Mechanics, Friction & Noise
When designing frictionally engaged component joints, such as flange and screw connections for example, precise knowledge of the friction coefficient plays an important role. In addition, torque transmission can be ensured with the help of higher static friction values, which in turn reduces the number of connecting elements and their dimensions. In this project, static friction values were calculated on standardised test stands and geometric parameters derived. The share of friction mechanisms and the friction characteristics of frictionally engaged surface pairings could be shown separately for the first time through simulation. Investigations of PVD (Physical Vapour Deposition) coatings, thermal sprayed coatings and laser structures show that it is possible to significantly increase friction co-efficiency with all three methods. Thus the user has different variations at his disposal, which can be selected based on application-specific criteria. With the project results, the user is capable of designing frictionally engaged component connections with greater resource efficiency in the future.
» With the results of the GECKO cluster project, we have increased our understanding of static friction significantly. The success rests especially on the excellent collaboration between the five scientific institutions and the members of the project user committee. «
With their phenomenal adhesive power on smooth, vertical surfaces, geckos are a favorite object of bionic fans: for many years research has been investigating and describing the microstructure of gecko surfaces and the physics that make their impressive surface adhesion possible.
Friction-enhancing hard coatings | Thin and thick coatings for friction-optimised surfaces: Grid electron microscopy of a friction-enhancing ta-C layer.
Determination of static friction coefficient on model test stands: Standardised static friction test stand.
Using the project results it is possible to design elements for friction power transfer, such as flange joints for example, in an improved and more resource-efficient manner.
Frictionally engaged component joints, such as flange and screw connections for example, are present in many applications. Precise knowledge of their friction coefficient is essential for dimensioning. In addition, torque transmission can be ensured with the help of higher static friction values, which in turn reduces the number of connecting elements and their dimensions. Which parameters influence static friction and how static friction values can be increased through laser structuring and coatings were the questions this project focused on.
The experimental static friction appraisal on standardised test stands formed the starting point. This was followed by the development of geometric parameters, which correlated with the static friction values. Using a newly developed 3D FEM Contact and Friction model for coarse surfaces, the simulation was conducted. It served especially to determine the share of active friction mechanism deformation and adhesion. The investigation of friction enhancing PVD coatings and laser structures was a further focus.
With the results it is possible to design frictionally engaged connections with greater resource efficiency in the future. The user has at his disposal a large number of static friction values, friction characteristics as well as valuable insights into the design of frictionally engaged surfaces. Furthermore, the test stands and the standardised test methods could be used for determining individual friction coefficient certifications. Using simulations it was possible to show the share of friction mechanisms and the friction characteristics for friction surface pairings separately. The newly developed friction enhancing coating system and laser structuring offers the user great potential for maximising static friction values. There are different variations available, which can be selected based on the specific application.
GECKO (Cluster) | Design and identification of characteristic data of friction contact optimised surfaces
Sub-project I | Characteristic data analysis and synthesis | Project No. 1075 | AiF Funding ID 17228 BR
Sub-project II | Metrological description of the geometric properties of frictionally engaged surfaces | Project No. M3408 | DFG Funding ID DI 617/27-1
Sub-project III | Simulation of friction grip | Project No. M3408 | DFG Funding ID DE 582/13-1
Sub-project IV | Friction-hard coatings | Project No. 1076 | AiF Funding ID 17230 BR
Sub-project V | Friction-laser structuring | Project No. 1077 | AiF Funding ID 17229 BR
2011-07-01 to 2014-06-30
Dr.-Ing. Anton Stich
Overall Coordination of the Cluster Project:
Prof. Dr.-Ing. Erhard Leidich
SP I | Institute of Construction and Drive Technology (IKAT) | Chair of Engineering Design |TU Chemnitz
Head of research:
Prof. Dr.-Ing. Erhard Leidich
Matthias Gräfensteiner, M. Eng.
SP II | Institute of Production Metrology and Quality Assurance (IFMQ) | TU Chemnitz
Dr.-Ing. Marko Gerlach
Dipl.-Ing. Saskia Schiefer
SP III | Institute of Machine Design (IMK) | Chair of Machine Elements and Tribology (LMT) | Otto-von-Guericke University Magdeburg (OVGU)
Head of research:
Prof. Dr.-Ing. habil. Dirk Bartel
Dipl.-Ing. Andreas Kießling
SP IV | Fraunhofer-Institute of Material and Beam Technology (IWS)
Dr.-Ing. Otmar Zimmer
Dr. Volker Weihnacht
SP V | Laser Institute – University of Applied Sciences Mittweida (LHM)
Dr. Jörg Schille
Research & Technology Performers
Research Association for Combustion Engines eV
Lyoner Strasse 18
60528 Frankfurt am Main
T +49 69 6603 1345