| Boom crane is an important large-scale construction machinery in the modernization of construction,due to the limited level of technology and insufficient accumulation of relevant production experience,most of the boom cranes produced by many enterprises in China are facing the boom and hydraulic cylinder weight is too large,the boom expansion process is not smooth and local stress concentration and other issues,these problems will not only lead to the overall performance of the crane to decline,but also make the crane fuel consumption large,mechanical efficiency low.Carbon fiber reinforced polymer is an advanced composite material with carbon fiber as the reinforcing phase,which has the advantages of low density and high strength,high specific modulus,fatigue resistance and corrosion resistance.In recent years,with the reduction of its mass production costs,its application in engineering has become more and more extensive.In this paper,the telescopic boom of a certain type of truck-mounted crane is used as the research object,and the research method of combining theoretical analysis,simulation calculation and experimental research is used to design and study the carbon fiber reinforced polymer boom.The main research contents are as follows:Firstly,on the basis of fully understanding the research status and development trend of crane telescopic boom,carbon fiber reinforced polymer and its molding process,cross-section optimization,friction and other related fields,the engineering force of crane boom is analyzed and calculated,the theory of composite stiffness strength and the mechanical analysis method of composite material bent thin-walled beam are theoretically derived,and the general design principles of carbon fiber reinforced polymer are summarized.Secondly,in view of the friction and wear problem between the boom and the carriage in the telescopic boom,the friction and wear performance between the two boom materials of carbon fiber reinforced polymer and steel and the slider were studied by experimental method,and the differences in the friction mechanism,friction coefficient and wear rate were analyzed.The data show that the friction coefficient,fluctuation of friction coefficient and dynamic-static friction coefficient difference between carbon fiber reinforced polymer and polyethylene,polyoxymethylene,MC nylon and MCS nylon are all smaller than those of steel,but the wear rate of carbon fiber reinforced polymer is greater than that of steel,and it is about 2 times more.Then,using ABAQUS finite element simulation software as an auxiliary calculation tool,combined with the theoretical basis of composite mechanics and structural optimization,the bending and torsional resistance of different sections of the boom are simulated and calculated,and the shape optimization of the elliptical section with relatively good comprehensive performance is optimized.On the basis of friction test and cross-section shape optimization,the preliminary design of the carbon fiber reinforced polymer telescopic crane boom was completed by using the composite material design method,and the simulation model was established and calculated,and the performance difference between the carbon fiber reinforced polymer boom and the original steel boom was compared and analyzed,and the results showed that the selfweight of the carbon fiber reinforced polymer boom was reduced by more than 55%under the premise of bending resistance and torsional stiffness greater than that of the original steel boom.Finally,combined with the laboratory conditions,the production of carbon fiber reinforced polymer boom test pieces was completed by the process method of vacuum bag compression molding,and the simulation and test of three-point bending were carried out,which verified the reliability of the simulation calculation results of this paper,and the nonlinear change law of "displacement-loading force" of carbon fiber reinforced polymer boom under three-point bending conditions was preliminarily obtained through the test data. |
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