Modelling failures of thermal barrier systems
Thermal barrier systems (TBS) constitute key innovations that guide gas turbine technologies. Since they have a multilayer structure, they offer a dual chemical or thermal functionality when deposited on actively cooled hot section components. They inhibit degradation of the underlying structural superalloy and prevent thermo-mechanical fatigue and oxidation. Common failures of TBS employed in gas turbine technologies are often caused by oxidation, ingestion of projectiles in the gas stream and chemical attacks by molten injected deposits. With the aid of experimental assessment and/or modelling techniques, all three types of failures have been investigated. Since modelling of oxidation induced failures is well established, emphasis was put on the study of the other two types of failures. On the basis of penetration mechanics related physical properties (forces and stresses) were connected to the kinetic energy of the impact. A suitable mapping scheme was developed and used for establishing the scaling relations that characterise various parameters. These include thresholds for material removal, the transitions between major mechanisms and certain aspects of material removal at kinetic energies above thresholds. For further info click at: http://www.materials.ucsb.edu/~nsf/(opens in new window)
