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N.C.S.R. "Demokritos"

Research

Department of Materials Science

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Computer simulations of the performace of archaeological ceramics

Ceramics have always been, and still were up to the middle of the 20th century, the most common material for a large variety of applications in daily life as they fulfilled miscellaneous functions. Pottery vessels have been used mainly for storage, transport and cooking. Fine ceramics have been used as tableware but also for purely decorative purposes. Furthermore, ceramics have been used as tools in technological applications, such as metallurgy or glass production, and construction. Ceramics have become so popular not only due to the wide availability of raw materials, but due to some basic properties which were advantageous in all this applications. First, due to its plasticity the unfired clay paste is easy to form and practically any possible shape can be fabricated. Secondly, with firing, ceramic material becomes hard and extremely resistant to environment and use. In this context, the most important properties induced with firing are strength, toughness, impermeability and heat resistance.

Diverse functions, however, required a variety of properties for different ceramic products. While the use of vessels as transport containers, for example, required high fracture strength of the material cooking pots had to withstand thermal stresses and to provide an optimum heat transfer from the fire into the interior. Furthermore, the contents of storage or transport jars were decisive for particular properties. For example, liquids required usually impermeable walls perhaps with the exception of water jars, for which high porosity helped to cool down the water. The respective material properties could be achieved with modification of clay paste and with appropriate firing technology. However, the clay paste itself was only one component of the actual ceramic structure, with the others being non-plastic inclusions and voids or pores.

Apart from the nature of the clay paste components and the firing conditions, another parameter that affects the mechanical and thermal performance of the ceramic vessels is the shape and geometric characteristics. Important parameters are the wall thickness, the vessel size, the curvature and the existing angles in its form. Furthermore, the performance is dependent on the points of load, i.e. the areas at which mechanical or thermal loads are actually affecting the vessel. It is, therefore, apparent that the design of a vessel is an important parameter for the assessment of technology and in this context a continuous diachronic change in the design can be observed. Experimental testing of the mechanical properties of the material and the effect of shape on the performance of actual archaeological vessels is beyond question as long as these measurements are linked with destruction of the object. Nevertheless, considering particular material properties, which can be determined in the laboratory, in combination with shape a computer model of the vessel can be generated. By using the finite element method (FEM) mechanical or thermal loads can be applied to the model in a computer simulation and it is possible to assess the performance of the vessel and to predict consequently critical loads, which could cause failure of the vessel.

Recent work at the Institute of Materials Science concerned for example the influence of shape on the performance of transport vessels during their use. A case study of Hellenistic transport amphorae from Kos indicated that the development of their shape was related with an improvement of strength. Another subject was the thermal performance of Bronze Age metallurgical ceramics. Models were designed on two levels, the texture and microstructure of the ceramics and the entire structure, for example, of copper smelting furnaces. The results of the simulations showed considerably small levels of thermal conductivity of the examined ceramics. On the basis of the furnace models the operation condition could be assessed as well as the influence of different material parameters on the thermal efficiency of the metallurgical ceramics.

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for more information: Anno Hein

Relevant journal articles

  • Hein, A., Georgopoulou, V., Nodarou, E., Kilikoglou, V. (2008) Koan amphorae from Halasarna - investigations in a Hellenistic amphora production centre, Journal of Archaeological Science 35, 1049-1061.
  • Hein, A., Kilikoglou, V. (2007) Modeling of thermal behavior of ancient metallurgical ceramics, Journal of the American Ceramic Society 90, 878-884.

  • Relevant publications in proceedings

  • Hein, A. and Kilikoglou, V. (2008) Finite element analysis (FEA) of metallurgical ceramics, Assessment of their thermal behaviour, Aegean Metallurgy in Bronze Age (ed. I. Tzachili) Ta Pragmata, Athens 305-314.
  • Hein, A. and Kilikoglou, V. (2007) Assessment of ancient vessel design with the Finite Element Method (FEM), Archaeometric and Archaeological Approaches to Ceramics (ed. S.Y. Waksman) BAR International Series 1691 9-12.
  • Department of Materials Science, N.C.S.R. "Demokritos", 153 10 Aghia Paraskevi, Attiki, phone: +30 210 6503381, fax: +30 210 6519430
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