A Cannon Cradle Dynamic Finite Element Analysis And Fatigue Life Prediction

Although artillery-related technology has been more mature, various reliability problems in the use occured, which becomes the main factors of decreasing the artillery battle effectiveness. Fatigue failure of key components of artillery is one of the problems. The work of this article is concerned with the fatigue strength of the cradle under specific conditions by means of computer simulation, and to predict its fatigue life.First of all, the cradle structure and its working conditions are analyzed, and then the difficulties in cradle structural analysis is figured out. PSD method in terms of finite element analysis and frequency-domain is presented to investigate the fatigue life of gun cradle after reviewing the new fatigue theory at home and abroad.The finite element modeling approach for the cradle is discussed, and the method of using both shell element and block element is applied to model cradle. The finite element model of the cradle is constructed by means of HyperMesh package. The strength simulation is carried for the cradle under static conditions through MS C.Nastran, which theoretically proves that the structural strength requirement is satisfied. Then the dynamical analysis is conducted, including modal analysis, transient response analysis and frequency response analysis. The natural frequencies and corresponding vibration modes of the cradle are retrieved, as well as the maximum value of dynamical stress, the stress-time history, and frequency response of stress within a specified band is evaluated.Finally, in light of the data from the above analysis, and properties of loads and materials, fatigue damage model in frequency domain based on the software of MSC. Fatigue is constructed, from which the area with maximum fatigue damage is found, and then the fatigue life of cradle is predicted. In addition, a finite element model with consideration of welding is built. The stress of such model is computed and the fatigue life is attained, which is compared with the predicted results from the first proposed model.The model and data in this project can provide a theoretical reference to the design of artillery cradle, and the related research.