Simulation and analysis method for dynamic fatigue reliability of shovel stick for mining electric shovel

In order to reduce the stick fracture caused by random load during the operation of the electric shovel in open-pit mines, a simulation and analysis method of the dynamic reliability of the stick of the electric shovel in the mining was proposed. Based on the actual size parameters of the mining shovel, the three-dimensional model of the excavation and lifting parts was constructed, and the ADAMS-Matlab/Simulink electromechanical simulation model of the working device was established in combination with the coupling effect of the mechanical system and the electrical system, and the stress curves of the dangerous points of the stick under different working conditions were obtained. The stress data were counted by the rainflow counting method, and the distribution cha racteristics of stress amplitude, mean and peak value were obtained, and the multi-level load characteristic param eters were obtained by stress correction. The Schaff nonlinear theory was used to establish the residual strength model of the shovel stick under multi-stage load, and the strength degradation law of the shovel stick was obtained by combining the global stress-life curve. Based on the stress-strength interference theory, the bending fatigue failure limit state function of the mining power shovel stick was established, the dynamic reliability model of the mining power shovel stick was established, and the time-varying fatigue reliability of the stick under the strength degradation process was calculated by using the method of active learning Kriging and Monte Carlo simulation method (AK-MCS), and the phased maintenance strategy of the stick was proposed. The simulation analysis shows that the attenuation rate of bending fatigue reliability under different working conditions is consistent, which is slow first and then fast, but due to the influence of the residual strength attenuation rate, the attenuation time of the bending fatigue reliability of the stick is earlier and faster under the condition of 100% full bucket rate, and the fatigue failure time of the stick is advanced. The results show that the dynamic fatigue reliability simulation analysis method of mining electric shovel stick can obtain the stress characteristics of dangerous points and time-varying fatigue reliability of mining electric shovel stick under complex working conditions, which provides a basis for the reliability design and maintenance of mining electric shovel stick.