@article{YanagimotoOyaKawanishietal., author = {Yanagimoto, Jun and Oya, Tetsuo and Kawanishi, Seiichiro and Tiesler, Nicolas and Koseki, Toshihiko}, title = {Enhancement of bending formability of brittle sheet metal in multilayer metallic sheets}, series = {CIRP Annals}, volume = {59}, journal = {CIRP Annals}, number = {1}, doi = {10.1016/j.cirp.2010.03.109}, pages = {287 -- 290}, abstract = {The formability of multilayer metallic sheets is evaluated by tensile, V-bending, hat bending and hemming tests. A monolithic type-420J2 stainless steel sheet cannot be formed because of poor elongation as small as 1.7\%. Marked enhancement of the bending formability was observed in the bending of type-420J2 stainless steel sheets when they are layered by type-304 stainless steel sheets and composed into a multilayer metallic sheet. The mechanism of the enhancement of the formability of type-420J2 stainless steel in a multilayer metallic sheet is investigated analytically by focusing on the delay of the initiation of necking, and by performing stress analysis by finite element method (FEM).}, language = {en} } @article{OyaTieslerKawanishietal., author = {Oya, Tetsuo and Tiesler, Nicolas and Kawanishi, Seiichiro and Yanagimoto, Jun and Koseki, Toshihiko}, title = {Experimental and numerical analysis of multilayered steel sheets upon bending}, series = {Journal of Materials Processing Technology}, volume = {210}, journal = {Journal of Materials Processing Technology}, number = {14}, doi = {10.1016/j.jmatprotec.2010.07.003}, pages = {1926 -- 1933}, abstract = {In this study, the bending formability of multilayered steel sheets is evaluated by tensile tests, V-bending tests, and hemming tests. Enhanced formability was observed in these experiments, namely, the constituent high-strength materials were elongated beyond the original fracture strain limit. As a result of this effect, multilayered steel sheets were successfully formed in V-bending tests and even in hemming tests. Observations using a scanning electron microscope verified that no delamination occurred at interfaces. To represent the geometrical features of a multilayered steel sheet, a solid-element model under an isostrain condition was utilized in finite element modeling, where the rule of mixtures was adopted to obtain the flow curve of the constituent high-strength material, and a good agreement with experimental results was observed. Analyses using this finite element model were conducted to investigate the effect of the geometry on the springback of multilayered steel sheets undergoing V-bending.}, language = {en} } @inproceedings{Tiesler, author = {Tiesler, Nicolas}, title = {Prozessentwicklung f{\"u}r das Laserstrahlschweissen in der modernen Großserie}, series = {Laserbearbeitung in der Feinwerk- und Mikrotechnik der Reihe "Aachener Laserseminare"}, booktitle = {Laserbearbeitung in der Feinwerk- und Mikrotechnik der Reihe "Aachener Laserseminare"}, language = {de} } @inproceedings{TieslerPletzenauer, author = {Tiesler, Nicolas and Pletzenauer, Clemens}, title = {Anforderungen der modernen Großserie an das Laserschweissen}, series = {Laser in der Elektronikproduktion \& Feinwerktechnik - Tagungsband der LEF 2005}, booktitle = {Laser in der Elektronikproduktion \& Feinwerktechnik - Tagungsband der LEF 2005}, publisher = {Meisenbach Verlag}, address = {Bamberg}, pages = {131 -- 143}, language = {de} } @article{TieslerGeigerEngel, author = {Tiesler, Nicolas and Geiger, Manuel and Engel, Ulf}, title = {Cold Forging of Microparts}, series = {Production Engineering X(1)}, journal = {Production Engineering X(1)}, language = {en} } @article{Tiesler, author = {Tiesler, Nicolas}, title = {Microforming-size effects in friction and their influence on extrusion processes}, series = {Wire}, volume = {52}, journal = {Wire}, number = {1}, pages = {34 -- 38}, abstract = {When scaling down a forming process from conventional to micro forming, size effects occur. This paper presents the effect of miniaturization on friction in bulk metal forming, investigated with the Double Cup Extrusion test. The experimental results show an increase in friction with decreasing specimen size when using extrusion oil as lubricant. The amount of changes in friction conditions was determined by a numerical identification with FE-simulation. To explain the observed effects a model has been developed, which is based on the theory of open and closed lubricant pockets. The model could be verified by additional, independent experiments and also by surface measurements. The consequences of the frictional size effects for the design of microforming processes have been shown in full forward and combined full forward cup backward extrusion experiments. In addition, an increasing influence of the grain size can be observed with miniaturization.}, language = {en} } @phdthesis{Tiesler, author = {Tiesler, Nicolas}, title = {Grundlegende Untersuchungen zum Fließpressen metallischer Kleinstteile}, series = {Fertigungstechnik - Erlangen}, journal = {Fertigungstechnik - Erlangen}, editor = {Geiger, Manfred and Feldmann, Klaus}, publisher = {Meisenbach Verlag}, address = {Bamberg}, isbn = {3-87525-175-X}, issn = {1431-6226}, doi = {10.25593/3-87525-175-X}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:29-opus4-130736}, pages = {126}, abstract = {Diese Arbeit befasst sich mit dem Fließpressen metallischer Kleinstteile, wobei insbesondere auf die bei der Miniaturisierung auftretenden Gr{\"o}ßeneffekte eingegangen wird. Einen wesentlichen Schwerpunkt bilden grundlegende Untersuchungen zu Miniaturisierungseffekten bei der Reibung und deren Auswirkungen auf die erforderlichen Prozesskr{\"a}fte und die Formausbildung. Des weiteren wird der Einfluss der Mikrostruktur auf den Prozess untersucht.}, language = {de} } @inproceedings{TieslerEngelGeiger, author = {Tiesler, Nicolas and Engel, Ulf and Geiger, Manuel}, title = {Basic research on cold forging of microparts}, series = {Proceedings of the 7th ICTP, 2002}, booktitle = {Proceedings of the 7th ICTP, 2002}, language = {en} } @article{GeigerKleinerEcksteinetal., author = {Geiger, Manuel and Kleiner, Matthias and Eckstein, R. and Tiesler, Nicolas and Engel, Ulf}, title = {Microforming}, series = {CIRP Annals}, volume = {50}, journal = {CIRP Annals}, number = {2}, doi = {10.1016/S0007-8506(07)62991-6}, pages = {445 -- 462}, abstract = {Microforming is a well suited technology to manufacture very small metallic parts, in particular for mass production, as they are required in many industrial products resulting from microtechnology. Compared to other manufacturing technologies microforming features specific economical and ecological advantages. Nevertheless, there are only some singular applications known until today. This paper tries to find out the reason why, analyzing systematically the problems emerging in transferring the know-how on forming from the macro- to the microworld. Reviewing the state of the art in basic and applied research reveals that scaling effects do appear not only within the process but must be taken into account in all the other areas of the whole forming system as well, demanding finally new solutions especially for tool manufacturing and machine concepts. Recent progress, innovative ideas and new developments on these sectors represent a promising basis to exploit the inherent potential of microforming in the future.}, language = {en} } @article{TieslerEngel, author = {Tiesler, Nicolas and Engel, Ulf}, title = {Microforming-effects of miniaturization}, series = {Proceedings Metalforming}, journal = {Proceedings Metalforming}, pages = {355 -- 360}, language = {en} } @inproceedings{Tiesler, author = {Tiesler, Nicolas}, title = {Forming of microparts-effects of miniaturization on friction}, series = {Advanced Technology of plasticity, Proceedings of the 6th International Conference on Technology of plasticity}, booktitle = {Advanced Technology of plasticity, Proceedings of the 6th International Conference on Technology of plasticity}, publisher = {Springer}, pages = {889 -- 894}, language = {en} } @inproceedings{EngelTieslerEckstein, author = {Engel, Ulf and Tiesler, Nicolas and Eckstein, Ralf}, title = {Microparts - a challenge for forming technology}, series = {Conference Proceedings ICIT 2001 3rd International Conference on Industrial Tools}, booktitle = {Conference Proceedings ICIT 2001 3rd International Conference on Industrial Tools}, editor = {Kuzman, K.}, pages = {31 -- 39}, language = {en} }