| The development of construction industry lead the rapid growth of engineering machinery manufacturing, tower crane as one kind of engineering machinery products with an ability of horizontal transport and vertical transport plays an important role in the construction industry. However, the collapse accident of tower crane occurred frequently in recent years due to the manufacturing processes such as design, assembly, welding, and the influence of irregularities in the operational process. How to design a tower crane with a set of economic and security became the target of the designers. With the modern science and technology developing, the testing technique and the theoretical analysis and the finite element analysis all were widely used in design and calculation of tower crane.In this paper, the QTZ80tower crane has been selected as the research object, on the basis of theoretical analysis, using section method, strain testing, modal test and other test methods, and finite element method to analyze the statical stress under various operating conditions, the dynamical stress and dynamical properties under the operating condition loading on the end of jib. Some conclusions were got as followings:1. The condition of statical strain test data show that the axial stresses pay an important role on chord stress distribution of tower crane, but the bending stress and shear stress is not obvious. This conclusion can be as the foundation of stress calculation of chord of tower crane which contains the theoretical analysis and finite element analysis. Dynamical strain test results show that there are all different dynamical factors on all different parts of tower crane, which shows that the value of the jib is a maximum one, and that of the top and connecting rod is a medium one, and that of the tower body is a minimum one, at the lifting moment of tower crane. This conclusion can provide reference for the dynamical strength analysis.2. Through comparing the results of load stress calculation among test and theoretical analysis and finite element analysis under all different operating conditions show that the three calculation results are consistent, and the results of finite element analysis is nearest to the test, the different results between theoretical analysis to the tow other methood focus on the calculation of jib, illustrated that in theory analysis, due to the simplified model, there are some errors on the theory analysis of tower crane jib.3. Through comparing the results of full load stress calculation between the theoretical analysis and finite element analysis under all different operating conditions show that the variance is large than that on calculation of load stress, due to the finite element model is closer to the actual structure and the results of finite element analysis is nearest to the test result, illustrate that the calculation results of finite element analysis is more accurate than the theoretical analysis, which can provide technical assistance for the strength design of tower crane.4. Using FFT fast Fourier transform to recognize the frequency under the results of the vibration measurement of instant unload of the operating condition loading on the end of jib, the results show that the vibration of tower crane is mainly through the top three vibration frequency. Under the environment of ANSYS software, take modal analysis to the tower crane, the results show that the frequency of the tower crane is not dependency on the connection correlation between all parts of tower crane. Through comparing of the calculation results of vibration frequency between the test and finite element analysis, show that the results of test analysis and finite element analysis are consistent, the finite element method can be used for dynamical analysis and modal forecast,of tower crane. |
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