Mechanical Reliability

Fatigue design of laser beam welded joints under multiaxial stress (LaserMultiAx)


Welded joints are subject to multi-axial loads in almost all applications.Nowadays, such joints in the automotive area are usually designed on the basis of empirical design criteria, because the required design parameters for multi-axially stressed welds are not sufficiently available for materials that are difficult to weld. However, reliable data on the stressability of laser beam welded joints subject to cyclical multi-axial stress are necessary in order to increase component safety and to develop further lightweight construction potential on the one hand and to drastically reduce design and development times on the other.


The aim of the project is the development of specifications for load- and process-oriented designs for laser-welded drive components, taking into account weld defects, residual weld stresses, complex 3D stress states in the seam and the local stressability of the weld seam areas. The objective is to increase component safety and to better exploit the potential of lightweight construction.


Based on the analysis of representative components, the typical seam stresses are classified and the basic concept for the specimen geometry and test loads is derived from this. Subsequently, the test specimens are designed and manufactured using state-of-the-art laser beam welding technology. The main focus of the work will be the cyclical multi-axial testing of the specimens with variation of the load components. The evaluation of the fatigue strength will then be carried out using local concepts, with the aim of developing a generalisable methodology for the evaluation of multi-axial stress states in laser beam welded rotationally symmetrical components.

Information about the project

Research facilities:

  • Fraunhofer Institute for Material and Beam Technology IWS
  • Technical University Darmstadt, Research group System Reliability, Adaptive Structures, and Machine Acoustics (SAM)

AiF- Project, IGF 20.621
DVS – German Welding Society
Duration: 30 months, 01.04.2019 to 30.09.2021


M.Sc. Markus Faß
Tel: 06151 705-474