Institute of Mechanics and Fluid Dynamics Research Group Solid Mechanics

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1 Institute of Mechanics and Fluid Dynamics Research Group Solid Mechanics Prof.Dr.rer.nat.habil. Meinhard Kuna

2 Main research topics Fracture mechanical stress analysis and safety assessment of structural components Mechanics of materials and damage mechanics Smart mechanical systems Development of computational methods in fracture and solid mechanics Offered engineering service Fracture mechanical stress analysis of components (static, dynamic, cyclic, stochastic) Assessment of strength, reliability and life time Materials testing with small specimens and parameter identification Provision of numerical techniques (FEM, BEM) and software for fracture and damage mechanics Development and implementation of progressive user-specific material models Damage mechanics simulation of material failure (metal forming, crash, ) Further education seminars on Finite element methods in fracture mechanics

3 Technical equipment Experimental technique Universal materials testing machines AGS: max. force 10 kn and 250 kn Micro testing machine SHIMADZU-Micro-Servo-Pulser (max. 100 N, 0 60 Hz) Optical three dimensional deformation measurement system with object grating method ARAMIS Optical stress measurement systems VISHAY (light polarization in transmission and reflexion) Computational technique Compute server LINUX-Cluster with 10 nodes (each 16 CPU AMD Barcelona, 64 GByte RAM, Infiniband, 300 GByte disk) File Server 6 TByte, RAID, Backup system, USV Computer Pool FEM/CAD for students (10 High performance PC 2 CPU AMD Opteron, LINUX) Software FEM: ABAQUS, ANSYS, PATRAN own developed FEM, BEM and DEM codes MATLAB, Mathematica, CAD-systems a. o.

4 Fracture mechanical stress analysis and safety assessment of components Fundamental and applied research in fracture mechanics and classical theory of strength to evaluate the safety, reliability and life time of engineering constructions from nuclear power plants, gas pipelines, wind turbines, comminution machines, automotives and microelectronics. Development of failure criteria and assessment procedures. Development of fracture mechanics assessment system for high-pressure gas pipelines Safety evaluation of girth welds in the pipeline system of former east Germany Development of a fracture mechanics concept based on Failure-Assessment-Diagram FAD Interactive software tool, supporting the test engineer during non-destructive inspections of welds to evaluate detected defects in dependence on pressure, additional axial loads and eigenstresses. K r unsicherer Bereich (verfeinerter Modus) unsicherer Bereich (vereinfachter Modus) A Bewertungspunkt sicherer Bereich Grenzlinie verfeinert Grenzlinie vereinfacht L r

5 Fracture mechanical strength analysis of railway wheels from ductile cast iron ADI Verification of safety against static fracture and fatigue crack growth during design phase Deduction of tolerable crack size in connection with in-service inspection procedures Simulation of drop tests of nuclear shipping casks Safety design requires consideration of dynamic impact loading Development of computational tools to determine dynamic fracture mechanics loading parameters FEM-simulation of drop tests assuming hypothetical cracks in the casks

6 Smart mechanical structures In high-tech-branches as aeronautics, automotives, mechatronics and micro system technology one aims a smart, self-adapting behaviour of engineering constructions by combining structural, sensoric, actoric as well as controlling components. These recent developments need investigations by simulation of coupled mechanical, thermal and electromagnetical behaviour of the smart structures and the new smart composite materials. Electromechanical modelling of composites with integrated piezo ceramics Continuum mechanical analysis of internal electromechanical loading in smart piezoelectric fibre or layer composites to optimize the materials design CFRP 0 ISO PZT ISO CFPR 90 CFRP 0 metal electrode Development of analytical and numerical models to evaluate the electromechanical strength of interface cracks

7 Fracture mechanics of ferroelectric ceramics Development of numerical methods to compute intensity factors and energy release rates J ( h u D ) q dv ( hn t u c ) q ds kj ij i, k j k k, i k i i, k s, k k V S S Calculations to analyse and interpret fracture mechanical experiments with piezoelectrica Simulation of micromechanical processes at the crack tip, e. g. numerical and semi-analytical models of ferroelectric domain switching and its effect on fracture toughness

8 Materials modelling and damage mechanics Theoretical modelling and numerical simulation of micro structural processes during deformation and failure in techniqual materials using methods of constitutive thermodynamics theory, damage mechanics and homogenization. Application to optimization and evaluation of material properties during their production and under complex in-service conditions. Particularly, the brittle, ductile and the nil-ductile transition behaviour of failure in metals, ceramics and semi-conductors is studied. Identification of elastoplastic and damage parameters To apply plastic and damage mechanics material laws, determination of relevant parameters is needed (e. g. Gurson law) Measurement of displacement fields on notched tensile specimens by means of object grating method Identification of material parameters from measured inhomogeneous displacement fields and FEMsimulation using non-linear optimization algorithms

9 Determination of ductile deformation and failure properties by miniaturized Small-Punch-Test Surveillance of the local material state in structural components by minimal invasive removal of representative miniature specimens Mechanical loading of the specimens in a deep drawing test (SPT) until failure Determination of true yield curve and damage parameters (Gurson, Beremin) from test records by means of numerical simulation and neural networks

10 Solder joints in micro electronics Challenge of new lead free solder alloys in surface mounting technology Prediction of life time and reliability of solder joints under thermomechanical fatigue Development of viscoplastic material model for temperature dependent creep, cyclic plasticity and damage (by void growth) Spannung Dehnung Granular matter Numerical simulation of brittle granular materials under mechanical loading Application of finite element (FEM) and discrete element methods (DEM) Investigation of force distribution and brittle fracture Weibull parameters as function of statistical arrangement and properties of particles

11 Development of computational methods in solid and fracture mechanics Enhancements of numerical methods in solid mechanics (finite element method FEM, boundary element method BEM) for the analysis of crack problems, fo r implementation of damage laws and for treatment of coupled field problems. Finite element simulation of crack growth Simulation of crack growth requires adaptive remeshing of finite elements Development of effective numerical algorithms for automatic, error-controlled mesh adaptation Supply of computational tools for crack growth under mixed-mode-loading

12 Contact TU Bergakademie Freiberg Institute of Mechanics and Fluid Dynamics Lampadiusstr Freiberg Secretary: +49 (0) Prof. Dr.rer.nat.habil. M. Kuna: +49 (0) Telefax: +49 (0) Internet: Meinhard.Kuna@imfd.tu-freiberg.de Approach