In this paper, an elastic shell model is presented for postbuckling prediction of a long thinwalledcylindrical shell under axial compression. The Ritz method is applied to solve the governingequilibrium equation of a cylindrical shell model based on the von-Karman type nonlinear differentialequations. The postbuckling equilibrium path is obtained using the energy method for a long thin-walledcy...

OBJECTIVE To evaluate left ventricular (LV) function and carotid intima-media thickness (IMT) in patients with axial SpA in relationship to underlying disease severity. METHODS We recruited 104 patients with axial SpA and 50 controls. Detailed transthoracic echocardiography was performed and analysed with two-dimensional speckle tracking strain analysis for systolic function and tissue Dopple...

Recently, the feasibility of visualizing the characteristics of bonding at an inclusion-background boundary using axial-shear strain elastography was demonstrated. In this paper, we report a feasibility study on the utility of the axial-shear strain elastograms in the classification of in vivo breast tumor as being benign or malignant. The study was performed using data sets obtained from 15 be...

It has previously been observed experimentally and simulated numerically that when a thin film bonded to a much softer substrate is subjected to a uni-axial compression parallel to the interface, the initial buckled pattern will suffer a secondary bifurcation that doubles the period of the original pattern when the compressive strain reaches a critical value. This perioddoubling phenomenon is a...

Determining the depth dependence of the shear properties of articular cartilage is essential for understanding the structure-function relation in this tissue. Here, we measured spatial variations in the shear modulus G of bovine articular cartilage using a novel technique that combines shear testing, confocal imaging and force measurement. We found that G varied by up to two orders of magnitude...

[1] Differential stresses in a cylindrical rock of polycrystalline Mg2SiO4 ringwoodite were measured at room temperature with pressures up to 10 GPa, axial strains in excess of 20%, and strain rates between 5 10 5 and 4 10 6 s , using the deformation-DIA coupled with monochromatic X-rays. The sample exhibited ductile behavior in axial shortening-lengthening cycles with reproducible hysteresis l...

Axial speed of sound (SOS) measurements have been successfully applied to noninvasively evaluate tendon load, while preliminary studies showed that this technique also has a potential clinical interest in the follow up of tendon injuries. The ultrasound propagation theory predicts that the SOS is determined by the effective stiffness, mass density and Poisson’s ratio of the propagating medium. ...

The Cramér-Rao Lower Bounds (CRLB) are derived for the displacement and strain estimation in directions orthogonal to the ultrasonic beam axis, using a previously-described recorrelation method of axial, lateral and elevational motion estimation. We also compare it to the lateral tracking method that involves the sole use of the axial signal in the transverse direction. Our theoretical results,...

In this paper we prove the global solvability of a class of fourth-order nonlinear boundary value problems that govern the deformation of a Hollomon’s power-law plastic beam subject to an axial compression and nonlinear lateral constrains. For certain ranges of the acting axial compression force, the solvability of the equations follows from the monotonicity of the fourth order nonlinear differ...

The quality of strain estimates in elastography is typically quantified by several quality factors such as the elastographic signal-to-noise ratio, the elastographic contrast-to-noise ratio and the spatial axial and lateral resolutions. While theoretical and simulation works have led to established upper bounds of these image quality factors in axial strain elastography, the performance limitat...