Publications

The paper presents the results of rheological testing performed with the use of DMA (Dynamic Mechanical Analyser) rheometer on specimens made of natural rubber (NR) and synthetic rubber (CR) elastomeric materials typically used for production of bridge bearings. The experiments provided the values of complex stiffness modulus and phase shift angles over a very wide temperature and frequency range, enabled determination of glass transition temperatures and plotting the master curves of the respective materials and, moreover, indentation tests were carried out with a spherical indenter pressed down with linearly increasing force. The test results can be used for both qualitative and quantitative evaluation of the materials and for determining certain mechanical parameters of linear viscoelastic constitutive models formulated for the infinitesimal strain theory. The indentation test was conducted to obtain values which can be used for indirect validation of constitutive hyperelastic and visco-hyperelastic models built up for continuum large deformation theory. Moreover, the paper partly evaluates the effect of long-term (natural) ageing of materials on their rheological properties.

No abstract is provided for this article.

The paper presents the assessment of the properties of high modulus asphalt concrete in low service temperature range. Such an assessment is particularly important due to the climatic conditions of Poland and the problem of the occurrence of thermal cracking in recent years. The scope of laboratory tests included both resistance to low temperature cracking according to TSRST method, but also other methods to characterize its strength properties and behaviour at low temperature. The indirect tensile strength characteristics and the thermal expansion coefficients were investigated. The analysis of the results included both the comparison of different mixtures, as well as the analysis of the probability of occurrence of pavement cracks, taking into account the minimum temperature in the layer defined on the basis of climatic data. Two mixture types were chosen for analysis: conventional asphalt concrete and High Modulus Asphalt Concrete. Either of them contained different bitumen types, including standard pen-grade bitumens, polymer-modified binders (PMB) and so-called highly-modified binders.

W pracy przedstawiono zagadnienie wpływu imperfekcji materiałowych i geometrycznych na techniczne zwichrzenie stalowych belek walcowanych i spawanych poddanych jednokierunkowemu zginaniu względem osi większej bezwładności przekroju y-y. Obliczenia metodą elementów skończonych przeprowadzono w odniesieniu do belek walcowanych na gorąco, wykonanych z kształtowników szerokostopowych HEB i wąskostopowych IPE oraz belek spawanych o takich samych proporcjach przekroju. Analizowano elementy o wstępnym wygięciu odpowiadającym pierwszej formie zwichrzenia oraz pierwszej formie giętnej względem osi mniejszej bezwładności przekroju z-z. Naprężenia resztkowe po walcowaniu i spawaniu elementów modelowano z użyciem wstępnych pól naprężeń. Wykonano geometrycznie i materiałowo nieliniowe analizy GMNIA. Do obliczeń numerycznych wykorzystano program metody elementów skończonych ABAQUS/Standard.

In this paper, a three-dimensional model of nonlinear elastic material is proposed. The model is formulated in the framework of Green elasticity, which is based on the specific elastic energy potential. Equivalently, this model can be associated to the deformation theory of plasticity. The constitutive relationship, derived from the assumed specific energy, divides the material's behavior into two stages: the first one starts with an initial almost linear stress-strain relation which, for higher strain, smoothly turns into the second stage of hardening. The proposed relation mimics the experimentally observed response of ductile metals, aluminum alloys in particular. In contrast to the classic deformation theory of plasticity or the plastic flow theory, the presented model can describe metal compressibility in both stages of behavior. The constitutive relationship is non-reversible expressing stress as a function of strain. Special attention is given to the calibration process, in which a one-dimensional analog of the three-dimensional model is used. Various options of calibration based on uniaxial stress test are extensively discussed. A finite element code is written and verified in order to validate the model. Solutions of selected problems, obtained via ABAQUS, confirm the correctness of the model and its usefulness in numerical simulations, especially for buckling.

This paper presents results of field tests performed in Poland within SPENS project. The test sections were built in Poland (October 2007). All of construction works as well as research tests were conducted in cooperation with the Swedish National Road and Transport Research Institute (VTI), STRABAG, TPA, Lafarge and ORLEN. The test section was divided into four parts of the same layer thickness, but with two different mixes in the base course: asphalt concrete and high modulus asphalt concrete. This allowed direct evaluation of the influence of high modulus asphalt concrete on pavement durability. Tests sections were subjected to accelerated loading test with use of the Heavy Vehicle Simulator. These tests were accompanied by field tests (Falling Weight Deflectometer and Ground-Penetrating Radar) and numerous of laboratory tests (binder content, grading, air voids, resistance to rutting, stiffness and fatigue). Investigation of fatigue damage development of asphalt layers is also presented. Four pavement structures with different binder courses made of: high modulus asphalt concrete with grains up to16mm and 20/30 binder, asphalt concrete with grains up to16 mm and binder 35/50 and fine graded anti-fatigue layer were compared using accelerated tests and also verification of applied design methods was made.