Influence of structural damages on first passage time maps

Current damage detection methods usually rely on changes in modal properties. Another approach, based on the mathematical concept of First Passage Time (FPT), is considered here. The FPT is defined as the time required for a signal to reach a target level Xf , starting from a level X0. This information can be computed, through a suited algorithm for various combinations of X0 and Xf at once, as maps of any statistical moment of FPT and even as Probability Density Functions (PDFs) of FPT. In this paper, by comparing a reference case and three damaged cases of a simple structure, it has been observed and validated that the PDFs of FPT are significantly different while the natural frequencies show no or slight difference. Therefore, the FPT can capture slight structural behavioral changes and then becomes a promising useful tool for early damage detection.