The multiple-incremental hole drilling method

Up to now the measurement uncertainties of residual stress determinations using the incremental hole-drilling-method had to be assessed by repeating the measurement at equivalent measurement spots or specimens. Often, the requirements for those repetitions are not given or the effort is spared. The determination of the stress state plus the related measurement uncertainty by only one course of measurement is the main feature of the Multiple-Incremental Hole Drilling Method developed by the Fraunhofer Institute for Mechanics of Materials IWM. The method is based on the generation and processing of multiple strain recordings for each depth increment through a stepwise enlargement of the hole in lateral direction. The results show that the new method allows revealing and quantifying measureme nt uncertainties of the determined stress-depth profile.