Prof. Krzysztof Wiśniewski, PhD, DSc |
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Doctoral thesis
1985 | Analiza numeryczna statycznej stateczności powłoki cylindrycznej obciążonej wiatrem
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Habilitation thesis
1998 | Finite rotations of shells and beams. Extended equations and numerical models |
Professor
2011-07-15 | Title of professor |
Supervision of doctoral theses
1. | 2018-04-26 | Jarzębski Paweł | Zastosowanie algorytmów wielowątkowych i rozproszonych do zwiększenia efektywności Metody Elementów Skończonych | 1256 | ||
2. | 2008-10-30 | Panasz Przemysław | Nieliniowe modele powłok z 6 stopniami swobody bazujące na dwustopniowych aproksymacjach | 617 | ||
3. | 2008-06-26 | Sadłowski Piotr | Parametryzacje rotacji i algorytmy rozwiązywania równań dynamiki z rotacyjnymi stopniami swobody | 612 |
Recent publications
1. | Wiśniewski K., Turska E.♦, Reduced representations of assumed fields for Hu–Washizu solid-shell element, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-023-02275-1, Vol.71, pp.957-990, 2023 Abstract: Mixed eight-node (hexahedron) solid-shell elements based on the standard or partial version of the three-field Hu–Washizu (HW) functionals are developed for Green strain. Three reduced representations of the assumed stress/strain fields are selected. They improve effectiveness, yet retaining good accuracy and convergence properties. At the outset, the standard HW functional and the assumed stress/strain representations of the 3D solid element B8-15P (Weissman in Int J Numer Methods Eng 39:2337–2361, 1996) are used to derive a solid-shell element with 51 parameters. To eliminate locking, the ANS method is applied to the thickness strain (Betsch and Stein in Commun Numer Methods Eng 11:899–909, 1995) and to the transverse shear strain (Dvorkin and Bathe in Eng Comput 1:77–88, 1984). It is a correct element which, however, yields too large displacements for coarse meshes and trapezoidal through-thickness shapes. To improve the above formulation, the ζ-independent reduced representations of the assumed stress/ strain fields are selected and the transformations to Cartesian components are modified. The thickness strain is enhanced by the EAS method. The element with 35 parameters is derived from the standard/enhanced HW functional, but, to further reduce the assumed fields, partial/enhanced HW functionals are constructed from the 3D potential energy by applying the Lagrange multiplier method only to selected strain components. In the element with 27 parameters, this is applied to the constant in-plane strain and to the transverse shear strain while in the element with 19 parameters, to the constant in-plane strain only.Two other modifications are implemented to enhance the behavior of these elements: (A) the skew coordinates are used in the reduced representations of the in-plane stress/strain (Wisniewski and Turska in Int J Numer Methods Eng 90:506–536, 2012), and (B) the Residual Bending Flexibility correction of the transverse shear stiffness (MacNeal in Comput Struct 8(2):175–183, 1978) is adapted. Finally, the performance of the proposed solid-shell HW elements is demonstrated on several linear and non-linear examples for the linear elastic material and the hyper-elastic material. The proposed elements are compared to each other and to the best existing elements of this class. Keywords:Eight-node (hexahedron) solid-shell elements , Standard or partial Hu–Washizu functionals, Reduced representations of assumed stress/strain , RBF correction Affiliations:
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2. | Meissner M., Wiśniewski K., Investigation of damping effects on low-frequency steady-state acoustical behaviour of coupled spaces, Royal Society Open Science, ISSN: 2054-5703, DOI: 10.1098/rsos.200514, Vol.7, No.8, pp.200514-1-14, 2020 Abstract: In the low-frequency range, the acoustical behaviour of enclosed spaces is strongly influenced by excited acoustic modes resulting in a spatial irregularity of a steady-state sound field. In the paper, this problem has been examined theoretically and numerically for a system of coupled spaces with complex-valued conditions on boundary surfaces. Using a modal expansion method, an analytic formula for the Green's function was derived allowing to predict the interior sound field for a pure-tone excitation. To quantify the spatial irregularity of steady-state sound field, the parameter referred to as the mean spatial deviation was introduced. A numerical simulation was carried out for the system consisting of two coupled rectangular subspaces. Eigenfunctions and eigenfrequencies for this system were determined using the high-accuracy eigenvalue solver. As was evidenced by computational data, for small sound damping on absorptive walls the mean spatial deviation peaks at frequencies corresponding to eigenfrequencies of strongly localized modes. However, if the sound damping is much higher, the main cause of spatial irregularity of the interior sound field is the appearance of sharp valleys in a spatial distribution of a sound pressure level. Keywords:interior acoustics, coupled spaces, steady-state sound field, modal expansion method, sound damping, Green's function Affiliations:
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3. | Meissner M., Wiśniewski K., Influence of room modes on low-frequency transients: theoretical modeling and numerical predictions, JOURNAL OF SOUND AND VIBRATION, ISSN: 0022-460X, DOI: 10.1016/j.jsv.2019.02.012, Vol.448, pp.19-33, 2019 Abstract: In the low-frequency range, a sound reproduction in enclosures is strongly influenced by excited room modes. While the spectral impact of acoustic modes on a room response is well recognized, there is no sufficient knowledge on how these modes affects transients. In the paper this issue has been examined theoretically and numerically for a room excited by a tone burst by using a modal expansion method supported by a computer implementation. To quantify a temporal accuracy of a sound reproduction, the new metrics referred to as the tone burst reproduction error was introduced. The basis for determining this quantity was a deviation between the tone burst amplitude and the amplitude of a sound pressure computed via the Hilbert transform. A numerical simulation was performed for an irregularly shaped enclosure having a form of two-room coupled system. Calculation results have proved that a high inaccuracy of a tone burst reproduction occurs at receiving points corresponding to sharp dips in a distribution of the steady-state sound pressure level. This is because in these points an amplitude of transient sound is much bigger than a tone burst amplitude. It was discovered that strong narrow peaks in the tone burst reproduction error are located at centers of vortices in the active sound intensity vector field. An influence of a sound damping in a room on a reproduction of a tone burst was also examined and it was found that a substantial increase in a wall sound absorption does not significantly improves a tone burst reproduction because it does not eliminate sharp dips in a distribution of the steady-state sound pressure level. Keywords:room acoustics, room modes, transients, tone burst, discrete Hilbert transform, sound intensity vector field Affiliations:
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4. | Nowak Z., Nowak M., Pęcherski R.B., Wiśniewski K., Widłaszewski J., Kurp P.♦, Computational modeling of thermoplastic behavior of inconel 718 in application to laser-assisted bending of thin-walled tubes, INTERNATIONAL JOURNAL FOR MULTISCALE COMPUTATIONAL ENGINEERING, ISSN: 1543-1649, DOI: 10.1615/IntJMultCompEng.2019029858, Vol.17, No.3, pp.317-338, 2019 Abstract: Laser-assisted tube bending is a promising manufacturing process which enables production of forms and shapes that cannot be obtained by purely mechanical bending. It is particularly suitable for high hardness and brittle materials, such as nickel alloys, ceramics and cast iron. In the current paper, mechanical loading and simultaneous heating by a moving laser beam are used in a controlled manner to obtain the required deformation. Experimental investigation of the Inconel 718 (IN718) alloy provides the basis for identification of parameters of two constitutive models, which encompass softening phenomena and the coupling of temperature and strains. Numerical simulations are conducted to provide more insight into the laser-assisted bending process of the IN718 thin-walled tubes. Temperature, stress and deformation fields are determined in sequentially coupled thermomechanical analyses using the FE code ABAQUS. Laser beam is modeled as a surface heat flux using the dedicated DFLUX procedure. The temperature field is used as a thermal load in the static general step, together with an external mechanical load. The process of tube bending is controlled by the displacement of the piston rod of the actuator, while the thrust force is the resulting value. Keywords:laser-assisted bending of tubes, identification of material parameters, numerical simulations Affiliations:
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5. | Wiśniewski K., Turska E.♦, Improved nine-node shell element MITC9i with reduced distortion sensitivity, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-017-1510-4, Vol.62, No.3, pp.499-523, 2018 Abstract: The 9-node quadrilateral shell element MITC9i is developed for the Reissner-Mindlin shell inematics, the extended potential energy and Green strain. The following features of its formulation ensure an improved behavior: 1. The MITC technique is used to avoid locking, and we propose improved ransformations for bending and transverse shear strains, which render that all patch tests are passed for the regular mesh, i.e. with straight element sides and middle positions of midside nodes and a central node. 2. To reduce shape distortion effects, the so-called corrected shape functions of Celia and Gray (Int J Numer Meth Eng 20:1447–1459, 1984) are extended to shells and used instead of the standard ones. In effect, all patch tests are passed additionally for shifts of the midside nodes along straight element sides and for arbitrary shifts of the central node. 3. Several extensions of the corrected shape functions are proposed to enable computations of non-flat shells. In particular, a criterion is put forward to determine the shift parameters associated with the central node for non-flat elements. Additionally, the method is presented to construct a parabolic side for a shifted midside node, which improves accuracy for symmetric curved edges. Drilling rotations are included by using the drilling Rotation Constraint equation, in a way consistent with the additive/multiplicative rotation update scheme for large rotations. We show that the corrected shape functions reduce the sensitivity of the solution to the regularization parameter γ of the penalty method for this constraint. The MITC9i shell element is subjected to a range of linear and non-linear tests to show passing the patch tests, the absence of locking, very good accuracy and insensitivity to node shifts. It favorably compares to several other tested 9-node elements. Keywords:9-node shell element MITC9i, Two-level approximation of strains, Patch tests, Corrected shape functions, Node shift parameters, Coarse mesh accuracy, Drilling rotations Affiliations:
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6. | Jarzębski P., Wiśniewski K., Evaluation of Partial Factorization for Reduction of Finite Element Matrices, ENGINEERING TRANSACTIONS (ROZPRAWY INŻYNIERSKIE), ISSN: 0867-888X, Vol.65, No.1, pp.163-170, 2017 Abstract: In this paper, we present the concept of Partial Factorization [1] and discuss its possible applications to the Finite Element method. We consider: (1) reduction of the element tangent matrix, which is particularly important for mixed/enhanced elements and (2) reduction of the sub-domain matrices of the Domain Decomposition (DD) equation solvers run either sequen-tially on a single machine or in parallel on a cluster of computers. We demonstrate that Partial Factorization can be beneficial for these applications. Keywords:multi-scale models of multi-layer shells, mixed/enhanced finite elements, parallel computing, domain decomposition, solvers Affiliations:
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7. | Jarzębski P., Wiśniewski K., Taylor R.L.♦, On parallelization of the loop over elements in FEAP, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-015-1156-z, Vol.56, pp.77-86, 2015 Abstract: In this paper, we consider parallelization of the loop over elements using OpenMP in FEAP (Taylor, 2014), which is a research FE code, very popular at universities. Even for a serial version of FEAP (a cluster version also exists) such a parallelization is a non-trivial task due to the existing architecture of this code, which complicates efficient parallelization. First, we compare the serial version of FEAP to the parallel code Warp3D (Dodds et al., 2014), considering the usage of time and memory. As we found, Warp3D is much faster but uses more memory than FEAP. An analysis of Warp3D helps us to devise our method of parallelization of the loop over elements. Next, we describe several changes in FEAP, which were necessary to parallelize the loop over elements using OpenMP. In particular, the subroutine assembling elemental matrices is identified as crucial to good performance, and several directives for the mutual exclusion synchronization of OpenMP are implemented and tested. Finally, we demonstrate the performance of the parallelized FEAP, designated as ompFEAP, on numerical examples involving 3D and shell elements of FEAP as well as user’s elements. We conclude that ompFEAP, using the directive ATOMIC for synchronization of the assembling, provides a very good speedup and efficiency. Keywords:Parallelization, OpenMP, Finite element method, FEAP, 3D and shell elements Affiliations:
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8. | Wiśniewski K., Panasz P., Two improvements in formulation of nine-node element MITC9, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.4399, Vol.93, pp.612-634, 2013 Abstract: The paper concerns a well-known two-dimensional nine-node quadrilateral element MITC9, which is based on two-level approximations of strains (assumed strain method). The element has good accuracy, but does not pass the patch test. nine-node element, two-level approximation of strains, assumed strain method, two-dimensional MITC9, patch test, sensitivity to shape distortions, coarse mesh accuracy Affiliations:
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9. | Panasz P., Wiśniewski K., Turska E.♦, Reduction of mesh distortion effects for nine-node elements using corrected shape functions, FINITE ELEMENTS IN ANALYSIS AND DESIGN, ISSN: 0168-874X, DOI: 10.1016/j.finel.2012.11.003, Vol.66, pp.83-95, 2013 Abstract: The paper concerns two-dimensional nine-node quadrilateral elements based on the Green strain and the two-level approximations of strains. These approximations reduce locking well for regular meshes but cannot prevent the drop of accuracy when the side and central nodes are shifted from the middle positions. Two-dimensional nine-node elements, Corrected shape functions, Two-level approximations of strains, Patch tests, Shape distortions Affiliations:
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10. | Wiśniewski K., Turska E.♦, Four-node mixed Hu-Washizu shell element with drilling rotation, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.3335, Vol.90, pp.506-536, 2012 Abstract: In this paper, enhanced four-node shell elements with six DOFs/node based on the Hu–Washizu (HW) functional are developed for Green strain. The drilling rotation is included through the drilling rotation constraint equation. The key features of the approach are as follows. four-node mixed shell element with six DOFs/node, pure or partial Hu–Washizu functionals, drilling rotation, optimal representations, skew coordinates Affiliations:
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11. | Wiśniewski K., Wagner W.♦, Turska E.♦, Gruttmann F.♦, Four-node Hu-Washizu elements based on skew coordinates and contravariant assumed strain, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2010.07.008, Vol.88, pp.1278-1284, 2010 Abstract: Mixed 4-node elements based on the Hu–Washizu (HW) functional are developed for the representation of the assumed strain in the natural basis at the element’s center, i.e. for the contravariant transformation rule. In other aspects, the formulation is identical as in our previous paper [9], to which this note is an addendum. Four-node finite elements, Hu–Washizu functional, Plane stress, Mixed elements, Skew coordinates, Contravariant assumed strain Affiliations:
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12. | Wiśniewski K., Turska E.♦, Improved four-node Hu-Washizu elements based on skew coordinates, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2009.01.011, Vol.87, pp.407-424, 2009 Abstract: Mixed 4-node elements based on the Hu–Washizu (HW) functional are developed for stress and strain representations in various coordinates, including the skew, natural and Cartesian ones. The HW functional is used in incremental form, suitable for non-linear materials. The key features of our approach are as follows. 4-Node finite elements, Plane stress, Incremental Hu–Washizu functional, Mixed elements, Mixed/enhanced elements, Skew coordinates Affiliations:
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13. | Wiśniewski K., Turska E.♦, Improved four-node Hellinger-Reissner elements based on skew coordinates, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.2343, Vol.76, pp.798-836, 2008 Abstract: Mixed four-node elements based on the Hellinger–Reissner (HR) functional are developed for stress representations in various coordinates, including the skew, natural and Cartesian ones. The two-field HR functional is used in the classical form and in the incremental form suitable for non-linear materials. four-node finite elements, incremental Hellinger–Reissner functional, assumed stress element, assumed stress/enhanced strain element, skew coordinates Affiliations:
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14. | Panasz P., Wiśniewski K., Nine-node shell elements with 6 dofs/node based on two-level approximations, FINITE ELEMENTS IN ANALYSIS AND DESIGN, ISSN: 0168-874X, DOI: 10.1016/j.finel.2008.05.002, Vol.44, pp.784-796, 2008 Abstract: The paper concerns 9-node quadrilateral shell elements derived for Reissner's kinematics. They are based on the Green strain and potential energy, and are applicable to large (unrestricted) rotations. The characteristic features of the developed elements are as follows: Nine-node shell elements, 6 dofs/node, Drilling rotation, Two-level approximation, Assumed strain, Selective reduced integration Affiliations:
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15. | Wiśniewski K., Kowalczyk P., Turska E., Analytical DSA for explicit dynamics of elastic-plastic shells, COMPUTATIONAL MECHANICS, ISSN: 0178-7675, DOI: 10.1007/s00466-006-0068-3, Vol.39, No.6, pp.761-785, 2007 Abstract: The paper presents an analytical constitutive design sensitivity analysis (DSA) algorithm for explicit dynamics of elastic-plastic finite rotation shells. Two explicit dynamical algorithms for finite rotation shells are presented, and the DSA is developed for the one formulated in terms of the rotation vector and its time derivatives, {ψ,ψ˙,ψ¨}. The hypo-elastic constitutive model based on the Green-McInnis-Naghdi stress rate is used to derive an incremental algorithm in terms of ‘back-rotated’ objects. The associative deviatoric Huber-Mises plasticity modified by plane stress conditions is implemented in the form suitable for finite rotation/small elastic strain increments. The analytical DSA is developed for the above-specified problem, with the design derivatives calculated w.r.t. material parameters. Design-differentiation of the dynamic algorithm and the scheme of handling the history data and the predicted values in differentiation, which is crucial in computing correct derivatives, are described. Besides, we show how to avoid Newton loops in the DSA algorithm, when such a loop is present in the constitutive algorithm. Numerical examples show that, despite a great complexity of the solution algorithm for the finite-rotation elastic-plastic shells, it is feasible to compute analytical design derivatives of very good accuracy. Keywords:Explicit dynamics, Finite rotation shell, Elastic-plastic material, Analytical Design Sensitivity Analysis for constitutive parameters Affiliations:
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16. | Wiśniewski K., Turska E., Enhanced Allman quadrilateral for finite drilling rotations, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, ISSN: 0045-7825, DOI: 10.1016/j.cma.2005.11.003, Vol.195, pp.6086-6109, 2006 Abstract: The paper concerns a four-node quadrilateral element based on Allman shape functions undergoing finite (unrestricted) drilling rotations, and aims at improving its accuracy and facilitating its implementation. New Allman shape functions for finite drilling rotations, Enhanced Assumed Displacement Gradient method for formulations with rotations, Enhanced Allman finite elements Affiliations:
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17. | Wiśniewski K., Kowalczyk P., Turska E., On the computation of design derivatives for Huber–Mises plasticity with non‐linear hardening, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.678, Vol.57, No.2, pp.271-300, 2003 Abstract: This paper concerns design sensitivity analysis (DSA) for an elasto–plastic material, with material parameters depending on, or serving as, design variables. The considered constitutive model is Huber–Mises deviatoric plasticity with non‐linear isotropic/kinematic hardening, one which is applicable to metals. design sensitivity analysis, elasto–plastic material with non‐linear hardening, parallel finite element code Affiliations:
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18. | Wiśniewski K., Finite Rotations of Shells and Beams Extended Equations and Numerical Models (Praca habilitacyjna), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.9, pp.1-178, 1997 | |||||||||||||||||||
19. | Wiśniewski K., Analiza numeryczna statycznej stateczności powłoki cylindrycznej obciążonej wiatrem (Praca doktorska), Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.50, pp.1-144, 1985 |
List of recent monographs
1. 1 | Wiśniewski K., Finite rotation shells: Basic equations and finite elements for Reissner kinematics, Lecture Notes on Numerical Methods in Engineering and Sciences, Springer Verlag, pp.1-498, 2010 |
List of chapters in recent monographs
1. 653 | Meissner M., Wiśniewski K., Sound Informs, Harms, Heals 2019, rozdział: Analytical and Numerical Study of Spatial Irregularity of Sound Field in Coupled Rooms, Wydawnictwa AGH, pp.82-97, 2021 | |
2. 637 | Wiśniewski K., Turska E.♦, Analysis of Shells, Plates, and Beams: A State of the Art Report, rozdział: On Transverse Shear Strains Treatment in Nine-Node Shell Element MITC9i, Springer, pp.421-440, 2020 | |
3. 613 | Wiśniewski K., Turska E.♦, Recent Developments in the Theory of Shells, rozdział: On Performance of Nine-Node Quadrilateral Shell Elements 9-EAS11 and MITC9i, Springer, pp.711-725, 2019 | |
4. 507 | Wiśniewski K., Turska E.♦, Shell-like Structures. Advanced Theories and Applications, rozdział: Selected topics on mixed/enhanced four-node shell elements with drilling rotation, Springer International Publishing, 572, pp.247-288, 2017 | |
5. 51 | Wiśniewski K., Turska E.♦, Shell-like Structures. Non-classical Theories and Applications, rozdział: Recent Improvements in Hu-Washizu Shell Elements with Drilling Rotations, Springer, pp.391-412, 2011 |
Conference papers
1. | Jarzębski P., Wiśniewski K., Performance of the parallel FEAP in calculations of effective material properties using RVE, CMM, 3rd Polish Congress of Mechanics and 21st International Conference on Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.241-244, 2016 Abstract: The paper concerns parallelization of an FE code for machines with shared memory in order to speed up computations of large models. parallelization, OpenMP, finite element method, FEAP, RVE, shells Affiliations:
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Conference abstracts
1. | Wiśniewski K., Turska E.♦, Recent improvements to nine-node shell element MITC9 with drilling rotations, SSTA 2017, Shell Structures: Theory and Applications, 2017-10-11/10-13, Gdańsk (PL), Vol.4, pp.399-402, 2018 Abstract: The paper describes our improved 9-node quadrilateral shell element MITC9i, which is derived for the Reissner-Mindlin shell kinematics, the extended potential energy functional and Green strain. 1. The MITCi technique is used to avoid locking and it is based on the improved transformations proposed in (Wisniewski & Panasz 2013) for a membrane element. Here, these transformations are extended to bending/twisting and transverse shear shell strains. 2. To reduce the shape distortion effects, the so-called corrected shape functions (CSF) of (Celia & Gray 1984) are used instead of the isoparametric ones, and we propose the method of computation the shift parameters for non-flat shell elements. 3. The drilling rotations are included via the drilling Rotation Constraint and the penalty method. This rotation is used in the multiplicative/additive update scheme valid for large (unrestricted) rotations. The effect of the MITC9i technique and the CSF is that all three patch tests are passed, also for shifted side nodes along the straight edges and for arbitrary shifts of an interior node. The MITC9i shell element was subjected to a range of linear and non-linear numerical tests described in (Wisniewski & Turska 2017); here we provide additional examples illustrating its accurate and robust behavior. Keywords:9-node shell element MITC9,two-level approximation of strains, corrected shape functions, node shift parameters, drilling rotations Affiliations:
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2. | Nowak Z., Nowak M., Pęcherski R.B., Wiśniewski K., Widłaszewski J., Kurp P.♦, Computational Modelling of Thermoplastic Behaviour of Inconel 718 in Application to Laser-Assisted Bending of Thin-Walled Alloy Tubes, WCCM2018, 13th World Congress on Computational Mechanics, 2018-07-22/07-27, Nowy Jork (US), pp.1, 2018 | ||||||||||
3. | Wiśniewski K., Turska E.♦, Recent results on nine-node shell elements using two-level approximation of strain, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P122, pp.1-2, 2016 Keywords: finite element method, shell elements Affiliations:
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4. | Jarzębski P., Wiśniewski K., Evaluation of partial factorization for condensation of shell and solid-shell elemental matrices, SolMech 2016, 40th Solid Mechanics Conference, 2016-08-29/09-02, Warszawa (PL), No.P100, pp.1-2, 2016 Keywords: finite element methods, solid-shell elements Affiliations:
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5. | Jarzębski P., Wiśniewski K., On calculation of effective material properties using RVE method by parallelized FE code for shell applications, PCM-CMM 2015, 3rd Polish Congress of Mechanics and 21st Computer Methods in Mechanics, 2015-09-08/09-11, Gdańsk (PL), pp.375-376, 2015 Abstract: This paper concerns parallelization of an FE code for machines with shared memory in order to speed up computations of large models. We parallelized the loop over elements in the research code FEAP using OpenMP, which required several modifications of the code and a specific method of synchronization for assembling, for details see [2]. The parallel solver was also applied. We demonstrate performance of the parallelized FEAP, designated as ’ompFEAP’, in calculations of effective properties of materials using the RVE method. Two RVE examples are computed, for a heterogenous metal-ceramic composite and for a ceramic foam with a complicated micro-structure. We conclude that ompFEAP provides a very good speedup and efficiency causing only a small increase in memory usage. Keywords:parallelization, OpenMP, finite element method, FEAP, RVE, shells Affiliations:
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6. | Jarzębski P., Wiśniewski K., Corrected shape functions for six-node triangular element for heat conduction, CMM 2013, 20th International Conference on Computer Methods in Mechanics, 2013-08-27/08-31, Poznań (PL), pp.345-353, 2014 Abstract: In this paper, we derived the corrected shape functions for 6-node triangular element using the concept proposed in (Celia & Gray 1984). These shape functions were implemented in the two-dimensional 6-node triangular element for heat conduction as a replacement of the isoparametric ones. The numerical tests indicate that, for distorted meshes, the new element is more accurate than the standard element. Comparisons of the accuracy of a range of triangular and quadrilateral elements also are provided. Keywords:Six-node triangular element, heat conduction, corrected shape functions, sensitivity to mesh distortion, patch test Affiliations:
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7. | Jarzębski P., Wiśniewski K., On parallelization of the loop over elements for composite shell computations, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.227-228, 2014 | ||||||||||
8. | Wiśniewski K., Turska E.♦, Recent improvements in mixed/enhanced shell elements with drilling rotation, SolMech 2014, 39th Solid Mechanics Conference, 2014-09-01/09-05, Zakopane (PL), pp.27-28, 2014 | ||||||||||
9. | Wiśniewski K., Turska E.♦, On mixed/enhanced Hu-Washizu shell elements with drilling rotation, SSTA, 10th Jubilee Conference on Shell Structures - Theory and Applications, 2013-10-16/10-18, Gdańsk (PL), DOI: 10.1201/b15684-117, Vol.3, pp.469-472, 2014 Abstract: Mixed/enhanced four-node shell elements with six dofs/node based on the Hu-Washizu (HW) functional are developed for Green strain. The shell HW functional is derived from the shell potential energy functional instead of from the three-dimensional HW functional. Partial HW functionals, differing in the bending/twisting part and the transverse shear part, are obtained. For the membrane part of HW shell elements, a 7-parameter stress, a 9-parameter strain and a 2-parameter EADG enhancement are selected as performing best. The assumed representations of stress and strain are defined in skew coordinates in the natural basis at the element's center. The drilling rotation is included through the drilling Rotation Constraint (RC) equation and the Perturbed Lagrange method. The spurious mode is stabilized using the gamma method. Several versions of shell HW elements are tested using several benchmark examples and the optimally performing element is selected (HW29) in (Wisniewski & Turska 2012). Affiliations:
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10. | Jarzębski P., Wiśniewski K., On corrected shape functions for six-node triangular elements applied to heat conduction problems, CMM 2013, 20th International Conference on Computer Methods in Mechanics, 2013-08-27/08-31, Poznań (PL), No.MS09, pp.11-12, 2013 | ||||||||||
11. | Wiśniewski K., Turska E.♦, On Shell Elements Derived from Hu-Washizu Functional, SolMech 2012, 38th Solid Mechanics Conference, 2012-08-27/08-31, Warszawa (PL), pp.228-229, 2012 | ||||||||||
12. | Panasz P., Wiśniewski K., Modeling of intersections using the nine-node assumed strain shell element, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.162-1-2, 2011 | ||||||||||
13. | Panasz P., Wiśniewski K., On computation of sensitivities of multi-layer shells using elements with additional parameters, CMM 2011, 19th International Conference on Computer Methods in Mechanics, 2011-05-09/05-12, Warszawa (PL), pp.275-1-2, 2011 | ||||||||||
14. | Panasz P., Wiśniewski K., On behavior of nonlinear nine-node shell elements in thin limit, SolMech 2010, 37th Solid Mechanics Conference, 2010-09-06/09-10, Warszawa (PL), pp.320-321, 2010 | ||||||||||
15. | Wiśniewski K., Kowalczyk P., Turska E., DSA for Elastic-plastic Shells and Explicit Dynamics, 8th U.S. National Congress on Computational Mechanics, 2005-07-24/07-28, Austin, Texas (US), No.1681, pp.1, 2005 Keywords: design sensitivity analysis, finite element method, shell structures, elasto-plasticity Affiliations:
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16. | Wiśniewski K., Kowalczyk P., Turska E., DSA for elastic-plastic finite rotation shells under dynamic loads, ICTAM XXI, 21st International Congress of Theoretical and Applied Mechanics, 2004-08-15/08-21, Warszawa (PL), No.12679, pp.361, 2004 Keywords: Design sensitivity analysis, finite element method, finite rotations, shell elements Affiliations:
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17. | Wiśniewski K., Kowalczyk P., Turska E., DSA for elastic-plastic finite rotation shells under dynamic loads, ICTAM04, 21st International Congress of Theoretical and Applied Mechanics, 2004-08-15/08-21, Warszawa (PL), No.12679, pp.1-2, 2004 Abstract: The paper describes a constitutive algorithm for elastic-plastic finite rotation shells and explicit dynamics with design derivatives calculated w.r.t. We show that despite a great complexity of the solution algorithm for the finite-rotation elastic-plastic shells, it is feasible to compute analytical design derivative of this algorithm, and the yielded sensitivities are of very good accuracy. Keywords:design sensitivity analysis, finite elment method, shell structures, dynamics, finite rotations Affiliations:
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