We study the linear instability with respect to necking of a filament of polymeric fluid undergoing uniaxial extension. Contrary to the widely discussed Considère criterion, we find the onset of instability to relate closely to the onset of downward curvature in the time (and so strain) evolution of the zz component of the molecular strain, for extension along the z axis. In establishing this r...

A bespoke test rig has been designed to facilitate testing of magneto-rheological (MR) elastomers (MREs) under equi-biaxial tension using a standard universal test machine. Tests were performed up to 10% strain on both isotropic and anisotropic MREs with and without the application of an external magnetic field. Assumptions regarding the material’s response were used to analyse stress–strain re...

Mechanical properties of self-scrolling binormal nanohelices with a rectangular cross-section are investigated under uniaxial tensile and compressive loads using nanorobotic manipulation and Cosserat curve theory. Stretching experiments demonstrate that small-pitch nanohelices have an exceptionally large linear elasticity region and excellent mechanical stability, which are attributed to their ...

A numerical method for simulating the extensional dynamics of elongating ®laments of non-Newtonian ̄uids in a ®lament stretching rheometer is presented. The boundary element method, in conjunction with either the Oldroyd-B or the generalized multimode Upper-Convected Maxwell constitutive model, is used to calculate the transient evolution of the liquid interface, the applied force on the station...

PURPOSE To determine biomechanical properties of the superior labrum-biceps tendon complex submitted to continuous and sudden mechanical strain. METHODS Eighteen shoulder specimens from 15 unclaimed corpses, ages ranging from 20 to 40 years, were submitted to continuous or sudden tensile tests using 3 different traction machines. Shoulders presenting signs of degenerative diseases or preexist...

[Purpose] The aim of this study was to examine whether plantar flexor static stretching and dynamic stretching using an Aero-Step results in changes in foot pressure during gait in healthy adults. [Subjects] Eighteen normal adults were randomly allocated to either a dynamic stretching using an Aero-Step group (DSUAS) group (n = 8) or a static stretching (SS) group (n = 10). [Methods] The DSUAS ...

The cytoskeleton is an important factor in the functional and structural adaption of cells to mechanical forces. In this study we investigated the impact of microtubules and the acto-myosin machinery on the kinetics of force-induced reorientation of NIH3T3 fibroblasts. These cells were subjected to uniaxial stretching forces that are known to induce cellular reorientation perpendicular to the s...

We study the mechanical property of a two-dimensional filament with constant spontaneous curvature and under uniaxial applied force. We derive the equation that governs the stable shape of the filament and obtain analytical solutions for the equation. We find that for a long filament with positive initial azimuth angle (the azimuth angle is the angle between x axis and the tangent of the filame...

Tagged MRI and finite-element (FE) analysis are valuable tools in analyzing cardiac mechanics. To determine systolic material parameters in three-dimensional stress-strain relationships, we used tagged MRI to validate FE models of left ventricular (LV) aneurysm. Five sheep underwent anteroapical myocardial infarction (25% of LV mass) and 22 wk later underwent tagged MRI. Asymmetric FE models of...

We investigate the mechanical response of thin sheets perforated with a square array of mutually orthogonal cuts, which leaves a network of squares connected by small ligaments. Our combined analytical, experimental and numerical results indicate that under uniaxial tension the ligaments buckle out of plane, inducing the formation of 3D patterns whose morphology is controlled by the load direct...