Joint Research Project QuInLas

Sub-Project:

Quality effects on the fatigue strength of laser- and laserhybrid welded ship structures

Field of Research: Fatigue Strength; Fabrication Effects on Structural Behaviour

Duration: 1st Dec. 2009 – 30th Nov. 2012 extended to 30th Nov.2013

Project Leader: Prof. Dr.-Ing. W. Fricke

Sponsorship: BMWi (FKZ 03SX271B) – 10 Partners (Coordination iLAS/TUHH)

Website: http://www.tuhh.de/quinlas.html

Abstract

In this partial project of QuInLas, experimental and numerical investigations on laser and laser-hybrid welded joints and structures with respect to applications in shipbuilding were performed, new structural design concepts were developed and the basis for an integrated quality assessment was laid in cooperation with LBF Darmstadt (Fraunhofer Institute of Structural Durability and System Reliability). In this way the partial project supports the main objective to improve the ship structure by innovation on the basis of new joining technologies with the laser technique and to increase the productivity.

Within the QuInLas-project our institute and the Fraunhofer LBF were involved in processing of Wöhler and Gassner fatigue tests of over 50 different specimen-types which were investigating the fatigue strength of laser- and laser-hybrid welded constructions. The tests included conventionally manufactured joints like butt joints, cruciform or T-joints which are very common in ship-structures, as well as innovative joints which are optimized on being manufactured with laser-welding robots. Picture 1 shows an overview of the projected fatigue-tests . Green-colored specimens are conventionelly while white colored are innovatively manufactured specimens.

Picture 1: Overview of fatigue tests

The QuInLas-project aimed to find correlation between quality assessment and fatigue strength. For that the investigated welds were messured by a laser-scanner and were modelled for a finite element analysis to find the geometric parameters which effect the fatigue strength. The Notch-stress-concept was applied. Some examples of these notch-stress-modells and the polished microcraph sections is mapped in picture 2.

Picture 2: polished micrograph sections and notch stress modells of a both-sided laser welded, a both-sided laser-hybrid welded and an one-sided laser-hybrid welded transverse stiffener

 

For further information see the listed publications and the final report.

Publications:

  • Emmelmann, C.; Kirchhoff, M.; Fricke, W.; Robert, C.; Drenker, A.; Niese, F.; Wagener, R.; Kogel-Hollacher, M.; Paul, C. und Thieme, J.: Innovative Schiffsfertigung durch dreidimensionales Laserstrahlschweißen – Forschungs­vorhaben QuInLas. In: Schweißen im Schiffbau und Ingenieurbau 2011, p. 68-73, DVS-Berichte Band 277, DVS Media, Düsseldorf 2011
  • Emmelmann, C.; Kirchhoff, M.; Fricke, W.; Robert, C.; Drenker, A.; Niese, F.; Wagener, R.; Kogel-Hollacher, M.; Paul, C.; Thieme, J.; Westphäling, T.: QuInLas – Qualitätsgerechte 3D Laser-Schweißbearbeitung innovativer Schiffskonstruktionen; Statustagung Schifffahrt und Meerestechnik, Tagungsband der Statustagung 2012, S.133-146; Schriftenreihe Projektträger Jülich; publisher: Forschungszentrum Jülich GmbH Zentralbibliothek, Jülich, ISBN 978-3-89336-832-7 ; Jülich December 2012
  • Fricke, W.; Robert, C.: Quality effects on the fatigue strength of laser- and laserhybrid welded ship structures – Final report of sub-project of BMWi R&D-joint research project QuInLas 03 SX 271 (in german); publisher: Schriftenreihe Schiffbau, Hamburg University of Technology, ISBN 978-3-89220-677-4 , May 2014
  • Robert, C.; Fricke, W.: Assessment of quality effects on the fatigue life of laser and laser-hybrid welded specimens, IIW-Doc. XIII-2542-14, International Institute of Welding, July 2014
  • Fricke, W.; Robert, C.: Bewertung von Einflüssen der Schweißnahtqualität auf die Schwingfestigkeit von laserstrahl- und laserstrahl-MSG-hybridgeschweißten Quersteifen, Schweißen und Schneiden 67, p. 106-113, April 2015

Persons:

Prof. Dr.-Ing. W. Fricke

Dipl.-Ing. Christoph Robert

Dipl.-Ing. Matthias Guiard