Papers by Dariusz Perkowski
Bulletin of the Polish Academy of Sciences Technical Sciences
The paper deals with the plane problem of an elastic layer resting on a Winkler foundation with a... more The paper deals with the plane problem of an elastic layer resting on a Winkler foundation with an emptiness. The stresses in the layer are caused by a given normal loading on its upper boundary plane. The mathematical formulation of the problem leads to a mixed boundary value problem and it is solved using Fourier transform methods and Fredholm integral equation of the second kind. The detailed analysis is derived analytically and numerically for an elliptic distribution of boundary loadings. The results for the normal displacement and the stresses on the lower boundary of the layer are presented in figures.
Materials
The integrity of delaminated composite structures can be restored by introducing a thermally-base... more The integrity of delaminated composite structures can be restored by introducing a thermally-based healing effect on continuous fiber-reinforced thermoplastic composites (CFRTPC). The phenomenon of thermoplastics retaining their properties after melting and consolidation has been applied by heating the delaminated composite plates above their glass transition temperature under pressure. In the current investigation, the composite is comprised of Methyl methacrylate (MMA)-based infusible lamination resin combined with benzoyl peroxide initiator, which polymerizes into a Polymethyl methacrylate (PMMA) matrix. For the reinforcement, unidirectional 220 gr/m2 glass filament fabric was used. Delamination damage is artificially induced during the fabrication of laminate plates. The distributed delamination region before and after thermally activated healing was determined by using non-destructive testing with active thermography. An experimental approach is employed to characterize the the...
Modelowanie Inżynierskie, 2010
Acta Mechanica et Automatica, 2007
Rozpatrzono przestrzeń będącą sprężystym kompozytem warstwowym o strukturze periodycznej osłabion... more Rozpatrzono przestrzeń będącą sprężystym kompozytem warstwowym o strukturze periodycznej osłabioną szczeliną prostopadłą do uwarstwienia. Zagadnienie zostało rozwiązane w ramach modelu homogenizowanego z parametrami mikrolokalnymi (Woźniak (1987), Matysiak i Woźniak (1987)). Do analizy zastosowano metodę transformacji całkowych i dualnych równań całkowych. Otrzymano rozkład przemieszczeń i naprężeń oraz współczynniki intensywności naprężeń. Zbadano wpływ własności mechanicznych oraz geometrycznych kompozytu na rozkład współczynnika intensywności naprężeń.
Proceedings of the 3rd World Congress on Mechanical, Chemical, and Material Engineering, Aug 1, 2021
International Journal of Heat and Technology, Oct 31, 2021
The paper deals with the thermoelastic problem of a multilayered pipe subjected to normal loading... more The paper deals with the thermoelastic problem of a multilayered pipe subjected to normal loadings on its inner surface and temperature differences on its internal and external surfaces. Two types of nonhomogeneous pipe materials of pipe are considered: (1) a ringlayered composite composed of two repeated thermoelastic solids with varying thickness and (2) a functionally graded ring layer. The ring-layered pipe with periodic structure is investigated by using the homogenized model with microlocal parameters. A homogenization approach is proposed for the modelling of the FGM pipe. The analysis of obtained circumferential, radial and axial stress is presented in the form of figures and discussed in detail. It was shown that the proposed approach to the homogenization allows us to correctly calculate the averaged characteristics in the representative cell (the macrocharacteristics) and also the characteristics dependent on the choice of the component in the representative cell (the micro-characteristics) for both microperiodic composites and functionally graded materials.
International Journal of Heat and Technology, 2021
The paper deals with the thermoelastic problem of a multilayered pipe subjected to normal loading... more The paper deals with the thermoelastic problem of a multilayered pipe subjected to normal loadings on its inner surface and temperature differences on its internal and external surfaces. Two types of nonhomogeneous pipe materials of pipe are considered: (1) a ring-layered composite composed of two repeated thermoelastic solids with varying thickness and (2) a functionally graded ring layer. The ring-layered pipe with periodic structure is investigated by using the homogenized model with microlocal parameters. A homogenization approach is proposed for the modelling of the FGM pipe. The analysis of obtained circumferential, radial and axial stress is presented in the form of figures and discussed in detail. It was shown that the proposed approach to the homogenization allows us to correctly calculate the averaged characteristics in the representative cell (the macro-characteristics) and also the characteristics dependent on the choice of the component in the representative cell (the m...
Acta Mechanica et Automatica, 2009
W pracy rozpatrzono zagadnienie kontaktowe dla półprzestrzeni kompozytowej z uwzględnieniem wytwa... more W pracy rozpatrzono zagadnienie kontaktowe dla półprzestrzeni kompozytowej z uwzględnieniem wytwarzania ciepła. Ośrodek materialny jest kompozytem warstwowym składającym się z dwuskładnikowych liniowotermosprężystych lamin powtarzających się periodycznie a brzeg ciała jest prostopadły do uwarstwienia. Nieodkształcalny stempel o przekroju parabolicznym porusza się ze stałą prędkością powodując wytwarzanie ciepła na skutek tarcia, które opisano prawem Coulomba. Ponadto założono, że stempel jest izolatorem cieplnym a całe ciepło przejmowane jest przez półprzestrzeń kompozytową. Poza strefą kontaktu założono brak obciążeń zewnętrznych oraz zerową temperaturę. Sformułowane zagadnienie rozwiązano w ramach modelu homogenizowanego z parametrami mikrolokalnymi, Woźniak (1987), Matysiak i Woźniak (1988).
Acta Mechanica et Automatica, 2007
Rozpatrzono przestrzeń będącą sprężystym kompozytem warstwowym o strukturze periodycznej osłabion... more Rozpatrzono przestrzeń będącą sprężystym kompozytem warstwowym o strukturze periodycznej osłabioną szczeliną prostopadłą do uwarstwienia. Zagadnienie zostało rozwiązane w ramach modelu homogenizowanego z parametrami mikrolokalnymi (Woźniak (1987), Matysiak i Woźniak (1987)). Do analizy zastosowano metodę transformacji całkowych i dualnych równań całkowych. Otrzymano rozkład przemieszczeń i naprężeń oraz współczynniki intensywności naprężeń. Zbadano wpływ własności mechanicznych oraz geometrycznych kompozytu na rozkład współczynnika intensywności naprężeń.
Materials, 2021
A unified approach is presented for constructing explicit solutions to the plane elasticity and t... more A unified approach is presented for constructing explicit solutions to the plane elasticity and thermoelasticity problems for orthotropic half-planes. The solutions are constructed in forms which decrease the distance from the loaded segments of the boundary for any feasible relationship between the elastic moduli of orthotropic materials. For the construction, the direct integration method was employed to reduce the formulated problems to a governing equation for a key function. In turn, the governing equation was reduced to an integral equation of the second kind, whose explicit analytical solution was constructed by using the resolvent-kernel algorithm.
This paper presents a novel approach to the analysis of nanofluids by using a nonlinear multifrac... more This paper presents a novel approach to the analysis of nanofluids by using a nonlinear multifractal algorithm. Multifractal analysis allows to present detailed local descriptions of complex scaling behavior using a spectrum of singularity exponents. Nanoliquids prepared from nanoparticles of SiO2 (~0,01g) suspended in 100 ml of demineralized water and in 100 ml of 99,5% isopropanol were subjected to classical methods of analysis: determination of the contact angle, determination of the zeta potential, pH, and examination with a particle size analyzer. The obtained results show that the obtained nanofluid is stable and well prepared, while further nonlinear analyzes show that the usage of multifractal analysis for nanofluids can significantly improve both the process of analyzing this issue as well as its preparation, based on the multifractional spectrum.
World Congress on Mechanical, Chemical, and Material Engineering, 2021
Contact problems of elastic solids are widely studied due to their engineering applications when ... more Contact problems of elastic solids are widely studied due to their engineering applications when considering contact of friction pairs or other processes related to the transfer of load from one body to another for both homogeneous and heterogeneous materials-including materials with structural gradation of properties or composites. For this type of materials, solving problems and describing mechanical properties often comes down to the use of various averaging methods, e.g. homogenization methods. One of the examples of such methods is the homogenization method with microlocal parameters used, among others, for heterogeneous composite materials. Author's main scope of research are composite materials with layered structureespecially microperiodic layered composites [1-4]. For this type of materials, solutions for layers perpendicular and parallel to the edge are widely known, and the inclined layering is still under investigation. This work presents a plane contact problem for the microperiodic composite half space with slant layering. Presented work discuss a contact of a rigid punch pressed into the composite body with normal forces in the state of limit equilibrium. Two punch shapes were consideredcylindrical and rectangular. Microperiodic composite under consideration is made from thin layers arranged periodically. Each layer is made of two homogenous components differing in their Young's modules. Presented problem has been solved analytically using the homogenized model with microlocal parameters and numerically using a FEM. Analytical results in the form of the contact pressures and stress distributions are presented for both components of the composite body in the integral form. The integrals have been computed numerically. Characteristics of maximum pressures and width of the contact zone are presented for different angles of stratification and for different stiffness ratios of composite components. The results are presented for both punch shapes. Authors are testing the applicability of the homogenized model based on FEM solutions, because analytical solutions under the classical theory of elasticity are almost impossible to obtain, and the time spent on it is too long. In the case of the per-component contact pressures it could be seen that their maximum values differ the more the higher stiffness ratios are, so considering only the averaged values is not justified and an approach that allows to determine the stresses in each layer separately should be usedas is possible with the homogenized model with microlocal parameters.
International Journal of Heat and Mass Transfer, 2011
The paper deals with a contact problem of a moving infinitely long punch on the boundary plane of... more The paper deals with a contact problem of a moving infinitely long punch on the boundary plane of vertically laminated half-space. The problem is solved within the homogenized model with microlocal parameters and under some physical assumptions. By using Fourier transforms the problem is reduced to a integral equation, which is solved numerically. The analysis of temperature and stress distributions and Barber's contact parameter is presented.
Heat and Mass Transfer, 2013
The paper deals with the two-dimensional stationary temperature distribution in a composite layer... more The paper deals with the two-dimensional stationary temperature distribution in a composite layer. The nonhomogenous body is assumed to be composed of periodically repeated two-layered laminae. The layering is inclined with an arbitrary angle to the boundary planes. The lower and upper boundary planes are assumed to be kept at given temperatures. The considered problem is solved within the framework of the homogenized model with microlocal parameters, where the continuity thermal conditions on interfaces are satisfied.
Acta Mechanica, 1992
The paper deals with surface waves propagating through a periodic two-layered elastic half-space.... more The paper deals with surface waves propagating through a periodic two-layered elastic half-space. The analysis is performed on the basis of a homogenized model with microlocal parameters. The velocity of the surface wave is obtained as a function of geometric and dynamic properties of the subsequent layers. The numerical examples illustrating the variations of the surface wave velocity are presented.
Acta Geophysica, 2014
The paper deals with the problem of SH harmonic wave propagation in an elastic layer with tempera... more The paper deals with the problem of SH harmonic wave propagation in an elastic layer with temperature dependent properties. The shear modulus and mass density are linearly dependent on temperature. The layer is rested on a rigid foundation and the upper boundary is free of loadings. The boundary planes are kept at different constant temperatures. The wave velocity and amplitude of stresses are analysed.
Journal of Mathematical Sciences
The paper deals with a plane elasticity problem for a composite half space subjected to frictiona... more The paper deals with a plane elasticity problem for a composite half space subjected to frictional contact. The half space is regarded as a microperiodic layered composite consisting of two components. The interfaces of layers are parallel to each other and oblique relative to the boundary of half space. A homogenized model with microlocal parameters is used to solve the considered problem. The solution is obtained in the general form and, specifically, for the case of elliptic loads [4]. On the basis of the obtained results, the maximum tensile stress is analyzed on the boundary of the half space and presented in the graphical form.
The paper presents an analysis of the influence of the shape of the rigid body pressed into the m... more The paper presents an analysis of the influence of the shape of the rigid body pressed into the micro-periodic composite half-space on the examples of two punch shapes – parabolic and rectangular. The presented material is a layered body that consists of infinitely many thin alternately arranged homogenous layers. Layers of the presented composite are oblique to the boundary surface. Two cases of punch tip shape are examined – parabolic and rectangular. The presented problem has been formulated within the framework of a homogenized model with microlocal parameters and solved using the elastic potentials method and averaged boundary condition. Fourier integral transform method has been used to obtain the solution and the inverse integrals have been calculated numerically. Solutions in terms of contact pressure and maximum pressure characteristics were shown in the form of graphs. Key ords: contact problem; micro-periodic composite; punch shape.
Uploads
Papers by Dariusz Perkowski