ên13th International Conferenceon Fracture June 16–21, 2013,Beijing, China -1- PaperTemplatefor 13th International ConferenceonFracture Yina F. M.Moscoso1, Anderson S. Barbosa2,João B. Uchôa3,Luciano M. Bezerra4, Marcus Sa5 1,2,3,4,5 Departamento de Tecnologia,Universidade de Brasilia, Cep:70910-900, Brasil Eletronic account:yifemunoz@gmail.com Abstract Ceramic coatings are generally used on the facades of buildings. These materials provide acoustic and thermal insulation, achieving a reasonable comfort in buildings. The coatings are run in layers: plaster, adhesive mortar, grout and ceramic. They are subject to different weather and thus prompted the actions coming from sudden temperature variation or thermal shock. When you combine these actions with different physical and mechanical characteristics of the materials used, states of stress and strain on the facades are produced, creating different pathologies, such as peeling parts, which can cause accidents on pedestrians. This paper presents a methodology for evaluating the fatigue resistance, using experimental, analytical and numerical analysis via Finite Elements and considering the system under the action of heat loss shock temperature characteristic in the city of Brasilia. Studies are in particular the influence of thermo mechanical stresses in fatigue failure of the adhesive mortar. Experimentally a Whöler curve (or "SN" curve) is obtained for the adhesive mortar. With the appropriate models for fragile materials, the fatigue strength of the mortar under compressive and tensile-compression is deduced. With the values of temperatures and correspondent stresses obtained via analytical and numerical analysis it is possible, with this methodology, to assess the fatigue resistance of the adhesive mortar on the coating system. Keywords: Fatigue coating, Coatingsystem, Stress facades 1. Introduction Coatings on facades of buildings are used, among other purposes, for protection against the weather which have aggressive agents that reduce its lifespan. They also, have the property to give thermal and acoustic comfort to the user inside the building. Thus, the facades are exposed to various situations of thermal loads, arising from changes in temperature and isolation, which results in thermal stresses requested by the materials that make up the coating. A ceramic coating system is an element for presenting different materials in different applications that must always maintain a balance between the stresses acting on the system and tension resistance of the materials so as not to compromise the integrity of the facade. In this paper we present the stresses inside the structure produced by outside thermal shock, when using clearceramic (low energetic absorption of heat) and dark ceramic (high-energetic absorption of heat), evaluating the structure performance against thermal shock cycles, which cause fatigue. The fatigue is evaluated by tracing the experimental curve or Wöhler SN, based on the principle that the thermal stresses acting on the system tend to cause their rupture by fatigue and using a coating structure composed of ceramic pieces and groutconstituting the outermost layer, connected with a thin layer of adhesive mortar in turn connected to a base composed of plaster. These structures are superposed on a masonry wall, which is coated with a layer of plaster facing the inside of the building. We tried to represent such a constructive disposition commonly used in Brazil.
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