The Dynamic Analysis For The Flexible Crane System Of The Heavy Travelling Overhead Wroking Truck

The overhead working truck, especially the folding-jib overhead working truck,is one typical kind of flexible multi-body mechanical system. With the development of computer technology and the application of the high strength material in the engineering plant, and also with the requirement of the market which requires the mass and lightness of the mechanical equipment, make the overhead working equipment more and more light and flexible, all the changes bring the problem of nonlinearity of geometry and the analysis of flexible multi-body mechanical system. Moreover,the natural frequency become lower,and the frequency of the excited force raise caused by the increase of the running speed, all the changes may cause heavy vibration of the mechanical system, at that time, the custom analysis method that regard the component as rigid body is no longer suitable for modern design and analysis. To supply an accurate dynamics analysis becomes one important mean to guarantee the safety and dependability.Many experts and scholars are focus on introducing dynamics analysis to mechanism to provide theoretical foundation for optimized design, dynamics optimization and control.According to the special demands and working environment, the style of the truck was choose, the plan and the dimension of the frame and working device are also decided. After that, the main structure's strength,stiffness and stability are checked by the widely used FEA software ANSYS. The following task are based on the dynamics analysis of the working device.First, the traditional dynamics theories were analyzed and compared, and advantages and insufficiency of every method were summarized. On the basis of this,the two new methods the Equivalent Finite Element Integrated Method and the high-precision and high-efficiency KED Method are introduced in this paper. In the following text,the two new methods are used to analysis the modle of heavy mobile overhead working truck.In the Equivalent Finite Element Integrated Method, the equivalent principle that was suitable to be equivalent for any form of component was given. The quality and the inertia of it were equivalent to the centroid or to the two ends by the way of static and dynamic drawing together. The element equivalent mass matrixes of typical components after equivalent were produced by the equivalent principle. The elements were integrated and assembled by FEM. Account the key point of building dynamics model to be setting up two-stage tensor Tia and three- stage tenser Tibc and assembling the equivalent mass matrix. It is made up easily and can be solved quickly. The high-precision and high-efficiency KED Method has the similar type of equations as the traditional KED, The equations, which are in fact ones of dynamics of flexible multi-body systems, can then be solved by KED method. The accurate element equations of motion, which are derived directly from dynamics of flexible bodies, are transformed into the similar forms as KED equations. Then it adopts the spirits of traditional KED to establish and solve the equations of system, so it is not only as simple as traditional KED analysis but also more accurate. The progress of the two methods mentioned above to establish dynamics model was simple, rapid, standard, unified and convenient to program and assemble.According to the dynamics theories of multi-body systems mentioned before, the FEM program were compiled based on Compaq Visual Fortran 90 and MATLAB7.0,and the modal analysis to the turntable and working equipment by ANSYS also has been done in this paper.