Researches About The Dynamic Characteristics Of The Portal Crane's Boom System Based On The Groidal Braking Loads

Circumgyrate structure is the key work organization of the portal crane, according to the crane design norm, the load calculation of the drive device and transmission parts take these static loads such as rub resistance moment breeze resistance moment slant resistance moment and so on into account. As to the dynamic loads, the calculation considers only the inertial loads because of jump-start and brake. However, in the actual turn-over processor of the circumgyrate machinery, especially in the process of braking, the impact to the organization is very obvious. Now in the strength calculation of the circumgyrate machinery's parts, this distinct dynamic effect is replaced by safty coefficient.But the treatment of transforming a complicated dynamic system into a simple and man-made static system can't reflect the essence of the problem accurately. Therefore, the in-depth research on the process of dynamic loads when braking ,the analysis about the causation and influence factor of the dynamic loads' emergence is necessary to the design of the circumgyrate machinery Aim at above problems, this text treats the portal crane's boom system as a research object ,using finite element analysis and mechanism kinetics as theories foundation and analysis means ,utilizing ANSYS8.1 to research the dynamic effect of the crane boom under the circumstance of braking. Main research of the text is as follows:1) Combining related knowledge of the machine dynamics, the text introduces the configuration of the portal crane's boom system, analyzes its work principle, establishs the mechanics vibration model of the crane boom system under the circumstance of braking and gained some mechanics parameters and kinetics characteristics.2) Making use of the software ANSYS8.1, the text establishs the finite element (FEM) analysis model of the entire portal boom system.It adopts the BEAM 188 to establish the model,gives the modeling method and approach,this work settled the foundation of the crane's FEM analysis for now and future. It adopts ANSYS'sinternal command-APDL to program the command stream file. APDL is a kind of parameterized method used in modeling. It is conveniently and quickly to modify and recalculate the model in FEM analyzing.3) The text carries on the static analysis on the portal crane under two circumstances: without goods load and with full loads. Then it analyzes the calculation results and got some useful conclusions, these conclusions are good reference to making full use of the portal crane's load ability and reducing its self-weight.4) The text carries the dynamic analysis on the portal crane's boom system, primarily about the modal analysis, it gains the several former natural frequencies and additional vibration mode graphs.Then it analyzes the calculation results, judges whether the structure's dynamic characteristics answer for the design request or not, these conclusions are useful to predict the structure's dynamic characteristics and the optimization design.5) The text carries on the transient calculation of the boom system while braking suddenly. It obtains the dynamic response results including simulation nephograms of dynamics stress and displacement and curve of dynamic stress of representative nodes.lt analyzes the influences of the braking time to the structure and gains the general methods and steps in solving this kind of problem.