Fatigue

Metal fatigue is one of the most common and costly failure types. It begins by initiation of microcracks, typically in areas of high stress and subsequently evolves into macroscopic crack growth.  

At the moment, prediction of the life of any component within a factor 10 of the actual life must be considered good. This is how well it can be done. It is however not satisfactory, neither in a scientific nor in an engineering context. Too many components are designed to be much too bulky to stay on the safe side.

The main focus of this group is therefore to improve the understanding of the causes and processes in fatigue and developing better prediction methods.

Weld quality and fatigue

The current quality code for welded joints, ISO 5817, was not developed for fatigue applications, but rather defines the quality in terms of "good workmanship". Major efforts are therefore directed towards development of a replacement system which is consistent in terms of fatigue. It is commonly agreed that the dominating feature is the sharpness of the weld toe, as illustrated below - the smoother the better.

Fatlab project

Fatlab is a free open source fatigue analysis software developed in Matlab. Fatlab works by postprocessing results from FE analyses and combining these with load-time series in order to perform a detailed fatigue assessment of a component. It handles both multiaxiality (through the critical plane method) and non-linear FE models.

Crack propagation analysis

An ongoing project is aimed at developing a self-contained crack propagation analysis software for predicting remaining life in cracked components using numerical fracture mechanics. At its current state, the software relies on the VCCT approach in combination with the nodal release technique.

Group members

Research Topics

  • Fatigue in machined components, welded joints and steel structures
  • Factors affecting fatigue strength, e.g. surface, material, environment, etc.
  • Fatigue in 3D printed metal components
  • Multiaxial fatigue
  • Variable amplitude loading
  • Crack propagation analysis
  • Fracture mechanics
  • Finite element analysis