1,721,103 research outputs found
Indagine FEM probabilistica sull'affidabilità della tecnica elastografica per il riconoscimento di tumori
No full text
Sensitivity of angioplasty effects to vessel material properties by probabilistic analysis
No full textThe great interest in Finite Element simulations of cardiovascular operations, such
as stenting, angioplasty, aneurysm intervention, for improving the reliability of endovascular
devices, is confirmed by the considerable number of papers published in this field. This paper
presents the results of a numerical investigation aimed at identifying the most important
parameters, among the tissue mechanical properties, that co-operate to the success of the
angioplasty operation. In fact in angioplasty simulations mechanical properties of both artery
and plaque tissues are fundamental for the success of the intervention, while they affect in a
minor way the stenting operation. By means of the Finite Element program ANSYS, several 2D
models, representing the longitudinal and the transversal cross section of the vessel with an
atherosclerotic plaque, have been developed. The plaque has been considered an isotropic
elasto-plastic material, with a bilinear or a Drucker Prager model; for the artery, an elastic
isotropic or orthotropic material, with data taken from the literature, has been employed. In
order to apply a more realistic loading condition, the angioplasty balloon has been modelled
also; displacement has been assigned to the balloon and the behaviour of plaque and artery
during its expansion and deflation has been analysed. The effect of a different interaction
between the artery and the plaque, bonded always or sliding with friction, has been considered
also. Employing the toolbox of probabilistic design of ANSYS, a probabilistic analysis has
been carried out in order to assess the sensitivity of output parameters, such as maximum
stress and lumen gain, with respect to input parameters, such as plaque material properties.
Results show that in case of axisymmetric stenosis the plaque material properties are most
significant, in particular the Young modulus and the yield stress, while in case of spur plaque
the artery behaviour, linear or non-linear elastic, plays a more important role
Review of Experimental Investigations on Compressibility of Arteries and Introduction of a New Apparatus
No full textArterial tissue incompressibility is a common notion used in numerical simulations and analytical studies. However, only a few experimental investigations have been performed to characterize arterial tissue incompressibility. Such studies have used various approaches, ranging from the initial purely mechanical measurements in 1954 to the more recent image-based analyses (2004). The results of these studies are rather diverse because different arteries have been tested (human/dog/mouse, carotid/pulmonary/iliac). This has therefore made accurate comparisons between studies challenging. In the first part of this report, a review of the experimental investigations on the compressibility of arteries is presented, with particular focus on the test rigs that have been used. In the second part of this report, a novel simple apparatus to test samples under physiological or supra-physiological conditions is described. Recommendations for a testing procedure are also provided. Finally, preliminary results on porcine renal arteries indicate significant levels of compressibility are possible (>10 %), thereby suggesting the need for further investigation
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