Materials Behavior and Materials Modelling

- Tasks / Main focus
- Special facilities
- Contact person

Department 52 Materials Behavior and Materials Modelling is subdivided into the following Units:

  • Unit 521  High Temperature Materials Testing
  • Unit 522  Material Models and Microstructure Calculation
  • Unit 523  High-Speed Loading

The individual topics are closely linked to each other. The basic idea is the close connection between experiment and simulation in order to provide problem-related data and adapted material models.

High-temperature materials testing means to represent the material behaviour at high temperatures with appropriate experiments. In general, time-dependent inelastic deformation plays a key role in the high temperature regime. It must be monitored using high-precision measurement devices in order to harness them as a basis for the adjustment of material models and assessment procedures. This includes the conduction of standard uniaxial specimen tests with static, dynamic or overlaid loading situation at high temperatures. The Unit of High- Temperature Testing therefore has the aim of improving the lab equipment in order to develop and enable specialised test procedures. Of course, this comes along with new up-to-date control systems and software which represent an optimum between flexibility and stability of test procedures. The used control systems and software have been developed together with the test machine company and they have also been tested for robustness. Using specialised application tools, deformation and stresses can be monitored exactly and made visible in order to validate the applied material models and design procedures. The requirements are set by the given tasks of industrial applications or research projects. Tests also can be done on components applying complex loading from forces, inner pressure or bending moments. The set-up of the component tests is usually fully developed and realised in-house.
Furthermore, the behavior of materials does not only consist of the description of defect-free specimens, but it also includes the description of crack initiation and crack growth. For this purpose, the latest measurement techniques are applied. Overall, the excellence of the Unit is to provide the customer with the appropriate and fitting solution to his given task. This may also include consulting services in problem solution.

The main task of the Material Law and Microstructure Calculation Unit is to describe the processes and mechanisms during loading and to analyse them on different scales. The understanding of the interaction between the given microstructure of the material and the deformation and damage behaviour allows a reliable estimation of the lifetime of components and forms the basis for “tailor-made” materials with the desired properties. The main activities of the Material Simulation Unit are in the field of atomistic and micromechanics, multi-scale modelling and optimisation of the material description. Other key aspects are the provision and maintenance of new material and damage models based on experimental approaches applicable for nearly all practical loading situations (static and dynamic) and temperatures up to the creep regime. The numerical simulations of materials carried out in the unit ranges from the atomic scale, over micro- and meso-scale up to macro-scale to register the impacts of microstructure in terms of hierarchic materials modelling. The aim is to link the numerical simulations with insights of the material science. Especially with respect to the macroscopic scales, the transferability of these findings to the component is in the focus of the model development. Calculation models and concepts applicable on component assessment are provided for this purpose. The main materials analysed are: metals, metallic alloys, single-phase and multiphase materials as well as related fibre- and particle-reinforced composite materials and layer compounds.

The Unit of High-Speed Loading applies loading rates up to 20m/s as well as impact loads on simple specimens and on components and structures. The analysis of the material and component behaviour at those loading rates is essential for safety analysis and also the simulation of manufacturing processes. Therefore, the load change and especially the deformation must be measured precisely with a high measurement rate. For this purpose, classical electrical strain gauges with a measurement rate of 1 MHz or optical tools, such as high-speed cameras with frame rates up to 2 million   frames/sec are used. Besides the assessment of integer components, high loading rates play an important role for structures with defects and cracks. For this purpose, research projects joint together with industry partners are done in the field of damage mechanics at pre-cracked structures, conducting dynamic fracture toughness tests on classical specimens but also on heavy lot specimens. Additionally, a Hopkinson bar for the upper speed range is available. The tests on specimens and components are then modelled by the Finite-Element-Method(FEM) through which application-specific concepts and methods can be developed.

Messung von lokalen Verformungen in gekerbten Proben
Messung von lokalen Verformungen in gekerbten Proben
Tasks / Main focus
Research
  • Microstructural investigations on real microstructures and derivation of relevant parameter for material law development
  • 2D/3D modelling of the material behaviour based on microstructural effects
  • Dynamic fracture mechanics
Development
  • Development of solutions for component tests at high temperatures
  • Improvement of material laws and damage mechanics approaches
  • Improvement of Finite-Element modelling
  • Linking of process-simulation and micromechanics
Fallwerk FE-Analyse
20kJ Fallwerk
Prüfung bei 1100 oC
Testing / Determining
 
  •  Creep tests according to DIN EN ISO 204, up to 1100°C and 100 kN
  •  Hot tensile tests according to DIN EN ISO 6892-2 up to 1100°C and 200 kN
  •  Relaxation tests according to 10319-1 / 2, up to 1000°C and 100 kN
  •  LCF-tests according to ASTM E 606 up to 1100°C and 100 kN
  •  High speed tensile tests according to DIN EN ISO 26203-2, between -100°C and 300°C
  •  Fracture toughness tests according to e.g. ASTM-E- 1820 between -150°C and 1000°C
  •  Pellini-tests according to ASTM-E 208
  •  Measurement of creep crack growth according to ASTM E 1457
  • Component tests up to 1000°C, inner pressure of 600 bar and up to 5 MN
Investigations / Analyses
  • FEM-calculation under application and derivation of
       -  standard material models
       -  user-defined material routines
       -  description of effects of creep and creep fatigue
  • Description of crack growth
  • FEM-analyses of high speed loadings
  • FEM-analyses of detonations
  • Molecular dynamics modelling and multi-scale simulations
Optische Verformungsmessung
Optische Verformungsmessung
Consulting Service
  • Conduction of tests for material qualification
  • Support in definition of test amount and test options
  • Analysis of component behaviour in the focus of high temperature and high speed loading
  • Organisation of seminars and training courses
Cooperation in Committees
  • Test facility for the research community of temperature resistant steels and high temperature materials (FVWHT)
  • European-Collaborative-Creep-Committee (ECCC)
  • ISO/TC 164 “Mechanical testing of metals”
  • ISO/TC 164/SC 01/WG 07 "Tensile testing at high strain rates"
  • ISO/TC 164/SC 04 “Toughness Testing”
  • ASTM Committee E08 on Fatigue and Fracture
  • NA 062 DIN-standards committee (NMP)
  • NA 062-01-42 AA working committee for tensile and ductility testing of metals
  • NA 062-01-46 AA working committee for fracture mechanics
Polykristallvernetzung Messung des Rissfortschritts
Kristallplastische Vernetzung eines Polykristalls
Messung des Rissfortschritts
Courses
  • Bachelor and Master thesis
  • Internships
Information
  • DAkkS-accredited for the tests mentioned above
Special facilities
  • Large scale testing up to 2.5 m in length and up to 700°C
  • Large tensile test machines up to 5 MN
  • Corrosion testing in supercritical steam
  • Dynamic strain-controlled tests with inner pressure loading
Further Information
Contact person

Secretary

Mrs. D. Dosch



 ++49 (0)711/685-63063
 

Head of Department

Mr. Dr.-Ing. A. Klenk



 ++49 (0)711/685-63968
 ++49 (0)711/685-63053
 

Units

High Temperature Materials Testing



Mr. Dipl.-Ing. J. Schleyer




++49 (0)711/685-62528

Material Models and Microstructure Calculation

Mr. Dr.-Ing. U. Weber

Mrs. Dr. rer. nat. E. Soppa

++49 (0)711/685-63055

++49 (0)711/685-63056

High-Speed Loading

Mr. Dipl.-Phys. U. Mayer

Mr. Dipl.-Ing. S. Offermanns

++49 (0)711/685-62607

++49 (0)711/685-62748