Gun Cradle Large Displacement Of The Body Along The Recoil System Of Space-time Finite Element Modeling Study

Under the background of a National Defense Project, this thesis is concerned with space-time finite element modeling theory and method for a canon barrel with large displacement by combination of theoretical analysis, numeric calculation and experiment.Basic modeling theory on space-time finite element method is analysised. Combining with the classical case of string vibration under moving inertial load, the algorithm program for solving structural dynamic problems is compiled. Based on classical examples, the results are compared with the exact solution, the Newmark method, Wilson-θmethod and Central difference method, which verifies the accuracy and stability of this algorithm.A time-varying mechanical model of simply supported beam and cantilever beam with moving force or moving mass is established. Based on the traditional finite element mass matrix and stiffness matrix, space-time finite element mass matrix and stiffness matrix in each time step is derived by using the iterative scheme to update the displacement and velocity. The dynamic response is calculated with the examples of moving force or moving mass with a certain speed subjected to simply supported beam and cantilever beam. The results are compared with exact solution, Newmark method and Wilson-θmethod, which further demonstrates the effectiveness of space-time finite element method.Time-varying dynamics model of the canon barrel with large displacement is established, the corresponding space-time finite element numerical algorithm is deduced. The cradle and barrel are simplified as cantilever beam, moving rigid body, moving spring mass, moving spring rigid body and moving beam. The time domain and space domain is discreted by space-time finite element method, time-varying dynamics equation group is derivated, the dynamic response of the canon barrel with large displacement is calculated through numerical calculation.The vibration characteristics of the canon barrel with large displacement is tested and researched. The correctness of theoretical modeling is verified by the results comparing of theoretical calculation and experiment.The preliminary research findings of numerical calculation using space-time finite element for the cannon barrel with large displacement achieved in this paper can be of certain reference to in-depth theoretical study on dynamic design of the large displacement time-varying.