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Chair of Ceramics

Main Research

09/07/2011

Simulation of the mechanical and thermo-mechanical behaviour of building materials and refractories

The cost-effective application of building materials is of growing importance, thus measures for optimisations are still of special interest. Computational methods were used to predict the behaviour under their respective boundary conditions. The simulation of the thermo-mechanical behaviour of refractories represents a research area at the chair of ceramics.

Refractories were mainly used in industrial vessels to protect the steel construction from high process temperatures. Theses vessels are widespread, for example in metallurgical industry, glass industry, chemical as well as in the building materials industry. Based on their application, refractory materials reach temperatures of more than 1500°C. Mechanical stresses appear in the lining due to the thermal expansion and the mechanical constraints. These loads facilitate mechanical failure and can accelerate the wear rate of the refractory material and necessitate a premature replacement of the refractory product.

The behaviour of the lining can be improved with adequate selection of the materials, optimisation of geometry or adaptation of process parameters. For this purpose simulations using Finite Element Methods (FEM) are carried out at the chair of ceramics. To clarify failure mechanisms it is necessary to allow for nonlinear material behaviour especially in the course of crack formation.

With this numerical tool it is possible to analyse for example the loads in the bottom/wall transition zone of a LD-converter in which carbon-rich hot metal is converted into steel.

The thermal expansion of the lining in the bottom and the wall induces a bending moment in the bricks of the transition zone. At the right side of the figure the stresses in radial direction are shown in a contour plot. Zones with tensile stresses are red and zones with compressive loads are coloured yellow. These bending stresses lead to crack formation parallel to the hot face, which can cause spalling of brick parts.

References

D. Gruber, K. Andreev, H. Harmuth: Optimisation of the Lining Design of a BOF Converter by Finite Element Simulations. Steel Research int. 75 (7), 455-461, 2004