Fatigue Life Prediction And Reliability Optimization Design Of Turning Mechanism Based On Improved TCD

The turning mechanism is the core component of the garbage truck,and its main function is to dump the garbage into the carriage.In the operating period,the mechanism is frequently lifted and turned over,and is subjected to alternating tensile loads which can easily occur fatigue damage,resulting in the garbage truck not working properly.Therefore,in order to ensure the performance of the vehicle,it is of great theoretical and engineering significance to predict the fatigue life of the turning mechanism and research its reliability.The turning mechanism of back-feeding compressed garbage truck is taken as the research object to obtain the fatigue life prediction and reliability optimization design.Theory of Critical Distances(TCD)is improved from both stress function and critical distance to increase efficiency and accuracy,which is used to accurately predict the fatigue life of the turning mechanism.The 6σ method is used to optimize the reliability design of key components of the turning mechanism to improve its fatigue life and fatigue reliability while ensuring the strength and stiffness requirements of the mechanism.The research contents of this paper are as follows:(1)Simulation analysis and fatigue life prediction of the turning mechanism.The main components and operating principle of the turning mechanism of the existing back-feeding compressed garbage truck are explicated.Then,ADAMS is used to carry out the dynamic simulation analysis of the turning mechanism to obtain the force curves of the key components.ANSYS is used to carry out the static analysis of the key components under dangerous working condition to determine the easiest failure location of the mechanism.Based on the kinetic and static simulation results,the fatigue life of the turning mechanism is calculated using the nominal stress method,and the result has a large error with the experimental value.(2)In order to obtain the accurate fatigue life of the turning mechanism,the TCD method is used for prediction.The TCD is improved in terms of both the stress function and the critical distance to improve the computational efficiency.By analyzing the influence of the structure dimensions on the stress field around the notch,the notch depth and the structure net width parameters are introduced into the classical stress function with low order and low accuracy,resulting in a novel stress function expression with high computational efficiency and high accuracy.As the critical distance value is influenced by the notch geometry,a stress concentration factor is introduced to correct the conventional critical distance value.(3)The test validation of improved TCD method and fatigue life prediction of the turning mechanism.A notched component with regular shape is selected and its fatigue strength is estimated using the improved TCD method.A fatigue test is conducted to obtain the fatigue strength test value of the notched component.The estimated value is close to the test value thus verifying the validity and accuracy of the improved TCD method.Then the improved TCD method is used to predict the fatigue life of the turning mechanism with irregular shape.The error between the predicted values and tested values is 7.5%,indicating that the method can be used for fatigue life analysis of turning mechanism,and also providing a reference for the application of the TCD method to other irregularly shaped components.(4)In order to improve the fatigue life,the reliability optimization design of the turning mechanism is carried out.Firstly,based on the Isight software platform,the deterministic optimization design of key component of the turning mechanism is carried out to obtain the optimal design solution with fatigue life and weight as the objective responses and strength as the constraints.Secondly,based on the deterministic optimal design,the 6σ method is adopted for the reliability optimization design of the turning mechanism combined Monte Carlo and NSGA-II methods.Finally,comparing the two optimization solutions,the result shows that after 6σoptimization,the fatigue life of the turning mechanism is increased from 221,900 to530,000 cycles,and the fatigue reliability is increased from 0.71 to 0.99.