An approach to consider the arterial residual stresses in modelling of a patient-specific arteryJanez Urevc
, Miroslav Halilovič
, Milan Brumen
, Boris Štok
, 2016, original scientific article
Abstract: In this work, the residual stress state of a human common carotid artery is predicted using the so-called thermomecha- nical analogy approach. The purpose of the approach is to enable consistent mapping of residual stresses and the respec- tive configuration from a circular arterial segment to a patient-specific arterial geometry. This is achieved by applying proper volumetric dilatations to the actual arterial stress-free in vivo geometry, which makes use of the analogy that states that the bending stresses can be obtained on an equivalent manner by applying proper thermal dilatations. The common carotid artery data are obtained in vivo from a healthy 28-year-old man using non-invasive methods. The pre- dicted residual stresses of the common carotid artery are in good quantitative agreement with the data from prior work in this field. The approach is validated by predicting the common carotid artery zero-stress state configuration, where a sector-like (cut-open) state is obtained. With this approach, it is thus possible to predict the residual stresses as well as the configuration of patient-specific arterial geometry without the need to model its cut-open zero-stress configuration.
Keywords: patient-specific artery, common carotid artery, residual stresses, arterial zero-stress state, thermomechanics, finite element method
Published: 12.07.2017; Views: 681; Downloads: 285
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The vibrations of microbeams and nanotubesJurij Avsec
, 2011, original scientific article
Abstract: Temperature variations can significantly change the dynamic characteristics of macro-, micro- and nano-structures. In the presented article we have studied the microbeams and nanotubes under thermal effects. Microbeams and nanotubes will be very important in the future in the fields of MEMS and NEMS. For the physical explanation of vibrations of nanotubes classical mechanics is valid with some limitations. We have taken into account the influence of thermal force, axial force in rotating shaft and also gyroscopic effect. The effect of temperature-dependent material properties was considered primarily with respect to the temperature variations. On the basis of our analytical model it is possible to determine the vibrational characteristics in a very wide range of temperatures. In the presented paper it is shown for the first time in scientific literature the combined influence of temperature, gyroscopic effects and rotor speeds on shaft and beam vibrations.
Keywords: vibrations of microbeams, vibrations of nanotubes, rotor vibration, thermomechanics, nanomechanics
Published: 05.06.2012; Views: 1531; Downloads: 28
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Vibration of beams and rotating shafts under thermal effectsJurij Avsec
, 2009, original scientific article
Abstract: Temperature variations can significantly change the dynamic characteristics of structures. In the presented paper we have studied the clamped isotropic rotor under thermal effects. We have studied aluminium and copper beam. Because the expansion is restrained by the clamping, the beam undergoes internal stresses, which induce changes in dynamic characteristics. We have also expanded and developed Marques and Inman model as well as Bahzad and Bastami model. We have taken into account the compound influence of thermal force, axial force in rotating shaft and gyroscopic effect. The behavior of rotating shaft is studied in the temperature range of 250-700 K. The influence of temperature-dependent material properties was considered primarily with respect to temperature variations. The presented research work demonstrates a very good agreement between experimental data and results from our vibrational model. On the basis of the proposed analytical model it is possible to determine the vibrational characteristics in very wide range of temperatures. The reported paper is the first one in scientific literature to consider collectively the combined influence of temperature, gyroscopic effects and rotor speeds on shaft and beam vibrations.
Keywords: beam vibrations, rotor vibrations, temperature effects, mechanics, thermomechanics
Published: 05.06.2012; Views: 2380; Downloads: 55
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Thermal vibrational analysis for simply supported beam and clamped beamJurij Avsec
, Maks Oblak
, 2007, original scientific article
Abstract: The presented paper shows how the temperature field in beams has impact on vibrations of beams. Due to the relatively high possible temperature variations in beams we have developed the mathematical model where fundamental thermomechanical properties of state are functions of temperature such as modulus of elasticity, Poisson number, linear expansion coefficient, shear modulus and some other important thermodynamic properties of state. The detailed analysis shows, that also small changes of temperature cause significant changes of natural frequencies for beams. The comparison between our analytical model and experimental data shows good agreement. In the presented paper it is possible to find for the first time in scientific literature the application of the combination of statistical thermodynamics and the theory of vibration at the same time.
Keywords: statistical thermomechanics, vibrations, vibrational theory, temperature effects, simply supported beams, clamped beams, thermomechanical properties
Published: 31.05.2012; Views: 1101; Downloads: 73
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