Investigations on the influence of cold-forming and associated residual stresses on the fatigue strength of thin-walled details

A code for the design of cold-formed thin-walled structures in accordance with fatigue requirements currently does not exist in Europe. Part 1993-1-3 of the Eurocode [1] only standardizes the static design. In part 1993-1-9 [2] for design and construction under fatigue loads cold-formed thin-walled profiles are explicitly excluded. Corresponding elements have, however, become established in the construction of racking systems, as they represent an efficient and economical way of creating storage capacities. In contrast to the former use of storage systems, manual retrieval and storage (S/R), increasing automation through S/R-machines leads to cyclical loads in uprights and struts. In addition to purely static loads, this results in a dynamic component that cannot be neglected. Experimental investigations, such as monotonic and cyclic tensile tests, are used to determine changes in material properties after cold-forming by bending. Special focus is put on the influence of bending radii in combination with the thickness on the plastic deformation and associated internal residual stresses. These parameters can have a significant impact on the fatigue behavior. The aim of the tests with a new invented testing device is to provide a basis for the development of adequate fatigue design rules for storage systems