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Peters R.,SLV Mecklenburg Vorpommern GmbH | Sumpf A.,SLV Mecklenburg Vorpommern GmbH | Ungermann D.,TU Dortmund | Russe C.,TU Dortmund | And 2 more authors.
Stahlbau | Year: 2015

Laser-stake welding enables an economic production of all-steel sandwich panels that can be used for steel bridges as well as for decks in ro/ro ships. Deck plates of 10 mm thickness can be joined to interior web plates ensuring a weld throat thickness of 2 to 3 mm. Up to now the thickness of cover plates which could be stake welded in acceptable quality was limited to 4 mm. For this reason these sandwich panels could be used only for secondary structures in shipbuilding or similar only static strained structures. In the frame of FOSTA project P869 "Laser beam welded T-joints" (IGF 16935 BG) reliable welding parameter and technologies were developed to join cover plates up to 10 mm thickness to enable the use of sandwich panels in higher strained, fatigue loaded structures. Fatigue tests were performed with laser-stake welds subjected to axial, shear and multiaxial in-phase loading and assessed by the nominal and the notch stress approach. In addition to possible effects of gaps between deck and web plates or of the steel strength, the application of interaction formulae to laser-stake welds is checked as contained in Eurocode 3 and the IIW recommendations for the fatigue assessment of multiaxial loading. In this way, the basis is provided for a safe design of laser-stake welded T-joints. A technology for tractor-based assembly of these panels using laser beam and laser beam GMA welding was developed simultaneously. © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source


Bonk S.M.,University of Rostock | Oldorf P.,SLV Mecklenburg Vorpommern GmbH | Peters R.,SLV Mecklenburg Vorpommern GmbH | Baumann W.,University of Rostock | Gimsa J.,University of Rostock
Micromachines | Year: 2015

We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO) plating or were prepared from platinum sputtering (100 nm) onto a 10-nm titanium adhesion layer. Direct processing of the sensor structures (approximately three minutes per chip) by an ultrashort pulse laser facilitated the production of the prototypes. pH-sensitive areas were produced by the sputtering of 60-nm Si3N4 through a simple mask made from a circuit board material. The system body and polydimethylsiloxane (PDMS) molding forms for the microfluidic structures were manufactured by micromilling using a printed circuit board (PCB) milling machine for circuit boards. The microfluidic structure was finally imprinted in PDMS. Our approach avoided the use of photolithographic techniques and enabled fast and cost-efficient prototyping of the systems. Alternatively, the direct production of metallic, ceramic or polymeric molding tools was tested. The use of ultrashort pulse lasers improved the precision of the structures and avoided any contact of the final structures with toxic chemicals and possible adverse effects for the cell culture in lab-on-a-chip systems. © 2015 by the authors. Source


Fricke W.,TU Hamburg - Harburg | Robert C.,TU Hamburg - Harburg | Peters R.,SLV Mecklenburg Vorpommern GmbH | Sumpf A.,SLV Mecklenburg Vorpommern GmbH
Welding in the World | Year: 2016

Laser-stake welding enables an economic production of all-steel sandwich panels that can be used for steel bridges as well as for decks in roll-on/roll-off ships (ferries). Deck plates of 10 mm thickness can be joined with interior web plates ensuring a weld throat thickness of 2–3 mm. In a research project, fatigue tests were performed with laser-stake welds subjected to axial, shear and multiaxial in-phase loading and assessed by the nominal and the notch stress approach. In addition to possible effects of gaps between deck and web plates or of the steel strength, the application of interaction formulae to laser-stake welds is checked as contained in Eurocode 3 and the IIW recommendations for the fatigue assessment of multiaxial loading. Furthermore, the equivalent von Mises stress is applied using the notch stress approach. In this way, the basis is provided for a safe design of laser-stake-welded T-joints. © 2016, International Institute of Welding. Source


Oldorf P.,SLV Mecklenburg Vorpommern GmbH | Peters R.,SLV Mecklenburg Vorpommern GmbH | Bonk S.,University of Rostock | Gimsa J.,University of Rostock
Galvanotechnik | Year: 2014

Due to their outstanding properties ultra-short pulsed lasers (USP) have recently gained strong interest in laser material processing. While first applications of this laser type have been mainly found in mass production like photovoltaics or cutting of hardened glass for display panels, nowadays, a broad range of diverse applications e.g. in biomedical, LED- or semiconductor technologies is emerging, making USP-lasers one of the fastest growing fields in laser technology. This article will present results of the USP-microstructuring of nano-coated Lab-on-a-chip devices (LOC's) for biosystems technologies as well as results of the USP-micromachining of glass fiber reinforced and flexible PCB 's made of polyimide. Source


Oldorf P.,SLV Mecklenburg Vorpommern GmbH | Peters R.,SLV Mecklenburg Vorpommern GmbH | Reichel S.,SLV Mecklenburg Vorpommern GmbH | Schulz A.-P.,Universitatsklinikum Schleswig Holstein | Wendlandt R.,Universitatsklinikum Schleswig Holstein
Physics Procedia | Year: 2015

The aim of the project called "EndoLas" is the development of a reproducible and reliable method for a functionalization of articulating surfaces on hip joint endoprostheses due to a reduction of abrasion and wear by the generation of micro structures using ultrashort laser pulses. On the one hand, the microstructures shall ensure the capture of abraded particles, which cause third-body wear and thereby increase aseptic loosening. On the other hand, the structures shall improve or maintain the tribologically important lubricating film. Thereby, the cavities serve as a reservoir for the body's own synovial fluid. The dry friction, which promotes abrasion and is a part of the mixed friction in the joint, shall therefore be reduced. In experimental setups it was shown, that the abrasive wear can be reduced significantly due to micro-structuring the articulating implant surfaces. To shape the fine and deterministic cavities on the surfaces, an ultra-short pulsed laser, which is integrated in a high-precision, 5-axes micro-machining system, was used. The laser system, based on an Yb:YAG thin-disk regenerative amplifier, has an average output power of 50 W at the fundamental wavelength of 1030 nm, a maximum repetition rate of 400 kHz and a pulse duration of 6 ps. Due to this, a maximum pulse energy of 125 μJ is achievable. Furthermore external second and third harmonic generation enables the usage of wavelengths in the green and violet spectral range. © 2015 The Authors. Source

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