes of St x) do not raise the energy. We extend earlier results of Nanda-Newman-Stein that each site x has almost surely only finitely many flips that strictly lower the energy and thus that in models without zero-energy flips there is convergence to an absorbing state. In particular, ...

Athermal steady-state plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated include the distributions of energy drops, stress drops, and strain intervals between the flow events. We show that simulations at a single density in conjunction with an equilibrium-liq...

The direct calculation of the elastic and piezoelectric tensors of solids can be accomplished by treating homogeneous strain within the framework of density-functional perturbation theory. By formulating the energy functional in reduced coordinates, we show that the strain perturbation enters only through metric tensors, and can be treated in a manner exactly paralleling the treatment of other ...

We show how strain stiffening affects the elastic response to internal forces, caused either by material defects and inhomogeneities or by active forces that molecular motors generate in living cells. For a spherical force dipole in a material with a strongly nonlinear strain energy density, strains change sign with distance, indicating that, even around a contractile inclusion or molecular mot...

The passive mechanical properties of blood vessel mainly stem from the interaction of collagen and elastin fibers, but vessel constriction is attributed to smooth muscle cell (SMC) contraction. Although the passive properties of coronary arteries have been well characterized, the active biaxial stress-strain relationship is not known. Here, we carry out biaxial (inflation and axial extension) m...

The formulation for thermal stress and electric displacement in an in®nite thermopiezoelectric plate with an interface and multiple cracks is presented. Using Green's function approach and the principle of superposition, a system of singular integral equations for the unknown temperature discontinuity de®ned on each crack face is developed and solved numerically. The formulation can then be use...

background different clinical and epidemiological studies using dual-energy x-ray absorptiometry have shown an increased prevalence of low bone mineral density in patients with inflammatory bowel diseases.the aim of this study was to assess the correlation between bone density and the disease activity in patients with ulcerative colitis. methods in this cross-sectional study, 52 patients with u...