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Dr. Gerd Dobmann

 

Biography of Dr. GerdDobmann

 


Dr. GerdDobmann ishonored:

Dr.-Ing. E.h. by the school of electrical engineering of the University Kassel in 2005;

Prof. Ing. E.h. of the polytechnicalSelesian University, Glivice/Katovice in 2011

Roy Sharpe Award 2011 by the BINDT in 2012


Development, EducationandQualification:

Thesis (Diploma) 25.02.1974

In Applied Physics and Electrical Engineering, Theoretical Electrodynamics: 'The calculation of the electromagnetic field of a vertical electric dipole on a periodic rough earth surface'.

Termination of the studies with the grade 'excellent'.

1974

Start with research activities in the Fraunhofer Society, Institute for Non-destructive Testing (IZFP) in co-operation with the University of the Saar region, Theoretical Electrodynamics and Application to Electromagnetic Techniques in NDT.

1975 PhD-Thesis begin:

'Theoretical-numerical and experimental investigations to the application of the electrical direct current potential drop techniques in NDT'

1976

Employee of the Fraunhofer Society, head of a scientific working group 'Electrical, Magnetic and Thermal Techniques in NDT'.

1978

Head of the department 'Electromagnetic Techniques in NDE' in the IZFP.

16.02.1979 PhD-Thesis end:

Ph.D. in Applied Physics with the grade 'magna cum laude', i.e. 'excellent'


Memberships:

Member of the Committee “Pressurized Components and

Materials” of the German Nuclear Safety Commission up to 2011

Member of the advisory committee of the German Ministry ofEconomy and Technology in the nuclear safety program up to 2010

Member of the German NDT Society

Member of the ASNT, ASTM, AIST, ASM

Fellow of the Indian NDT Society

Fellow of the Institution of Engineering and Technology, IET

German Delegate in the International Institute of Welding (IIW) up to 2011

Chairman Commission V of IIW 1999-2008

Chairman Subcommission VE, electric, magnetic and thermal inspection of welds in IIW up to 2011

Subject Editor of the Journal NDT&E International of Elsevier Publishing


Project Experiences:

With priority R&D projects in the German Nuclear Safety Research Program to Improvement of existing and development 2 of new NDT techniques for detection, classification and sizing of material inhomogeneities (defects) as well as for materials characterization; characterization of ageing phenomena as thermal ageing, creep, fatigue (Low Cycle and High Cycle Fatigue), superposition of LCF and thermal ageing, neutron embritlement. Experiences with plain carbon steels, martensitic and bainiticsteels for pressure vessels and piping, austenitic stainless steels and Ni-alloys; high temperature materials as X20 CrMoV 12 1 and P91.


Dr. GerdDobmann will give a lecture on:


R & D to Electromagnetic NDT in the German Nuclear Safety Research Program – Material Characterization of Ageing Phenomena and Online Monitoring of Fatigue and Fracture‐Mechanical Tests


Obviously it is a fact: The nuclear energy technology worldwide was an important driver for thedevelopment of NDT/NDE. This is true in Germany too. Concerning the most relevant task of NDT –detection, classification, and sizing of material irregularities (inhomogeneities, defects) thedevelopment of NDT technologies and methodologies like UT and imaging with phased arraytransducers or defect reconstruction algorithms like SAFT (synthetic aperture focusing technique) orET of steam generator heat exchanger tubes with eddy current probes and multi‐frequencyapproaches primarily were in the focus of R&D.


However, in Germany there was also a strong demand to develop NDT for characterizing thematerials of the nuclear components in their properties. The basic idea was to have NDT technologyavailable for inservice inspection of primary circuit components which can characterize themicrostructure as well as load‐induced and residual stresses. The characterizing should be performedin terms of mechanical properties as hardness, strength like yield and tensile strength but alsotoughness properties like Charpy energy and fracture appearance transition temperature.


Beginning in 1976, the 3MA. Methodology (Micromagnetic, Multiparameter, Microstructure andStress Annalysis) was developed. 3MA has its basis in micromagnetic NDT techniques which are themeasurement of magnetic Barkhausen noise, of the magnetic incremental permeability, of the eddycurrent impedance, the harmonic analysis of the magnetic tangential field strength, and themeasurement of the dynamic or also called incremental magnetostriction. All of these techniques askfor a local magnetization in a hysteresis loop of the material under inspection and therefore 3MA canonly be applied at ferromagnetic materials. The techniques collect information which is generated byinteraction of Bloch walls with microstructural parameters (lattice defects as vacancies, dissolvedatoms, dislocations, precipitations, grain and phase boundaries as well as stress fields). Themagnetization processes utilized are reversible and irreversible. Therefore the information collectedis divers and redundant which helps to enhance the statistical significance for prediction and tusuppress disturbance influences. 3MA was applied to characterize ageing phenomena in pressurevessel and pipeline steels as thermal ageing and neutron degradation as well as material states whenthermal ageing and low cycle fatigue were superimposed. In the case of characterizing materialstates of austenitic stainless steels it strongly depends on the chemical composition whether thematerial – for instance when exposed to mechanical static or cyclic loads – reacts localized withphase transformation to bcc α’ martensite or not. The phase‐transformed microstructure isferromagnetic and therefore 3MA techniques can be applied. In all other cases UT is applied and‐forinstance a time‐of‐flight‐measurement – is the tool to characterize cyclic deformation. When themechanical loading is at elevated temperatures (300°C) EMAT are applied.


Monitoring of mechanical‐technological destructive tests by NDT technology can significantly