Maciej Lewandowski, M.Sc., Eng.

Department of Mechanics of Materials (ZMM)
Division of Micromechanics of Materials (PMM)
position: doctoral student
telephone: (+48) 22 826 12 81 ext.: 453
room: 140
e-mail: maclewan

Recent publications
1.Lewandowski M.J., Gajewski M., Gizejowski M., Numerical analysis of influence of intermediate stiffeners setting on the stability behaviour of thin-walled steel tank shell, Thin-Walled Structures, ISSN: 0263-8231, DOI: 10.1016/j.tws.2015.01.019, Vol.90, pp.119-127, 2015
Abstract:

Cylindrical bolted steel tanks with H/D~1 can be made from very thin steel courses the thickness of which is determined by tension. The important issue is to stiffen the whole shell with intermediate stiffeners to prevent from stability loss in situations when the tank is empty and exposed to a strong wind. The FEM package Abaqus with nonlinear Riks algorithm was used for analysis. A parametric study programmed in python, internal Abaqus language was conducted to establish the influence of number and position of intermediate stiffeners on buckling resistance of the tank. After calculating nearly one thousands tasks, results were gathered with python script and compared with classic design recommendations proposed in Eurocode 3, DIN 18 800 Part 4 and AWWA D103-09. Simplified analytical approaches present in current standards are rather conservative and one may want to look for more sophisticated methods of analysis of tank shells presented in this paper for more economical design of such structures. From the comparison of the results obtained with different numerical strategies such as linear buckling analysis (LBA), geometrically nonlinear analysis of perfect (GNA) and imperfect (GNIA) structure a necessity of taking into account imperfections in GNA arises. Otherwise a capacity of the shell structure may be overestimated even over the value obtained from LBA.

Keywords:

Thin-walled steel tanks, Optimal stiffening ring location, Buckling, Finite element method, Python programming, Geometrical imperfections

Affiliations:
Lewandowski M.J.-IPPT PAN
Gajewski M.-other affiliation
Gizejowski M.-other affiliation
2.Stupkiewicz S., Lewandowski M.J., Lengiewicz J., Micromechanical analysis of friction anisotropy in rough elastic contacts, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2014.07.013, Vol.51, No.23-24, pp.3931-3943, 2014
Abstract:

Computational contact homogenization approach is applied to study friction anisotropy resulting from asperity interaction in elastic contacts. Contact of rough surfaces with anisotropic roughness is considered with asperity contact at the micro scale being governed by the isotropic Coulomb friction model. Application of a micro-to-macro scale transition scheme yields a macroscopic friction model with orientation- and pressure-dependent macroscopic friction coefficient. The macroscopic slip rule is found to exhibit a weak non-associativity in the tangential plane, although the slip rule at the microscale is associated in the tangential plane. Counterintuitive effects are observed for compressible materials, in particular, for auxetic materials.

Keywords:

Contact, Friction, Anisotropy, Roughness, Micromechanics

Affiliations:
Stupkiewicz S.-IPPT PAN
Lewandowski M.J.-IPPT PAN
Lengiewicz J.-IPPT PAN
3.Lewandowski M., Gajewski M., Jemioło S., The Material Anisotropy Influence on Modelling of Rutting Test with Application of Linear Viscoelasticity Constitutive Equations, Procedia Engineering, ISSN: 1877-7058, DOI: 10.1016/j.proeng.2014.12.020, Vol.91, pp.93-98, 2014
Abstract:

In the paper a general approach to modelling of anisotropic linear viscoelastic material properties is presented. Rychlewski's (1983) spectral decomposition theorem is used and one dimensional relaxation functions of linear viscoelasticity model is adopted to eigenvalues of stiffness tensor and named Kelvin relaxation functions. Proposed model was implemented in the FEM system Abaqus on the example of transversely isotropic and isotropic material. On the basis of experimental data available in literature, models were calibrated and verified. Constitutive relations were used in the complex boundary value problem modelling standard rutting test used in road sector to assess the resistance of asphalt mixtures to rutting.

Keywords:

constitutive modeling, viscoelasticity, finite element method, anisotropic materials, asphalt concretes

Affiliations:
Lewandowski M.-IPPT PAN
Gajewski M.-other affiliation
Jemioło S.-other affiliation