Research on multiaxial fatigue life prediction of lifting equipment based on symbol corrected equivalent stress spectrum

During the cyclic operation of lifting equipment, critical structural fatigue damage and fracture failure often occur, causing huge economic losses and even leading to major accidents. In practical work, lifting equipment not only bears tensile and compressive loads but also significant shear loads. Under its actual working conditions, it causes multiaxial fatigue damage. This article studies the multiaxial load spectrum obtained by deploying fiber Bragg gratings strain rosette in high-risk and prone-to-cracking areas of lifting equipment and using a multiaxial stress equivalent method based on symbol correction, the multiaxial complex stress spectrum is equivalent to a modified uniaxial stress spectrum. Combined with the developed dual parameter four peak valley rain flow fast counting algorithm program, the cumulative damage caused is calculated using the Miner linear cumulative fatigue damage model. Finally, a prediction is made for the multiaxial load fatigue life of high-risk and prone-to-cracking areas in lifting equipment. The results show that the multiaxial fatigue life prediction method for high-risk and prone-to-cracking areas of lifting equipment based on symbol corrected Von Mises equivalent stress spectrum in this article is more accurate than the prediction results obtained from classical Von Mises equivalent stress spectrum and uniaxial stress spectrum calculations, which to some extent solves the problem of difficult engineering application of current multiaxial fatigue theory.