Analysis and Reconstruction of Helicopter Load Spectra

Helicopter load histories applied to notched metal samples are taken as examples, and their fatigue lives are predicted by using a simplified version of the localstrain appraoch. A peak-valley reconstructed history is generated based on the standard spectrum Helix. A second history studied is a more irregular one based on actual flight data. It is used to generate three reconstructed histories based on three principles: peak-valley, to-from, and rainflow. Life predictions are presented for all the above cases, and the comparison with test data and other considerations suggest that the most promising reconstruction approach is one based on rain-flow cycle counting.