Research On The Finite Element Analysis And Optimal Design Of The Base Structure For The Truck-mounted Concrete Pump

With the accelerating pace of China's urban construction, as well as the substantial using of commercial concrete, the truck-mounted concrete pump has becoming an indispensable construction machinery in the architectural industry.In our country, the concrete pump has been developing just in recent years. It is a kind of high value-added concrete pouring equipment, and special vehicle with the integration of mechanics, electronics and hydraulics. Due to its advantages in many aspects, such as mechanization, automation, good environmental performance, high rate of concrete pouring, reliable quality, good mobility and etc, the concrete pump is now representing the development of concrete casting machine and becoming the first option of people in the construction field.As carrying the vertical load and bending moment of the upper part, whether the design of the base structure is reasonable or not will directly affect the stability of the vehicle. The finite element analysis of the base structure is very necessary.In this paper, various types of finite elements are used in modeling the base structure. After the finite element analysis in all load cases and dynamic strain testing, the accuracy of finite element analysis is verified and the loads for calculation are modified. The structural optimization is the last part. Details are as follows:1,the finite element modeling and calculation of multiple working conditionsWith the characteristics of different finite elements, the base, the front and back leg, the sub-frame and chassis of the structure are modeled respectively. And the automatic assemble and calculation through APDL in total working conditions are finished. The traditional studies of the base structure mostly focus on its static analysis in one or more conditions, however, force and stress of the base structure during the entire process of construction can't be fully explained. Therefore, the realize of static strength calculation in multiple conditions, the extraction and analysis of result data and then the obtain of disciplines in changes and distributions of the stress all can, on the one hand, provide data for the structural design improvement and detailed research of the dynamics character; on the other hand, provide a method for the calculation of other types of base structure and the similar structures.2,the linear calculation of the base structureWith the establishment of the finite element model of the base structure and the application of constraints and loads to it, the linear static analysis in full boom-rotary conditions are finished. After the analysis of the result, the deformation and stress distribution in the most dangerous condition, the stress concentration zone and weak parts of various components are all known. A systematic calculation method based on ANSYS to the base structure is formed. And the optimization of corresponding parts are finished. All of these provide a strong theoretical basis for the series product's design and remodeling design.3,the strain test of the base structureThe strain test of the base structure is based on the dynamic electrical testing method. The strain pieces are attached to the selected tested points on the corresponding parts of the base structure. The test is executed in the boom-rotary conditions to measure the strain in specific direction of each tested point. The values by testing and finite element calculation are sorted out to have an analysis of the deviation and relative deviation between them and a comparison of strain curve to verify the accuracy of the FEA results and modify the loads for calculation.4,the structural optimization of the base structureWith the results of linear static calculations in Chapter IV, the optimization in thickness of the base structure from both the stiffness and strength is finished. The optimal programs and results of the base, the front and back legs were given.For the base part, by decreasing the thickness of specific shells, the value of maximum stress is reduced from 1103MPa to 666MPa, the values of large stress are cutting down or even dropped below the yield. And the area of regions with large stress is also reduced correspondingly.For the front and back legs, by modifying the types and thickness of local structures, the local concentration of stress is eliminated, the weak parts are strengthened, the stiffness is reduced, the strength is improved and the materials are more fully utilized.