Accuracy enhancement of fatigue damage counting using design sensitivity analysis

• The design sensitivity index is proportional to the response energy.
• The accuracy of the damage counting method is enhanced with design sensitivity analysis.
• The new counting method is optimally robust against unexpected noise in the output data.
• Simulation and testing of uniaxial excitation prove the accuracy of the predicted damage.

Recent studies have suggested fatigue damage counting of a linear elastic system using only the output data; design sensitivity analysis based on the transmissibility function was studied in order to identify the most sensitive response location under intact conditions. The design sensitivity index was derived to be proportional to the response energy at the measured point through reformulation of the previous equation for the sensitivity index. The accuracy of the damage counting method can be enhanced with design sensitivity analysis by selecting the location with the maximum response energy; the method is optimally robust against unexpected noise in the output data. Simulation and testing of a notched simple specimen under uniaxial excitation were used to verify that sensitivity analysis enhances the accuracy of the predicted damage counting.