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Auricchio F.,University of Pavia | Auricchio F.,Center for Advanced Numerical Simulations | Conti M.,University of Pavia | Marconi S.,University of Pavia | And 3 more authors.
Computers in Biology and Medicine | Year: 2013

Traditional surgical repair of ascending aortic pseudoaneurysm is complex, technically challenging, and associated with significant mortality. Although new minimally invasive procedures are rapidly arising thanks to the innovations in catheter-based technologies, the endovascular repair of the ascending aorta is still limited because of the related anatomical challenges. In this context, the integration of the clinical considerations with dedicated bioengineering analysis, combining the vascular features and the prosthesis design, might be helpful to plan the procedure and predict its outcome. Moving from such considerations, in the present study we describe the use of a custom-made stent-graft to perform a fully endovascular repair of an asymptomatic ascending aortic pseudoaneurysm in a patient, who was a poor candidate for open surgery. We also discuss the possible contribution of a dedicated medical images analysis and patient-specific simulation as support to procedure planning. In particular, we have compared the simulation prediction based on pre-operative images with post-operative outcomes. The agreement between the computer-based analysis and reality encourages the use of the proposed approach for a careful planning of the treatment strategy and for an appropriate patient selection, aimed at achieving successful outcomes for endovascular treatment of ascending aortic pseudoaneurysms as well as other aortic diseases. © 2013 Elsevier Ltd.

Auricchio F.,University of Pavia | Auricchio F.,Center for Advanced Numerical Simulations | Auricchio F.,CNR Institute of Neuroscience | Beirao da Veiga L.,University of Milan | And 6 more authors.
Computer Methods in Applied Mechanics and Engineering | Year: 2013

In this work we present the application of isogeometric collocation techniques to the solution of spatial Timoshenko rods. The strong form equations of the problem are presented in both displacement-based and mixed formulations and are discretized via NURBS-based isogeometric collocation. Several numerical experiments are reported to test the accuracy and efficiency of the considered methods, as well as their applicability to problems of practical interest. In particular, it is shown that mixed collocation schemes are locking-free independently of the choice of the polynomial degrees for the unknown fields. Such an important property is also analytically proven. © 2013 Elsevier B.V..

Auricchio F.,University of Pavia | Auricchio F.,Center for Advanced Numerical Simulations | Da Veiga L.B.,University of Milan | Lovadina C.,Center for Advanced Numerical Simulations | And 5 more authors.
Computational Mechanics | Year: 2013

Several finite element methods for large deformation elastic problems in the nearly incompressible and purely incompressible regimes are considered. In particular, the method ability to accurately capture critical loads for the possible occurrence of bifurcation and limit points, is investigated. By means of a couple of 2D model problems involving a very simple neo-Hookean constitutive law, it is shown that within the framework of displacement/pressure mixed elements, even schemes that are inf-sup stable for linear elasticity may exhibit problems when used in the finite deformation regime. The roots of such troubles are identi-fied, but a general strategy to cure them is still missing. Furthermore, a comparison with displacement-based elements, especially of high order, is presented. © Springer-Verlag Berlin Heidelberg 2013.

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