HFMI Sequence influence

About the project

The extension of the service life of buildings or the creation of resource-saving constructions are the current challenges of the construction and mechanical engineering industry. For fatigue-stressed welded structures, the applicants were able to show, among other things, that higher-frequency hammering methods (HFH methods) can be successfully used to increase fatigue strength. One reason for the still very restrained use of these methods in practice is currently the objections of the approval authorities regarding their effectiveness under operational stress. This reservation is primarily based on the assumption that the residual compressive stresses generated are reduced during operation and may therefore lose their initial effect. Furthermore, it has not yet been clarified how the effect of such post-treatments can be taken into account in a reliable proof of operational strength.

For this reason, the effectiveness of the higher-frequency hammering processes under operational stress is to be investigated within the framework of this research project. In particular, the influence of the sequence under different load collectives will be analysed and named. The aim is to provide an economic and safe damage accumulation hypothesis for post-treated weld details. Since the effectiveness of the HFH methods is based on internal compressive residual stresses and hardening, extensive investigations are being carried out on the behaviour of these influencing variables under operational stress.