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A mechanical model of heart valves with chordae for in silico real-time computations and cardiac surgery planning

Gaidulis G., Kačianauskas R., Kizilova N., Romashov Y.

Engineering Transactions

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2018

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Vol. 66, iss. 4

391--412

EN

In this paper, a two-dimensional (2D) model of the dynamics of mitral valve with chordae is developed based on in vivo data of the periodical motion of the valve leaflets digitized from the ultrasound imaging. The chordae are considered as viscoelastic springs described by the five-element rheological model. The model allows fast numerical computations of forces in the chordae and leaflets at different locations of the chordae of a different order. It can be used in real-time computations of the patient-specific geometry for optimal surgery planning when the mitral valve insufficiency is associated with broken chordae, and neochordae implantation is needed.

2

Numerical elastoplastic analysis of trabeculae in lumbar vertebral body

Maknickas A., Alekna V., Ardatov O., Kizilova N., Tamulaitiene M., Kacianauskas R.

Engineering Transactions

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2017

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Vol. 65, iss. 1

83--88

EN

This paper presents a numerical modelling of lumbar vertebrae L1 by employing the finite element method. The three-dimensional model of vertebral body is derived by processing CT data and DICOM format files. The model includes cortical shell, trabecular bone and posterior elements. The formation of trabecular structure was performed by script-controlled ellipsoidal cut-outs. In order to define the nonlinear relationship between the stress and the strain, the Ramberg-Osgood equation was applied. Therefore, the von Mises stress was assumed to characterise the stressed state of bone tissue due to 1 and 7 MPa compression load. According to specific difficulties for “in vitro” and “in vivo” investigation methods, this “in silico” technique may provide new insight for further understanding of the trabecular bone behaviour in terms of plastic deformation.

3

Biomechanical analysis of asymmetric mesio-distal molar positions loaded by a symmetric cervical headgear

Kizilova N., Geramy A., Romashov Y.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 4

97--106

EN

Purpose: The plane 2d model and 3d finite element model of the headgear attached to two molars with different mesio-distal location are studied to show the asymmetric mechanical effects produced by symmetrically loaded headgear. In daily dental practice the asymmetrical location of molars is usually ignored. Methods: Six 3D finite element models of a symmetric cervical headgear were designed in SolidWorks 2011. The models showed symmetric molar position (model 1), 0.5 to 2 mm of anterior-posterior molar difference (models 2-5) and a significant asymmetry with 10 mm of difference in the locations (model 6). The head gear was loaded with 3N of force applied at the cervical headgear. The forces and moments produced on terminal molars are assessed. Results: It is shown the difference between the forces acting at the longer and shorter outer arms of the headgear increases with increase in the distance. The significant numeric difference in the forces has been found: from 0.0082 N (model 1) to 0.0324 N (model 5) and 0.146 N (model 6). These small forces may produce unplanned distal tipping and rotation of the molars around their vertical axes. The most important funding was found as a clockwise yaw moment in the system when is viewed superio-inferiorly. The yaw moment has been computed between -0.646 N•mm (model 1) and -1.945 N•mm (model 5). Conclusions: Therefore even small asymmetry in location of molars loaded by a symmetric cervical headgear will produce undesirable move-ment and rotation of the teeth that must be taken into account before applying the treatment.

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Mathematical models of biofluid flows in compliant ducts

Kizilova N., Hamadiche M., Gad-el-Hak M.

Archives of Mechanics

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2012

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Vol. 64, nr 1

65-65

EN

A literature review of liquid and gas flows in compliant tubes, ducts and cavities in living bodies is presented. The common features of such flows as determined by fluid–structure interactions and system instabilities are described. The corresponding mathematical models are given and theoretical and numerical results are discussed. Original new results on flow stabilization in layered viscoelastic tubes in biosystems are also presented.