Research areas
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Basic mechanisms of creep, fatigue, brittle fracture and their combination in relation to microstructure of metallic materials and metal-based composites.
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Theoretical studies of crack behavior in metallic materials, metal-based composites and components.
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Multi-scale simulation of deformation and fracture processes, quantitative fractography and prediction of fatigue life under multiaxial loading.
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Solutions to problems related to fatigue, creep and brittle fracture of both currently applied and developed materials in industrial applications.
Main objectives
Properties of engineering materials have to be continuously improved in order to achieve heightened performance, safety and reliability in engineering systems. The main objective of the research group’s activities is to study the relationship between material structures and material properties, mainly mechanical. The research is aimed at fatigue, creep, their interaction, and fracture properties of advanced materials and metal based composites used or currently being developed for application in energetics, transport and medicine. The expected results cover both the generation of material data necessary for safe and reliable application of engineering structures and components in service, and the extension of basic knowledge in material damage mechanisms.
Content of research
To achieve the objectives specified in the preceding section, extensive investigation of the properties (predominantly mechanical) of selected advanced materials in relation to their microstructure is carried out. Another line of research activity is the study of mechanisms in degradation processes in advanced metallic materials and metal based composites under conditions simulating service loading.
Current specific research activities include:
Mechanical properties of advanced metallic materials
The research currently focusses on basic mechanisms operating in materials during creep, fatigue and brittle fracture and on their relation to microstructures. Mechanical tests performed include creep testing, fatigue testing, tensile testing, fracture tests, as well as combined tests; e.g. combined creep/fatigue experiments. After the project’s start-up period, which includes 2012, the research group will be sufficiently equipped with the required testing facilities so that the tests can be performed in a broad range of temperatures, strain rates and other external parameters. The corresponding know-how is already available. An integral part of the group’s research activity is in theoretical studies of crack behavior in metallic materials and components. These studies are based on standard computational methods such as FEM.
Microstructure, diffusion and thermodynamics of advanced metallic materials
Investigation of structures of materials in relation to their thermodynamic and diffusion properties. Structure is understood over a wide range of length scales starting with atomic bonds, through crystallographic lattice and its imperfections, to the size and morphology of crystallites (grains) in material. After the acquisition of all planned experimental facilities and equipment, particularly within the framework of the Core facilities (especially the high-resolution transmission electron microscope) the research group will have almost all the necessary equipment and the know-how for the investigation.
Multiaxial fatigue of advanced metallic materials
Research in this area primarily focusses on the elevated temperature behavior of advanced metallic materials used in highly stressed components of turbines and combustion engines, with a special focus on aeronautics. Nickel based superalloys or lightweight TiAl intermetallic alloys are often subjected to complex loading conditions due to external load transfer, abrupt changes in geometry, temperature gradients, and material imperfections. The acquisition of a computer controlled multiaxial testing system facilitating high temperature cyclic multiaxial straining allows the study of damage mechanisms and provides information to obtain pertinent parameters characterizing the resistance of these advanced materials. Materials will be subjected to similar strain and stress histories to those they would encounter in critical locations of components and structures in the transport and energy production industries. The changes in the mechanical response will be recorded and the modification of the internal structures and fatigue damage introduced by simulated complex loading situations will be studied using transmission and scanning electron microscopy and atomic force microscopy in order to improve the resistance of new advanced materials and predict their fatigue life under the most severe external conditions.
Multiaxial fatigue of materials with surface layers and shape-memory alloys
Current research involves multi-scale simulation of deformation and fracture processes, quantitative fractography and the prediction of fatigue life under multiaxial loading. The acquisition of the testing system for thermo-mechanical biaxial tests of metallic materials with surface layers will enable testing of wires and cylindrical specimens made of shape-memory materials. This is necessary to identify the proper temperature and strain parameters of shape-memory actuators, stents and other components of advanced medical devices based on the shape-memory effect.
