Digital Design And Simulation And Research On Dynamic Characteristic Of Large Marine Mechanical

Large marine grab excavators are the main tool for river dredging. With a large number of ports and long inland waterways in china, marine excavators, especially large-capacity ones are in great demand. This thesis is based on the Hangzhou major innovation project of large frequency control marine grab excavator development and industrialization by the Zhejiang University and Hangzhou Heavy Machinery Co., Ltd. Taking large capacity6m3large marine grab excavator as the research object. The paper not only has theoretical significance, but also has practical engineering value. Its innovation content includes:(1) The structure optimization of large marine grab excavator:Based on finite element analysis, by applying digital design simulation technology, after modeling, simplifying components, meshing and setting material property the finite element model of the marine grab excavator was established. Excavator simulated by comprehensively considering six conditions. The displacement and stress contours were obtained. Then the impact of working loads and working angle to the static parameters was studied. Besides, the optimized structure fulfilled the security requirement and its load distribution was more reasonable, with reduction in material consumption.(2) Established large marine grab excavator’s dynamic mechanical model:Based on the multi-body system dynamics and virtual prototyping theory, according to the structural characteristics of various components, rigid-flexible parts division was studied. Combining multiple software platforms, obtaining modal characteristic parameters of boom, building the boom and other parts model, modeling derricking wire ropes, connecting all parts using constraints, the virtual prototype model of large marine grab excavator was established, as the foundation for the simulation.(3) The dynamics parameters and reliability analysis of large marine grab excavator: Based on the model, by applying a time-varying load, excavator dynamics parameters were simulated. The dynamic performances including the displacement, velocity and acceleration curves of components, the hinge joint forces, and the derricking ropes sleeve forces curves and stress contours of flexible body boom were studied. Furthermore, the affect of the occurrence time of sudden unloading to dynamic performance was studied. These kinetic parameters provide the basis to the fatigue analysis and reliability analysis.