The Through Type Girder Of The Gantry Crane's Finite Element Analysis And Optimization Design

Gantry crane,a lifting machine for transferring large material is widely applied in national economic construction and plays an important role in modernization as well.As the practical application of gantry crane has increased in recent years,its potential problems and disadvantages are gradually appeared.In working condition,the traditional crane has a disadvantage that the stresses and the strains for its girders are excessively large as a result of the forces in the simple form.Based on the characteristics of through tied arch bridge and its structural form,this article will present the structure improvement of the main beam for a double girder gantry crane and a new structure design of the through type main beam.This new design has changed the strained state of the main beam,and improved its mechanical properties to reduce the manufacturing costs by the materials-saving.At the beginning of the article,a new structure design of the through type girder was completed by establishing the mechanical models of the straight and through type girders.After comparing the moment and deflection on the two main beams,the theory was found that the through type girder had the better mechanical properties than the straight girder.Then,by using the finite element software,ANSYS,the static analysis of the two beams in the dangerous working conditions were made to compare the results of the simulation analysis between the new and old design,to determine the strength and distribution of the stress and strain on the girders,it proves that the static strength and static rigidity of this through type girder is really superior to that of the straight one.Particularly,create the mathematical model for optimized girder design and finish the measurement optimization of the through type girder with the FEM software ANSYS,then make static analysis on the optimized girder.With all that,the theory,the quality of through type girder is 12.6%lower than that of the straight one,which has largely saved the cost,is proved under the premise of satisfying the static strength and rigidity.Considering the engineering practice,a system consisted of bridge,trolley,reel and hanging wheels was built as a system dynamics model,and the theoretical operating frequency of the gantry crane could be determined.The modal Analysis worked out the natural frequencies and the corresponding vibration mode.By the further analysis of the theoretical operating frequency and the low-order natural frequency,the resonance should not occur at the gantry crane.Based on this,the continuing analysis of the harmonic response to the main beam found that the frequency led to the maximum amplitude at the main beam was the third-order natural frequency,which illustrated this frequency made the main beam tend to be faulted at "Y" direction in working condition.Therefore,the through type girder should be strengthened to increase the stiffness at this direction.The dynamics analysis not only verified that the dynamic characteristics of the through type girder reached the design requirements,but also gave ability to design a better main beam by determining the weakness of the beam,which could improve the working safety and comfort of the crane.In conclusion,this new design,which referenced to the bridge structure,and had through type main beam,not only changed the stress model,improved the strained state,and reduced the weight for the purpose of cutting the manufacturing cost,but also provided a reference for the new structure design of the main beam and the lightweight design of gantry crane.