The Strength And Stiffness Analysis And Optimization For The Boom System Of The Truck-mounted Concrete Pump Based On The Parametric Model

Concrete pump truck is a concrete pouring equipment, which sends the concreteto the pouring location by the boom system. The strength and stiffness of the boomsystem is directly related to the life of the concrete pump truck and the quality of theconcrete pumping, so when we design the concrete pump truck, it is necessary toanalysis its strength and stiffness.In this paper, the FE models of all components of the HB46concrete pump boomsystem, which is the object of study, are established with the method ofparameterization. The mathematical models of all components in any workingcondition, which is defined by the parameter of rotation angles of each arm, areverified. All components are imported into ANSYS and located by moving the globalcoordinate system and rotating the local coordinate system, the beam and barelements are used to simulate the pin connection between components, thus theparameterized assembly of the boom system is completed. Then, according to theactual situation, the constraints and loads are imposed to the boom system to completethe establishment of the FE model of the boom system. Only a modification of theparameters can the finite element model of the boom system be established as thewhole process is parameterized.The working conditions of the boom system are varied and changed when thepump truck is working. And only a few typical working conditions are taken intoconsideration in the conventional mechanical analysis of the boom system, and it hassome limitations to make conclusions according to the corresponding results. In orderto know better about the mechanical properties of the boom system at work,930calculation conditions are made under the principle of "lean but covered", throughcommunication with the designers and combined with practical situation.The nonlinear calculation for large deformation is necessary as the boom is longand its deformation is large at work. But at the same time, the nonlinear calculation istime-consuming and inefficient, especially in the multiple working conditions. In thispaper, linear and nonlinear calculation of the boom system in multiple working conditions is completed with batch program. The calculation results of these twomethods are not exactly the same but synchronized at the same time. And a methodthat can make the nonlinear calculation of the boom system in multiple workingconditions more efficient is proposed and can be described as following: firstly, usingthe linear calculation to identify the most dangerous working condition of each part;then, the working conditions for the strength analysis of each part by the nonlinearcalculation method are only the most dangerous ones found in the last step. Thismethod saves a lot of time and thus improves the efficiency of the analysis.In addition, in order to grasp the characteristics of the vibration of the boomsystem at work, range of the natural frequency of the boom system in each mode isobtained after the modal calculation of the boom system in multiple workingconditions and provides a more comprehensive reference to the designers to avoid theboom resonance at the boom design stage.In order to verify the reasonable of the simplification about the boom system,and the correctness of the FEM, the wireless dynamic strain test system was used totest the boom system. By comparing the strain date bettween the tested and the finiteelement result, we could get that the most of the test points is identical in addition tothe stress concentration point and the test fails points. Which proved that thesimplification about the boom system is reasonable, and the result got by FEMcalculation can be used to guide the design and the improvement of the boom systemin practice.The boom system components not only meet the strength requirement, but someplate stress of the boom is far less than the material allowable stress,which is abtainedfrom the calculation results of the HB46Concrete Pump Truck. So in strength, thematerial of the plates which is small stress is wasted. In order to reduce the weight ofthe boom system and utilize the material strength, on condition that the strength andstiffness meet the requirements, we modify the plate thickness. By repeatedlycalculating, the weight of the boom system is reduced423.76kg. In additon, in orderto reduce the luffing cylinder axial force of the boom system based on the improvedthickness, the mathematic model of the single-cylinder-six-hingepoints is established.And made the minimum cylinder force and the minimum cylinder stroke as the targetfunction, made optimization programming with genetic algorithms to optimizate thesites of the hingepoints. On the optimization results, conduct the interfere calibrationand the intensity calibration so as to make the optimization results more reasonable. In summary, established the boom system FEM with the parametric thought,calculated the strength and the stiffness with the FEM in the multi-operatingconditions, and by the field tests proved the correctness of the FEM and the feasibilityof the calculation method. So the result of calculation could provide a basis andreference for the design of the boom system in practice. The optimization of the platethickness can be made quickly by modifying the plate thickness parameters based onthe calculated result. In this way,the weight can be reduced, so the material is saved.The cylinder force and the cylinder stroke is reduced by the optimization of thehingepoints system, so the strength of the luffing cylinder is improved,and thedeformation of the boom system is reduced. Finally, the overall performance of theboom system is enhanced.