Dr. Steffen Brinckmann

Ruhr University Bochum, ICAMS
Stiepeler Str. 129, 44801 Bochum

Phone: (0234) 32 - 293722982
Email: Steffen.Brinckmann ( a  ) rub , de

RESEARCH EXPERIENCE

• Multiscale Modeling

• Tension of nano-pillars: Design and etching of tensile grips; design and production of specimens
• Compression of nano-pillars: Production of nano-pillars in Au and Cu, mechanical testing of these specimens;
  perform novel in-situ deformation and correlate recorded movie to stress-strain curve;
  statistical evaluation of slip events in nano-pillars using self written C++ program

• Invented and applied a first order strain gradient model: Dislocation Density based Strain Gradient Model; analytically predicted power-law like hardening, numerically predicted size effect in porous materials
• Invented and employed a damage model for cohesive surfaces which is based on the microstructural properties of dislocations; numerically predicted experimental observations in fatigue of metals: fatigue threshold, Paris-law fatigue crack growth rate, retardation of crack growth after overload
• Constructed testing equipment and executed experiments on environmental degradation of adhesive bonds; implemented a computational model in the finite element package Abaqus; compared the numerical and experimental results
• Created experimental setup (bought hydraulic press and other supply) and performed compaction experiments on powders using a Material Testing System; performed X-ray measurements and calculated density of powder pellets; built an analytical framework for material property identification; implemented a material model into finite element package Abaqus

EDUCATION

FACULTY PREPARATION COURSES

TEACHING EXPERIENCE

• Lectured, graded exams; developed and graded quizzes for a class of 77 students
• Supervised teaching assistant, discussed homework grading, discussed penalty for homework plagiarism
• Held weekly (1 hour) and by request office consultation to discuss homework and student performance

• Lectured class of ~50 students when Prof. Siegmund was absent

• Instructed and assisted ~10 student to implement numerical solutions to physical example problems; debugged their programs
• Quizzed students on their solutions to determine level of understanding of physical and numerical problems

• Prepared and solved mechanical example problems weekly in front of class of ~20 students
• Graded exams

MENTORING

• Daily discussions on progress; determined tasks and milestones; assisted if problems occured
• Explained mechanics and numerical methods; wrote standard operating procedures
• Initiated creativity by giving freedom for weekly self-determined research

• Daily discussions on progress; determined tasks and milestones; assisted if problems occured and corrected mistakes

PUBLICATIONS

• A Cohesive Surface Model based on the Stress caused by Dislocations, S. Brinckmann, T. Siegmund, (submitted).
  
• A Fatigue Crack Initiation model incorporating Discrete Dislocation Plasticity and Surface Roughness, S. Brinckmann, E. Van der Giessen, (in press at International Journal of Fracture).
  
• Fundamental differences in mechanical behavior between two types of crystals at nano-scale, S. Brinckmann, J.Y. Kim, J.R. Greer, (in press at Physics Review Letters).
  
• Computations of fatigue crack growth with strain gradient plasticity and an irreversible cohesive zone model, S. Brinckmann, T. Siegmund, Engineering Fracture Mechanics, Vol. 75, pp 2276-2294, 2008.
  
• Environmental Degradation of the Cohesive Strength of Adhesives: Experiments and Numerical Simulation, S. Brinckmann, T. Siegmund, Proceedings of the 21st Annual Meeting of American Society of Composites, paper number: 197, 2006.
  
• A Dislocation Density Based Strain Gradient Model, S. Brinckmann, T. Siegmund, Y. Huang, International Journal of Plasticity, Vol 22, pp 1784-1797, 2006.
  
• Fatigue Crack Growth Simulations with Length Scale Dependent Material Laws, S. Brinckmann, B. Wang, T. Siegmund, Proceedings of the 9th International Fatigue Congress, 2006.
  
• On the Role of Dislocations in Fatigue Crack Initiation, S. Brinckmann, Ph.D. thesis, ISBN 90-367-2237-3, 2005.
  
• Dislocation Structures Leading to Fatigue Crack Initiation, S. Brinckmann, E. Van der Giessen, Proceedings of the 25th Risoe International Symposium on Materials Science, 2004.
  
• A Discrete Dislocation Dynamics Study Aiming at Understanding Fatigue Crack Initiation, S. Brinckmann, E. Van der Giessen, Materials Science and Engineering A, Vol 387-389, pp 461-464, 2004.
  
• Stress Concentration at the Surface of Fatigued Materials: A Discrete Dislocation Dynamics Study, S. Brinckmann, E. Van der Giessen, Proceedings of the International Conference on Computational & Experimental Engineering and Sciences, 2003.
  
• Towards Understanding Fatigue Crack Initiation: A Discrete Dislocation Dynamics Study, S. Brinckmann, E. Van der Giessen, Proceedings of the 9th International Conference on the Mechanical Behavior of Materials, 2003.
  

ORAL PRESENTATIONS AT INTERNATIONAL CONFERENCES

• In-situ Observation of Mechanical Deformation in Nano-Pillars, ID-number: 423339, Materials Research Society Spring meeting, San Francisco (USA), 03/2008.
• A Micromechanical based Cohesive Surface Model, MCMAT2007-30528, American Society of Mechanical Engineers - Applied Mechanics and Materials Conference, Austin (USA), 06/2007.
• Fatigue Crack Growth in Metals: A Strain Gradient Simulation, IMECE2006-13678, American Society of Mechanical Engineers Congress, Chicago (USA), 11/2006.
• Environmental Influence on Crack Growth in Adhesives, IMECE2006-13680, American Society of Mechanical Engineers Congress, Chicago (USA), 11/2006.
• Environmental Degradation of the Cohesive Strength of Adhesives: Experiments and Numerical Simulation, American Society of Composites Congress, Dearborn (USA), 09/2006.
• Damage Evolution in Cohesive Surfaces based on the Degradation of the Surrounding Material, 7th World Congress on Computational Mechanics, Los Angeles (USA), 07/2006.
• A Fatigue Crack Initiation Model based on Dislocation Dynamics and a Cohesive Surface Model, 9th International Fatigue Congress, Atlanta (USA), 05/2006.
• Fatigue Crack Growth Simulations with Length Scale Dependent Material Laws, 9th International Fatigue Congress, Atlanta (USA), 05/2006.
• Simulation of Fatigue Crack Growth using the Dislocation Density based Strain Gradient Model, American Society of Mechanical Engineers Congress, Orlando (USA), 11/2005.
• Cohesive Zone Modeling of Fatigue Crack Growth, Abaqus Fracture Review Team meeting, Providence (USA), 09/2005.
• Fatigue Crack Initiation, Netherlands Institute of Materials Research, Annual Conference, Noordwijkerhout (The Netherlands), 12/2004.
• Stress Concentrations caused by Dislocations at the Free Surface, 21st International Congress of Theoretical and Applied Mechanics, Warsaw (Poland), 08/2004.
• A Dislocation Dynamics Study aiming at understanding Fatigue Crack Initiation, 13th International Conference on the Strength of Materials, Budapest (Hungary), 08/2003.
• Stress Concentrations at the Surface of Fatigued Materials: A Discrete Dislocation Dynamics Study, International Conference on Computational & Experimental Engineering and Sciences, Corfu (Greece), 07/2003.
• Fatigue Crack Initiation, Materials Science Conference, Veldhoven (The Netherlands), 05/2003
• Towards Understanding Fatigue Crack Initiation: A Discrete Dislocation Dynamics Study, International Conference on the Mechanical Behavior of Materials, Geneva (Switzerland), 05/2003.
• Towards Understanding Fatigue Crack Initiation: A Discrete Dislocation Dynamics Study, International Conference on Fatigue 2002, Stockholm (Sweden), 06/2002.

WORK EXPERIENCE

• Observation of construction work and discussion of construction procedures with construction supervisor

• Construction work (pouring concrete, building and setting up scaffold) on bridge building sites (water-wayl and train bridge)

AWARDS

PROFESSIONAL MEMBERSHIPS

COMMUNITY SERVICE

SKILLS