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Engineering Design and Product Reliability

Former Staff

Prof. Dr.-Ing. Heinz Mertens

© Heinz Mertens

1981 - 2004 Head of the Chair of Design Theory at the Institute of Design and Micro and Medical Technology

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Areas of research

  • Engineering design
  • Design against stress
  • Drive systems and components
  • Service life and fatigue strength predictions

Fields of specialization

  • Drive Systems and Components
  • Simulation
  • Computer-aided design for strength and vibration problems and model development

Gregor Schilling, M.Sc.

Research associate 04/2017 - 04/2023

  • Teaching:
    • Rotor Dynamics
    • Balancing Techniques
    • Engineering Design 2
    • Supervised term papers, projects, and bachelor’s and master’s theses

Tobias Werder, M.Sc.

Research associate 08/2016 - 09/2021

Area of research

SFB-1029/2

TurbIN - Substantial Efficiency Increase in Gas Turbines through Direct Use of Coupled Unsteady Combustion and Flow Dynamics

Subproject B01:

Active flow control of stator cascades at periodically-transient boundary conditions

Dr.-Ing. Hanns Michel

Research associate 09/2015 - 09/2020

 

Area of research

Thermal examination of gas foil bearings

Gas foil bearings (GFBs) are innovative machine elements used to support high-speed rotors without contact on an aerodynamic air film. In this thin air film, sufficiently high pressures are generated at corresponding speeds to support the rotor. The advantages of no lubrication, the possibility of very high speeds, robust temperature behavior and a long service life make the use of GFBs particularly interesting for turbomachines.

As the pressure film builds up, internal friction in the air film causes heating. As the temperature rises, key properties of the air change, such as thermal conductivity and viscosity. Modeling the heat flows in a gas film bearing therefore contributes to understanding how to operate and model a gas film bearing. A numerical model will be used to investigate these heat flows and their effects on the bearing components as well as the bearing properties during operation. This will provide insights into the stability behavior and load-bearing capacity of GFB.

Teaching

  • Design Against Stress
  • Strength and Fatigue
  • Engineering Design 2
  • Supervised term papers, projects, and bachelor’s and master’s theses

Dipl.-Ing. René Kamieth

Research associate 12/2016 - 10/2019

Research

Joint project: ECOFLEX-Turbo: 1.3.1B Development of a model for monitoring and efficient control for compressors with integrated gearbox - Part B: Vibrations

Area of research

Wind plants are usually designed for a service life of 20 years. The decisive factor is their stability and thus tower and foundation. To ensure continued operation after 20 years, a method is being developed that allows the loads endured during the previous service life and thus remaining service life of the wind plant to be estimated based on standard operating data of the wind plant as well as load measurements on the tower.

Teaching

  • Supervised term papers, projects, as well as Diplom, bachelor’s and master’s theses

Dr.-Ing. Tomasz Pronobis

Research associate 09/2014 - 09/2019

Teaching

  • Balancing Technique practical tutorial
  • Rotor Dynamics practical tutorial
  • Design Theory 2 & 3 practical tutorials
  • Supervised term papers, projects, and bachelor’s and master’s theses

Completed projects:

  • Load detection on ball bearings in aero engines
  • Validation of a Fluid/Solid Heat Transfer Coupling Method for an Aero Engine High
    Pressure Turbine Interstage Cavity
  • Geometrical Optimization, Mechanical Design and Prototype Testing of a Radio Frequency Finger Component connecting Storage Ring Segments in a Synchrotron Type Particle Accelerator
  • Experimental investigation of the influence of a rotor’s design properties on the imbalance correction on a plane

Research

Gas foil bearings (GFBs) are innovative machine elements used to support high-speed rotors without contact on an aerodynamic air film. In this thin air film, sufficiently high pressures are generated at corresponding speeds to support the rotor. The advantages of no lubrication, the possibility of very high speeds, robust temperature behavior and a long service life make the use of GFBs particularly interesting for turbomachines.

Within the scope of the research work, the axial design of these bearings is investigated numerically and experimentally with regard to their vibration behavior. This includes the production of axial gas foil bearings at the academic chair, the model development and numerical solution of the descriptive differential equations as well as the design, execution and evaluation of corresponding test series. Furthermore, the vibrations of complete (axial and radial) air-bearing rotors are predicted numerically and determined experimentally.

Dr.-Ing. Gervais Cèdric Djoko Kayo

Research associate 07/2016 - 06/2019

Area of research

DFG project

Experimental investigation of the dynamic behavior of gas foil bearings and their constructive influenceability

Motivation:

The desire to increase efficiency and power density in turbomachinery can often be achieved by increasing the speed of the rotor. Consequently, the variety of bearing types considered for this purpose is decreasing and the influence of the bearing arrangement, in particular on the vibration behavior, is increasing. Due to the low viscosity of their lubricant, gas foil bearings (GFBs) are suitable for realizing this speed increase for smaller and lighter turbomachinery. In addition to the feasibility of improved efficiencies, the use of gas bearings makes it possible to eliminate the need for a conventional lubrication system and thus reduce the weight and improve the reliability and ease of maintenance of the machine.

Objective:

A major obstacle to the industrial applicability of this bearing type is the reliable prediction of the operating range as well as its increase. The research project aims to provide a significantly improved prediction of the operating range as well as investigate measures to increase the stable operating range.

Dr.-Ing. Christian Gorges

Doctoral candidate from 2015 to 2018, BMW Group

Research

Identifying customer usage profiles of two-wheeled vehicles

Area of research

Virtualization of the usage profiles of motorcycles

 

Dr.-Ing. Robert Hoffmann

Research associate 05/2012 - 04/2017

Area of research

Rotor and machine dynamics

  • Stability analysis of gas foil bearings

Gas-foil bearings are an innovative machine element which are particularly suitable for turbomachine applications such as turbochargers, turbo-compressors or cryogenic pumps due to the advantages of no oil lubrication, high temperature resistance and long service life.

Within the scope of this research, the effects of such bearings on the rotordynamic behavior were investigated numerically and experimentally.

Other areas of work

  • Squeeze oil damper
  • Examination of the behavior of turbochargers

Teaching


Rotor Dynamics

Strength and Fatigue

Supervised term papers, projects, as well as Diplom, bachelor’s and master’s theses

Dr.-Ing. Robert Fay

Research associate 02/2013 - 01/2016

Areas of research

Despite the small direct effect on the dynamics, the gentle rubbing of a rotor can lead to the instability of the rotor, where the rotor deforms in the direction of the non-symmetrical heat input. In order to better predict this effect, named after Newkirk, a test rig is planned at the academic chair.

Sub-area

Numerical simulation of rotor behavior during soft rubbing against brush seals, taking into account the thermal deformation of the rotor to predict stability

Dipl.-Ing. Daniel Kreuzer

Research associate 07/2009 - 10/2016
(associate in the research project 02/2013 - 10/2016)

 

Teaching

  • Supervised term papers, projects, as well as Diplom, bachelor’s and master’s theses
  • Drive Systems and Components practical tutorials

Area of research

Despite the small direct effect on the dynamics, the gentle rubbing of a rotor can lead to the instability of the rotor, where the rotor deforms in the direction of the non-symmetrical heat input. In order to better predict this effect, named after Newkirk, a test rig is planned at the academic chair.

Sub-area

Design and commissioning of a test rig for the experimental investigation of the thermoelastic behavior of high-speed rotors when rubbing against brush seals

Dr.-Ing. Daniel Pucknat

Research associate 12/2008 - 08/2014

Area of research

Product reliability

  • Development of a calculation and evaluation strategy for analyzing the damage tolerance of complex structures.

 

Complex structures have the advantage over simple structures that they can tolerate damage under certain circumstances. Other load paths are activated, resulting in redistribution of the stresses. Such a structure therefore exhibits support effects that can be exploited. Complete freedom from damage is therefore not necessary, provided that the service life that can be determined satisfies requirements, whereby massive weight savings are possible in complex structures. A simulation-based illustration is complex, as in addition to the usual fatigue strength verification, a fracture mechanics evaluation must be performed to determine an overall service life. Within this research project, a calculation and evaluation strategy has been developed, which allows such a component evaluation with common tools. The basis is a new transparent strength hypothesis, which is specifically based on the application and needs of FEM/ BEM calculations.

Zeise

Dr.-Ing. Bärbel Zeise

Research associate 10/2010 - 05/2014

Research

Product reliability

  • Simulation of friction corrosion
  • Strength calculations of friction fatigue fractions

 

The primary objective of this research is the strength assessment of joints under friction corrosion with regard to the prediction of a fracture-inducing crack. In fundamental contrast to the prevailing approach, the wear-induced change in contact configuration is simulated beforehand separately from the failure assessment.

Dr.-Ing. Henrike Kuntz (née Nimmig)

Research associate 01/2008 - 12/2012

 

Teaching

  • Drive Systems and Components I practical tutorial
  • Drive Systems and Components II practical tutorial (simulation)
  • Rotor Dynamics practical tutorial
  • Design Theory 2 practical tutorial
  • Supervised term papers, projects, as well as Diplom, bachelor’s and master’s theses

Other work

  • Course guidance for the Design Engineering and Mechanical Engineering degree programs
  • Research in the field of Gender Diversity

Areas of research

  • Active vibration reduction in aero engines with Piezo actuators

Piezo actuators are used as vibration-reducing elements in numerous products.  However, their use in aircraft engines presents a particular challenge due to the boundary conditions. The behavior of piezo actuators under consideration of these boundary conditions and the installation space was investigated analytically and experimentally in more detail within the scope of this research project.

Industry projects

  • Siemens: Balancing theory

Dr.-Ing. Piotr Kalinowski

Research associate 06/2007 - 05/2012

Areas of research

Rotor dynamics

  • Core-Blade-Off Events
  • Modal analysis
  • Examination of the behavior of turbochargers and squeeze oil damper assembly

Dr.-Ing. Andreas Scholz

Research associate 02/2008 - 01/2011

 

Areas of research

  • Rotor dynamics
  • Passive damping systems in aircraft engines
  • Modeling of the frequency and temperature-dependent behavior of viscoelastic materials

Projects

  • Qualified Elastomerrings for Engine Rotor Damping (EU-project FP7) Industrial partner: Rolls-Royce Deutschland

This EU-funded research project investigated the suitability of elastomer rings for reducing engine vibrations. These passive vibration dampers offer a significant cost advantage over conventional squeeze oil dampers.
However, the thermal conditions in the area of the engine bearings pose an extreme challenge for elastomers. The search for suitable materials is therefore a major component of this work.
To investigate the damping effect of the elastomer rings, a component and a rotor test rig were developed at our academic chair.
The analysis of the overall engine structure was carried out in cooperation with Rolls Royce.
 

  • Siemens: Friction coefficient determination of electrical sheets

Dr.-Ing. Torsten Sadowski

Research associate 05/2004 - 05/2009

Areas of research

  • Simulation of dynamic systems

Other work

  • System administration

Dr.-Ing. Jules Bertrand Njinkeu

Research associate 11/2003 - 10/2008

Areas of research

  • Reliability of mechanical building elements
  • Design against stress
  • Failure mechanisms of metallic components

Fields of specialization

  • Friction corrosion
  • Wear simulation

Dipl.-Ing. Boris Gieseler

Research associate 10/2003 - 09/2008

 

Areas of research

  • Elastomer couplings
  • Design against stress

Fields of specialization

  • Programming of finite elements
  • Examination of material laws

Dr.-Ing. Benjamin Kloss-Groe

ehem. Wissenschaftlicher Mitarbeiter

 

Areas of research

  • Design against stress
  • Mechanical integrity and functionality of steam turbines (static stress, creeping, LCF, HCF, ...)
  • Dynamic device behavior of washing machines
  • Design project risk management

 

Dipl.-Ing. Oliver Capek

Research associate 04/2003 - 03/2008