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Analysis of selected properties of asphalt concrete with synthetic wax

Mazurek G., Iwański M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2018

Vol. 66, nr 2

217--228

This article discusses the issue of viscoplastic deformation that usually occurs in road pavements, especially in the summer season in Poland. The evaluation of viscoplastic deformations was performed on the example of the asphalt concrete designated for the binding course layer (AC16W). Additionally, the bitumen used for manufacturing asphalt concrete samples was modified with two types of synthetic waxes widely applied in the warm mix asphalt technology. These waxes varied in molecular weight, which affected their softening point results. Before decomposition of the total strain into elastic and viscoplastic part, oscillatory tests in the linear viscoelastic region were required. The generalized Maxwell model was used to describe the behavior of asphalt concrete in the linear viscoelastic range. Using the elasto-viscoelastic correspondence principle, described by Schapery, the initial yield strength stress was evaluated. The pseudostrain variable turned out to be useful for estimating the onset of viscoplastic strains occurring in road pavement. Such engineering procedure approach could result in faster approximation of the yield strength level during the design of pavement structures. It will also allow for differentiation of mixtures in terms of their susceptibility to permanent deformation and of their sensitivity to traffic induced overloading.

The conception of the fatigue model for layered composites considering thermal effects

Katunin A.

Archives of Civil and Mechanical Engineering

2011

Vol. 11, no 2

333-343

Polymer-based layered composites are widely used in many responsible applications, such as turbine blades, helicopter propellers etc. Therefore its behaviour must be predictable in different conditions and operational states. Dynamic excitation of polymer composites obliges to consider it as a viscoelastic material, which introduce additional phenomena, e.g. self-heating effect. This effect occurred into two states: steady and non-steady. The strain of the structure subjected to the self-heating could be evaluated basing of DMA measurements and using Arrhenius kinetic concept together with time-temperature superposition principle. For obtaining the fatigue model the pseudo-strain approach was used. The fatigue model was based on damage function with taking into consideration self-heating effect.

Polimerowe kompozyty warstwowe są szeroko stosowane w wielu odpowiedzialnych aplikacjach takich, jak łopatki turbin, śmigła helikopterów itd. Z tego względu ich zachowanie powinno być przewidywalne w różnych warunkach i stanach operacyjnych. Dynamiczne wzbudzanie kompozytów polimerowych obliguje do rozpatrywania ich jako materiału lepkosprężystego, co powoduje dodatkowe zjawiska, np. efekt samorozgrzania. Efekt występuje w stanie ustalonym i nieustalonym. Odkształcenia struktury pod działaniem efektu samorozgrzania mogą być określone w oparciu o pomiary DMA oraz z zastosowanie kinetycznej zasady Arrheniusa i zasady superpozycji czasowo-temperaturowej. W celu otrzymania modelu zmęczeniowego posłużono się metodą pseudo-odkształceń dla opisu lepkosprężystości. Model zmęczeniowy bazuje na funkcji zniszczenia z uwzględnieniem efektu samorozgrzania.