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The present work consists of proposing a new design of balloon-expandable aortic valve stent for use in patients with aortic valve stenosis. Finite element simulations were carried out to determine the Von Mises stresses and deformations and thereby select the design parameters of this device, which will allow its manufacturing and proper operation. The symmetrical condition of the stent facilitated the modeling process, as well as the determination of the smallest reduced diameter of the stent, a necessary condition for it to be moved safely within the artery. In this analysis, 316L stainless steel was used, an elastoplastic, isotropic and homogeneous behavior of the material was considered, also varying the thickness and radius of curvature at the ends of the stent sections. Loads were applied at the joints of these sections, obtaining equivalent stresses below the resistance limit of the material and above the elastic limit. The greatest reduction in stent diameter was obtained with a wire thickness of 0.5 mm and a radius of curvature of 0.5 mm. The mean diameter of the open device (22.987 mm) was reduced to 7.65 mm when applying a pressure of 43.8 MPa. [ABSTRACT FROM AUTHOR]

Nowadays, the high levels of copper production generates significant amounts of waste called tailings. In response to the latter, there is an increased need to understand the tailings behaviour in order to ensure the mechanical stability of dams. In this context, it is of great importance to study the resistance of tailings against the liquefaction phenomenon. Several studies have shown that the level of confining pressure affects the cyclic resistance of sands, proposing the correction factor Κσ. Similarly, it has been observed that the initial static shear stress also affects the cyclic strength, so the correction factor Κα has been introduced. However, the coupled effect of both variables, which corresponds to the real ground condition, has not been properly investigated for tailings sands. By means of undrained cyclic triaxial tests consolidated both isotropically and anisotropically, in this work the joint effect of both variables on the cyclic resistance of this material has been studied, for different levels of initial relative density. The results obtained from the coupled effect have been condensed through the parameter Κσα. [ABSTRACT FROM AUTHOR]

In a pavement structure, passing wheel loads impose cyclic stresses consisting of vertical, horizontal and shear components. Studies of the behavior of unbound granular materials (UGM, used for base and sub-base layers) under cyclic loading are mostly performed using the axisymmetric triaxial test with constant confining pressure (CCP test) and a cyclic variation of the axial stress. However, in this type of test only the vertical component of the cyclic stress path is considered. The oscillation of the horizontal stress can be reproduced by an additional cyclic variation of the confining pressure (VCP test). CCP and VCP tests are sometimes assumed to deliver similar residual and resilient deformations as long as the average stress is the same in both types of tests. However, this assumption is based on limited test data in the literature. The present paper documents a more detailed comparative study with CCP and VCP tests. The results show that only for some special stress paths both types of test deliver similar permanent axial or volumetric deformations. [ABSTRACT FROM AUTHOR]

In order to simulate the behavior of prefabricated ferrocement panels a homogenous model has been used. The behavior under in-plane lateral load has been evaluated. An experimental investigation was done to take into account the elastic and inelastic properties of the ferrocement considering it like a homogenous material. The numerical and experimental capacity curves are compared. The test results correspond well with the numerical model and show that the ferrocement is an excellent material to build dwelling housings. [ABSTRACT FROM AUTHOR]

This paper presents results of experimental tests of thin walled steel columns under pure axial loading. Twelve different elements in terms of slender factors were tested. Typical failure modes correspond to expected ones such as global or local buckling. Ultimate axial compression stresses were compared with analytical expressions given by the national building code, Norma Colombiana de Diseño y Construccion Sismo Resistente, NSR-98, presenting a relatively good agreement of results. Fabrication details as well as residual stresses play an important role when estimating axial strength of thin walled steel columns. [ABSTRACT FROM AUTHOR]