A dual-sensing method for fracture prediction of mechanical structures under variable loads

Due to the inherent uncertainties caused by the manufacturing process variation, future loading conditions and damage models, the time to failure of the mechanical structures under field stress condition is substantially different from the result in laboratories. For the purpose of efficient maintenance or preventing casualties, it is substantially useful to prognosticate the failure in advance of target structure failure although the absolute time to failure cannot be predicted. In this paper, the embedded structure, which is a slightly weaker structure designed to produce failure earlier than the target structure, were developed and monitored with strain gauges. The strain difference between two embedded structures was used as a warning signal in advance of the target structure failure. The strain difference according to variable loads was successfully featured and clustered clearly for differentiating normal status and warning status, i.e. the failure of the embedded warning structure.