Czesław Szymczak | Gdansk University of Technology (original) (raw)

Papers by Czesław Szymczak

Advanced Structured Materials, 2019

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Shell Structures: Theory and Applications Volume 4, 2017

The study presents a methodology of defining a numerical model of human abdominal wall based on t... more The study presents a methodology of defining a numerical model of human abdominal wall based on the experimentally registered data of the abdomen geometry due to variations of the intraabdominal pressure. The abdominal wall is modelled here as a simple homogeneous membrane structure made of linear orthotropic material The displacements registered during the increase of pressure are compared with the re-sults of the model static simulations.

Advances in Intelligent Systems and Computing, 2018

In this paper a research towards understanding of mechanics of ventral hernia operated with the u... more In this paper a research towards understanding of mechanics of ventral hernia operated with the use of Physiomesh Open image in new window implant and SecureStrap Open image in new window staples is described. Experimental and numerical studies are conducted for that purpose. Experimental works cover uni-axial tension tests of the implant samples and of the implant-staples-tissue system. Also experiments on implant-staples-tissue models, representing operated hernia, subjected to impulse pressure loading are performed. Based on that, constitutive model of the mesh has been identified and failure load of the staples has been determined. In the experiments on the operated hernia systems subjected to pressure loading safe loading level has been determined and failure modes connected to higher pressure values have been observed. Finally, in the numerical simulations of the operated hernia model, built according to FEM rules, it has been proved that failures observed experimentally result from exceeding of the load bearing capacity of the staples considered in this study.

Vibrations in Physical Systems, 2012

W pracy omawia sie problemy modelowania i identyfikacji zabytkowych murowanych budowli wiezowych ... more W pracy omawia sie problemy modelowania i identyfikacji zabytkowych murowanych budowli wiezowych na przykladzie wiezy Twierdzy Wisloujście. Przedstawiono analize modalną na podstawie dwukierunkowych pomiarow przyspieszen na 9 poziomach wiezy. Wyniki analizy posluzyly do identyfikacji modelu matematycznego budowli w postaci sztywnego bloku na podlozu sprezystym. Wykorzystano hierarchiczną procedure opartą na analizie wrazliwości.

Journal of the Mechanical Behavior of Biomedical Materials, 2021

The study concerns mechanical behaviour of a living human abdominal wall. A better mechanical und... more The study concerns mechanical behaviour of a living human abdominal wall. A better mechanical understanding of a human abdominal wall and recognition of its material properties is required to find mechanically compatible surgical meshes to significantly improve the treatment of ventral hernias. A non-invasive methodology, based on in vivo optical measurements is proposed to determine strains of abdominal wall corresponding to a known intraabdominal pressure. The measurement is performed in the course of a standard procedure of peritoneal dialysis. A dedicated experimental stand is designed for the experiment. The photogrammetric technique is employed to recover the three-dimensional surface geometry of the anterior abdominal wall at the initial and terminal instants of the dialysis. This corresponds to two deformation states, before and after filling the abdominal cavity with dialysis fluid. The study provides information on strain fields of living human abdominal wall. The inquiry is aimed at principal strains and their directions, observed at

Journal of Theoretical and Applied Mechanics, 2016

This paper addresses the problem of ventral hernia repair. The main goals are to find an optimal ... more 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.

Advanced structured materials, 2023

The paper deals with local buckling of a compressed single flange of thin-walled channel cold- fo... more The paper deals with local buckling of a compressed single flange of thin-walled channel cold- formed columns and beams made of aluminum alloy. Material is described by means of the Ramberg-Osgood constitutive equation. Axial compression of the columns and beams undergoing bending is taken into consid- eration. A simple model of the member flange in the form a long beam elastically connected to the web is used to find the critical buckling stress. The governing differential equation is derived with the aid of the sta- tionary total potential energy principle. The tangent modulus theory is applied to find the critical buckling stress and buckling modes. Analytical formulas of the critical stress and buckling mode are positively verified by the FEM and FSM analysis of numerical examples.

Advanced Structured Materials, 2019

The article reviews a number of papers in the light of buckling analysis of thin-walled columns a... more The article reviews a number of papers in the light of buckling analysis of thin-walled columns and beams. Stability of thin-walled columns and beams are considered a vital engineering science issue in both historical and present-day approaches. The paper refers to the recent authors’ works of the 2012–2019 period, published in leading journals. Similar review of stability problems of thin-walled structures developed at Gdansk University of Technology is published in Szymczak (A review of stability problems of thin-walled structures developed at Gdansk University of Technology, 69–78, 2003, [58]), Szymczak (Selected problems of stability of thin-walled columns with bisymmetric cross-section, 111–128, 2012, [59]). This paper is a continuation of the earlier reviews. Only selected references are given.

Continuum Mechanics and Thermodynamics, 2018

The investigation concerns local buckling of compressed flanges of axially compressed composite c... more The investigation concerns local buckling of compressed flanges of axially compressed composite channel columns. Cooperation of the member flange and web is taken into account here. The buckling mode of the member flange is defined by rotation angle a flange about the line of its connection with the web. The channel column under investigation is made of unidirectional fibre-reinforced laminate. Two approaches to member orthotropic material modelling are performed: the homogenization with the aid of theory of mixture and periodicity cell or homogenization upon the Voigt-Reuss hypothesis. The fundamental differential equation of local buckling is derived with the aid of the stationary total potential energy principle. The critical buckling stress corresponding to a number of buckling half-waves is assumed to be a minimum eigenvalue of the equation. Some numerical examples dealing with columns are given here. The analytical results are compared with the finite element stability analysis carried out by means of ABAQUS software. The paper is focused on a close analytical solution of the critical buckling stress and the associated buckling mode while the web-flange cooperation is assumed.

Effects of initial geometrical imperfections on critical buckling loads of thin-walled I columns ... more Effects 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.

Przedstwiono uwagi do artkulu Tews R., Rachowicz W. ''Numerical Analysis of Thin-Walled F... more Przedstwiono uwagi do artkulu Tews R., Rachowicz W. ''Numerical Analysis of Thin-Walled Frames with Flexible Joints'', Archives of Civil Engineering, 51, 3, 2005, ss. 344-369.

Lecture Notes in Computational Vision and Biomechanics, 2020

The paper presents a numerical approach to describe mechanical behavior of anisotropic textile ma... more The paper presents a numerical approach to describe mechanical behavior of anisotropic textile material, which is a selected abdominal prosthesis. Two constitutive nonlinear concepts are compared. In the first one the material is considered composed from two families of threads (dense net model) and in the second one the material is homogeneous but anisotropic (as proposed by Gassel, Ogden, Holzapfel). Parameters of both models are identified based on experimental tensile tests (uni-axial and bi-axial, simple and cyclic). The constitutive relations are applied in numerical membrane model of the prosthesis applied in the abdominal wall. Its mechanical responses to the pressure loading has been compared, also to deflection experimentally observed in physical model of the operated hernia of the same geometry. The authors find that both constitutive models properly describe the implant’s mechanics, but further studies are needed to possibly approach the outcome of hyperelastic anisotropic model to experimental results obtained for synthetic knit mesh.

International Journal of Architectural Heritage, 2020

The paper presents a survey of the historic Arch-cathedral bell tower in Vilnius induced by the a... more The paper presents a survey of the historic Arch-cathedral bell tower in Vilnius induced by the appearance of cracks in the structure after a new bell system installation. An attempt is undertaken ...

A concept of a beam superelement is suggested as a new tool in the static analysis of structures ... more A concept of a beam superelement is suggested as a new tool in the static analysis of structures made of thin-walled members. This proposal seems to be especially attractive for treating the problems where the existing one-dimensional models do not provide proper solutions. This class of problems includes for instance the torsion of thin-walled beams with battens and the determination of the bimoment distribution at the nodes of frames made of thin-walled members. The entire segment of the thin-walled beam with warping stiffener or the whole node of the frame is modelled with shell elements. The stiffness matrix of such thin-walled beam superelement can be estimated according to the standard procedure of the enforced unit displacements. The accuracy of the proposed onedimensional model has proved to be comparable to that offered by the detailed FEM model where the whole structure is represented by a very large number of shell elements.

Acta Mechanica

Distortional buckling of axially compressed columns of box-like composite cross sections with and... more Distortional buckling of axially compressed columns of box-like composite cross sections with and without internal diaphragms is investigated in the framework of one-dimensional theory. The channel members are composed of unidirectional fibre-reinforced laminate. Two approaches to the member orthotropic material are applied: homogenization based on the theory of mixture and periodicity cells, and homogenization based on the Voigt-Reuss hypothesis. The principle of stationary total potential energy is applied to derive the governing differential equation. The obtained buckling stress is valid in the linear elastic range of column material behaviour. Numerical examples address simply supported columns, and analytical critical stress formulas are derived. The analytical and FEM solutions are compared, and sufficient accuracy of the results is observed.

Thin-Walled Structures, 1991

Advanced Structured Materials, 2019

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Shell Structures: Theory and Applications Volume 4, 2017

The study presents a methodology of defining a numerical model of human abdominal wall based on t... more The study presents a methodology of defining a numerical model of human abdominal wall based on the experimentally registered data of the abdomen geometry due to variations of the intraabdominal pressure. The abdominal wall is modelled here as a simple homogeneous membrane structure made of linear orthotropic material The displacements registered during the increase of pressure are compared with the re-sults of the model static simulations.

Advances in Intelligent Systems and Computing, 2018

In this paper a research towards understanding of mechanics of ventral hernia operated with the u... more In this paper a research towards understanding of mechanics of ventral hernia operated with the use of Physiomesh Open image in new window implant and SecureStrap Open image in new window staples is described. Experimental and numerical studies are conducted for that purpose. Experimental works cover uni-axial tension tests of the implant samples and of the implant-staples-tissue system. Also experiments on implant-staples-tissue models, representing operated hernia, subjected to impulse pressure loading are performed. Based on that, constitutive model of the mesh has been identified and failure load of the staples has been determined. In the experiments on the operated hernia systems subjected to pressure loading safe loading level has been determined and failure modes connected to higher pressure values have been observed. Finally, in the numerical simulations of the operated hernia model, built according to FEM rules, it has been proved that failures observed experimentally result from exceeding of the load bearing capacity of the staples considered in this study.

Vibrations in Physical Systems, 2012

W pracy omawia sie problemy modelowania i identyfikacji zabytkowych murowanych budowli wiezowych ... more W pracy omawia sie problemy modelowania i identyfikacji zabytkowych murowanych budowli wiezowych na przykladzie wiezy Twierdzy Wisloujście. Przedstawiono analize modalną na podstawie dwukierunkowych pomiarow przyspieszen na 9 poziomach wiezy. Wyniki analizy posluzyly do identyfikacji modelu matematycznego budowli w postaci sztywnego bloku na podlozu sprezystym. Wykorzystano hierarchiczną procedure opartą na analizie wrazliwości.

Journal of the Mechanical Behavior of Biomedical Materials, 2021

The study concerns mechanical behaviour of a living human abdominal wall. A better mechanical und... more The study concerns mechanical behaviour of a living human abdominal wall. A better mechanical understanding of a human abdominal wall and recognition of its material properties is required to find mechanically compatible surgical meshes to significantly improve the treatment of ventral hernias. A non-invasive methodology, based on in vivo optical measurements is proposed to determine strains of abdominal wall corresponding to a known intraabdominal pressure. The measurement is performed in the course of a standard procedure of peritoneal dialysis. A dedicated experimental stand is designed for the experiment. The photogrammetric technique is employed to recover the three-dimensional surface geometry of the anterior abdominal wall at the initial and terminal instants of the dialysis. This corresponds to two deformation states, before and after filling the abdominal cavity with dialysis fluid. The study provides information on strain fields of living human abdominal wall. The inquiry is aimed at principal strains and their directions, observed at

Journal of Theoretical and Applied Mechanics, 2016

This paper addresses the problem of ventral hernia repair. The main goals are to find an optimal ... more 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.

Advanced structured materials, 2023

The paper deals with local buckling of a compressed single flange of thin-walled channel cold- fo... more The paper deals with local buckling of a compressed single flange of thin-walled channel cold- formed columns and beams made of aluminum alloy. Material is described by means of the Ramberg-Osgood constitutive equation. Axial compression of the columns and beams undergoing bending is taken into consid- eration. A simple model of the member flange in the form a long beam elastically connected to the web is used to find the critical buckling stress. The governing differential equation is derived with the aid of the sta- tionary total potential energy principle. The tangent modulus theory is applied to find the critical buckling stress and buckling modes. Analytical formulas of the critical stress and buckling mode are positively verified by the FEM and FSM analysis of numerical examples.

Advanced Structured Materials, 2019

The article reviews a number of papers in the light of buckling analysis of thin-walled columns a... more The article reviews a number of papers in the light of buckling analysis of thin-walled columns and beams. Stability of thin-walled columns and beams are considered a vital engineering science issue in both historical and present-day approaches. The paper refers to the recent authors’ works of the 2012–2019 period, published in leading journals. Similar review of stability problems of thin-walled structures developed at Gdansk University of Technology is published in Szymczak (A review of stability problems of thin-walled structures developed at Gdansk University of Technology, 69–78, 2003, [58]), Szymczak (Selected problems of stability of thin-walled columns with bisymmetric cross-section, 111–128, 2012, [59]). This paper is a continuation of the earlier reviews. Only selected references are given.

Continuum Mechanics and Thermodynamics, 2018

The investigation concerns local buckling of compressed flanges of axially compressed composite c... more The investigation concerns local buckling of compressed flanges of axially compressed composite channel columns. Cooperation of the member flange and web is taken into account here. The buckling mode of the member flange is defined by rotation angle a flange about the line of its connection with the web. The channel column under investigation is made of unidirectional fibre-reinforced laminate. Two approaches to member orthotropic material modelling are performed: the homogenization with the aid of theory of mixture and periodicity cell or homogenization upon the Voigt-Reuss hypothesis. The fundamental differential equation of local buckling is derived with the aid of the stationary total potential energy principle. The critical buckling stress corresponding to a number of buckling half-waves is assumed to be a minimum eigenvalue of the equation. Some numerical examples dealing with columns are given here. The analytical results are compared with the finite element stability analysis carried out by means of ABAQUS software. The paper is focused on a close analytical solution of the critical buckling stress and the associated buckling mode while the web-flange cooperation is assumed.

Effects of initial geometrical imperfections on critical buckling loads of thin-walled I columns ... more Effects 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.

Przedstwiono uwagi do artkulu Tews R., Rachowicz W. ''Numerical Analysis of Thin-Walled F... more Przedstwiono uwagi do artkulu Tews R., Rachowicz W. ''Numerical Analysis of Thin-Walled Frames with Flexible Joints'', Archives of Civil Engineering, 51, 3, 2005, ss. 344-369.

Lecture Notes in Computational Vision and Biomechanics, 2020

The paper presents a numerical approach to describe mechanical behavior of anisotropic textile ma... more The paper presents a numerical approach to describe mechanical behavior of anisotropic textile material, which is a selected abdominal prosthesis. Two constitutive nonlinear concepts are compared. In the first one the material is considered composed from two families of threads (dense net model) and in the second one the material is homogeneous but anisotropic (as proposed by Gassel, Ogden, Holzapfel). Parameters of both models are identified based on experimental tensile tests (uni-axial and bi-axial, simple and cyclic). The constitutive relations are applied in numerical membrane model of the prosthesis applied in the abdominal wall. Its mechanical responses to the pressure loading has been compared, also to deflection experimentally observed in physical model of the operated hernia of the same geometry. The authors find that both constitutive models properly describe the implant’s mechanics, but further studies are needed to possibly approach the outcome of hyperelastic anisotropic model to experimental results obtained for synthetic knit mesh.

International Journal of Architectural Heritage, 2020

The paper presents a survey of the historic Arch-cathedral bell tower in Vilnius induced by the a... more The paper presents a survey of the historic Arch-cathedral bell tower in Vilnius induced by the appearance of cracks in the structure after a new bell system installation. An attempt is undertaken ...

A concept of a beam superelement is suggested as a new tool in the static analysis of structures ... more A concept of a beam superelement is suggested as a new tool in the static analysis of structures made of thin-walled members. This proposal seems to be especially attractive for treating the problems where the existing one-dimensional models do not provide proper solutions. This class of problems includes for instance the torsion of thin-walled beams with battens and the determination of the bimoment distribution at the nodes of frames made of thin-walled members. The entire segment of the thin-walled beam with warping stiffener or the whole node of the frame is modelled with shell elements. The stiffness matrix of such thin-walled beam superelement can be estimated according to the standard procedure of the enforced unit displacements. The accuracy of the proposed onedimensional model has proved to be comparable to that offered by the detailed FEM model where the whole structure is represented by a very large number of shell elements.

Acta Mechanica

Distortional buckling of axially compressed columns of box-like composite cross sections with and... more Distortional buckling of axially compressed columns of box-like composite cross sections with and without internal diaphragms is investigated in the framework of one-dimensional theory. The channel members are composed of unidirectional fibre-reinforced laminate. Two approaches to the member orthotropic material are applied: homogenization based on the theory of mixture and periodicity cells, and homogenization based on the Voigt-Reuss hypothesis. The principle of stationary total potential energy is applied to derive the governing differential equation. The obtained buckling stress is valid in the linear elastic range of column material behaviour. Numerical examples address simply supported columns, and analytical critical stress formulas are derived. The analytical and FEM solutions are compared, and sufficient accuracy of the results is observed.

Thin-Walled Structures, 1991

Using of warping stiffeners is a popular remedy for the small torsional stiffness of thin-walled ... more Using of warping stiffeners is a popular remedy for the small torsional stiffness of thin-walled beams. The torsional performance of thin-walled beams can be substantially improved by adding lateral diaphragms, battens or cross lattices. The warping stiffeners can be included in a standard model of a thin-walled beam with the non-deformable cross-section as a warping spring supports. However, the formulas available in the literature do not provide the proper estimation of that additional nodal stiffness. Looking for a more exact model of warping stiffeners the authors of the present study applied the concept of a beam superelement. The entire segment of the thin-walled beam with warping stiffener has been modelled with QUAD4 shell elements of the FEM system MSC NASTRAN. The stiffness matrix of that thin-walled beam superelement has been estimated according to the standard procedure of the unit enforced displacements. The problem of determination of the effective length of the superelement is discussed in the paper. Some numerical examples are presented for the thin-walled beams with battens.