Wyszukiwarka
prof. dr hab. inż. Czesław Kazimierz Szymczak
Zatrudnienie
- profesor zwyczajny w Politechnika Gdańska
Publikacje
Filtry
wszystkich: 103
Katalog Publikacji
Rok 2012
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Biomechanics of the front abdominal wall as a potential factorleading to recurrence with laparoscopic ventral hernia repair
PublikacjaThis study investigated the front abdominal wallto describe its elasticity in vivo and searched for elongationsthat possibly stretched an implanted mesh, therebycausing fixation failure and subsequent recurrence.To measure front abdominal wall elongations, amodel of fascia movements was created. Eight healthyvolunteers were measured during exercise to determine theextent of elongations in their front abdominal wall. Videoswere...
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Elastic distortional buckling of thin-walled bars of closed quadratic cross-section
PublikacjaIn this study a thin-walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross-section distortion is investigated. The governing differential equation is derived with aid of the principle of stationary total potential energy. The critical load for the simply supported bar is found in analytical form and it is compared with the FEM solution. Sufficient accuracy...
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EXPERIMENTS AND SIMULATIONS FOR LAPAROSCOPICVENTRAL HERNIA REPAIR IMPROVEMENT
PublikacjaThe authors conducted a wide experimental and numerical study in order to determine effective approaches in the laparoscopic VH repair. At first the study covered identification of mechanical properties of the abdominal fascia, implants, tacks and transabdominalsutures. Basis on these data, the one and two-dimensional mathematical models were formulated and a number of numerical static and dynamic analyses were carried out. Then...
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Identification of the Vistula Mounting tower model using measured modal data
PublikacjaW pracy przedstawiono problem identyfikacji pięcioparametrowego modelu zabytkowej wieży twierdzy Wisłoujście. Poszukiwane parametry wyznaczono jako rozwiązanie problemu minimalizacji błędu średniokwadratowego pomierzonych dwóch pierwszych częstości i pierwszej postaci drgań własnych. Do tego celu wykorzystano hierarchiczną procedurę minimalizacji przy zastosowaniu analizy wrażliwości. Analiza numeryczna potwierdziła efektywność...
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Investigation of abdomen surface deformation due to life excitation: implications for implant selection and orientation in laparoscopic ventral hernia repair
PublikacjaVentral hernia is a common medical problem. Statistically there are around 10% recurrences of the sickness. The authors' former investigation proved edges of the hernia orifice displacements to be one of the factors causing recurrence. Thus, experimental investigation of the abdomen surface deformation due to some normal activities of people is studied.The extreme strains, their localization and directions are identified. The acquired...
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Modelling and Identification of Tower Type Historic Buildings
PublikacjaW pracy omawia się problemy modelowania i identyfikacji zabytkowych murowanych budowli wieżowych na przykładzie wieży Twierdzy Wisłoujście. Przedstawiono analizę modalną na podstawie dwukierunkowych pomiarów przyspieszeń na 9 poziomach wieży. Wyniki analizy posłużyły do identyfikacji modelu matematycznego budowli w postaci sztywnego bloku na podłożu sprężystym. Wykorzystano hierarchiczną procedurę opartą na analizie wrażliwości.
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Selected problems of stability of thin-walled columns with bisymmetric open cross-section
PublikacjaPraca dotyczy problemów stateczności osiowo ściskanych prętów o bisymetrycznym przekroju otwartym. Badano wpływ nieliniowości materiału pręta oraz wstępnego zakrzywienia osi na wyboczenie skrętne oraz początkową ścieżkę pokrytyczną. Na przykładach numerycznych wykazano, że w pewnych przypadkach stateczny, symetryczny punkt może zmienić się na symetryczny ale niestateczny, co oznacza możliwość redukcji siły krytycznej.
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Strain field of abdominal surface due to patients live excitations
PublikacjaPodano metodę opisu pola odkształceń powierzchni brzucha pacjenta podczas ruchów jego tułowia. Wyróżniono strefy brzucha o zróżnicowanej wielkości odkształceń ekstremalnych.
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Surgical implant used in ventral hernia repair subjected to physiological pressure - computer simulation
PublikacjaW streszczeniu przedstawiono matemayczny model implantu wszczepionego pacjentowi podczas laparoskopowej naprawy przepukliny brzusznej. Wykonano go z użyciem metody elementów skończonych. Przyjęto ortotropowy model materiałowy implantu.
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Thin-walled frames and grids - statics and dynamics
PublikacjaFrames and grids assembled with thin-walled beams of open cross-section are widely applied in various civil engineering and vehicle or machine structures. Static and dynamic analysis of theses structures may be carried out by means of different models, startingfrom the classical models made of beam elements undergoing the Kirchhoff assumptions to the FE discretization of whole frame into plane elements. The former model is very...
Rok 2013
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Effect of initial imperfection on buckling of thin-walled I columns
PublikacjaEffects of initial geometrical imperfections on critical buckling loads of thin-walled I columns are investigated. Torsional and flexural buckling are taken into account. The column behaviour is described in accord to the theory of thin-walled beams with nondeformable cross-section. Some numerical examples and conclusions related to effects of imperfections on properties of the critical loads are presented.
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Elastic distortional buckling of thin-walled bars of closed quadratic cross-section
PublikacjaIn this study a tin-walled bar with closed quadratic cross-section is considered. The elastic stability of axially compressed bar related to the cross-section distortion is investigated. The governing differential equatio is derived with aid of the principle of stationary potential energy. The critical load for simply supported bar is found in an analytical form and it is copared with the FEM solution. Sufficient accuracy of the...
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Physical and mathematical modelling of implant-fascia system in order to improve laparoscopic repair of ventral hernia
PublikacjaThis paper describes an investigation of biomechanical behaviour of hernia repair, which is focused on the selection of safe linking of certain type of implant with fascia in laparoscopic operation. The strength of various fixations of the implant to the fascia is analysed. Methods: The research is based on experimental observations of operated hernia model behaviour during a dynamic impulse load corresponding to post-operative...
Rok 2014
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Cough influence on fascia-mesh system built for a hernia repair - an experimental research
PublikacjaAn experimental approach to identify stronger and weaker fixation schemes in laparoscopic ventral hernia repair is presented in the paper. Two types of implants, whose mechanical properties are significantly different and five kinds of connectors are considered. Physical models of operated hernia have been built using those materials and porcine abdominal tissue. The models have been subjected to dynamic impulse load, similar to...
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Mechanical compatibility of implants used in hernia repair with abdominal wall
PublikacjaThe paper deals with a membrane model of a synthetic surgical mesh for treatment of abdominal hernia. The authors analyse the compatibility of two implant types with the human wall: Dualmesh Gore and Proceed. The finite element method is applied to simulate tjhe behavior of the proposed model. Due fact that recurrences are usually caused by connection failure, this study is focused on reaction forces in supports representing the...
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Numerical and experimental investigation of rotational stiffness of zed-purlins connection with sandwich panels
PublikacjaA rotational resistant stiffness of the zed-purlins connection with sandwich panels is investigated. A simple finite element method model of the connection is proposed. The numerical analysis of the model performed by ABAQUS software, in physically linear and geometrically nonlinear ranges, leads to the rotational resistant stiffness sought. The numerical solution obtained is verified experimentally. Two variants of distribution...
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SIMULATION OF PROCEED® SURGICAL MESH APPLIED TO VENTRAL HERNIA REPAIR
PublikacjaIn the present research, Proceed® implant is considered. The system is subjected to short-time dynamic pressure load, similar to post-operative cough naturally occurring in human abdomen. The model refers to a clinical case of 5cm of hernia operated by Proceed implant fixed by 15 joints every 3cm around the orifice. The simulations of the implanted mesh are performed by means of the Finite Element Method. The implant is modelled...
Rok 2016
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A PRELIMINARY STUDY ON THE OPTIMAL CHOICE OF AN IMPLANT AND ITS ORIENTATION IN VENTRAL HERNIA REPAIR
PublikacjaThis 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...
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Local buckling and initial post-buckling behaviour of channel member flange - analytical approach
PublikacjaThe local buckling and initial post-buckling behaviour of the cold-formed channel member flange is investigated. The governing nonlinear differential equation for axially compressed columns and beams undergoing pure bending is derived using the stationary total potential energy principle. The critical stress and initial post-buckling equilibrium path is determined by means of a perturbation approach. The results obtained allow...
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On local buckling of cold-formed channel members
PublikacjaThe paper deals with local buckling of the compressed flanges of cold-formed thin-walled channel beams subjected to pure bending or axially compressed columns. Arbitrarily shaped flanges of open cross-sections and the web-flange interactions are taken into account. Buckling deformation of a beam flange is described by displacement related to torsion of the flange about the line of its connection with the web. Total potential energy...
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