Wyniki wyszukiwania - BazTech

1

Regression Points in Non-Intrusive Polynomial Chaos Expansion Method and D-Optimal Design

Szepietowska K., Magnain B., Lubowiecka I., Florentin E.

Machine Dynamics Research

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2017

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Vol. 41, No. 2

5--16

EN

The paper addresses selected issues of uncertainty quantification in the modelling of a system containing surgical mesh used in ventral hernia repair. Uncertainties in the models occur due to variability of abdominal wall properties among others. In order to include them, a nonintrusive regression-based polynomial chaos expansion method is employed. Its accuracy depends on the choice of regression points. In the study, a relation between error of mean, standard deviation, 95th percentile and location of regression points is investigated in the models of implants with a single random variable. This approach is compared with a classic choice of points based on the D-optimality criterion.

2

A preliminary study on the optimal choice of an implant and its orientation in ventral hernia repair

Lubowiecka I., Szepietowska K., Szymczak C., Tomaszewska A.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 2

411--421

EN

This paper addresses the problem of ventral hernia repair. The main goals are to find an optimal surgical mesh for hernia repair and to define its optimal orientation in the abdominal wall to minimise the maximum force at the tissue-implant juncture. The optimal mesh is chosen from a set of orthotropic meshes with different stiffness ratios for typical hernia placement in the abdominal area. The implant is subjected to an anisotropic displacement field, different for the selected hernia placements. The assumed displacement fields correspond to regular human activity. Proper implantation of the mesh may determine the success of hernia repair and/or the postoperative comfort of patients. The proposed solution is based on FEM simulations of different surgical meshes behaviour. In typical hernia placements, the optimal orientation of the stiffer direction of the implant is perpendicular to the spine. However, the presented results show some cases that an oblique direction may be the optimum one.

3

Mechanical behaviour of the implant used in human hernia repair under physiological loads

Szepietowska K., Lubowiecka I.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 3

89--96

EN

In laparoscopic operations of abdominal hernias some recurrences still take place, even when applying a surgical mesh. This is usually caused by a failure of the connection between the tissue and the implant. The study deals with the influence of an implant’s orientation on forces in joints, which connect the mesh to human tissues. In the paper, the implant is modelled as a membrane structure within framework of the Finite Element Method. Two models are analysed: in the first one interaction between the mesh and a fascia is taken into account, in the second this interaction is not considered. Computations are conducted for two different material types of the implants: one with isotropic properties and second one with orthotropic properties. The models are validated by comparing dynamic numerical analysis with experimental outcomes, where load was simulating intraabdominal pressure during postoperative cough. Due to displacements of joints during activities like bending sideways or torsion of an abdomen, influence of kinematic extortions on forces in the joints is analysed. The outcome shows that position of the orthotropic implants is crucial and may strongly change the level of forces in the joints.

4

Komputerowa symulacja membrany stosowanej w leczeniu przepuklin brzusznych

Szepietowska K.

Aktualne Problemy Biomechaniki

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2011

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z. 5

159--164

PL

Z uwagi na częste nawroty choroby i chęć zminimalizowania bólu u pacjentów po operacjach przepukliny wykonanych metodą wideoskopową, lekarze poszukują optymalnej liczby zszywek łączących implant z tkanką ludzką. Celem pracy jest analiza wpływu warunków brzegowych na siłę ścinająca zszywki. Metodą Elementów Skończonych przeanalizowano dwa modele membran: z podporami sztywnymi i z podporami sprężystymi. Wywnioskowano, że przyjmowanie modelu z podporami sprężystymi jest bardziej wskazane, ponieważ model ten jest bezpieczniejszy i bardziej odpowiada rzeczywistości.

EN

Due to frequent recurrences and desire to minimize pain after hernia repair operation, physicians are looking for the optimal number of joints which connect implant with human tissue. The main aim of this study is to analyze the influence of boundary conditions on the shear strength in joints. Two models of membrane have been analyzed using Finite Element Method: with stiff supports and with elastic supports. In conclusion, the solution with elastic supports seems to be more appropriate due to the boundary conditions closer to real tissue-implant system and also safer if considering the shear force value in the joints.