Dynamics of telescopic cranes with flexible structural components

• Ten variants of crane model with different number of flexible components were analysed.
• Results of numerical simulations and test data of telescopic crane were compared.
• Influence of change in number of flexible components on results correctness was analysed.
• Selection rules of flexible components in calculation models were defined.
• Based on analyses it was shown that hydraulic cylinders should be treat as rigid.

Today׳s crane numerical models are devoid of some of the simplifications that were used in the past. These changes primarily take into account flexibilities of those structural components that used to be treated as non-deformable. Consequently, various studies analyse the same working movements based on different models.The paper presents ten variants of a computational model for a telescopic boom crane that differs in number and selection of flexible components. It has been analysed how the above-mentioned differences affect the correctness of mapping the dynamic properties of real structures via their computational models. Modelling and numerical simulations were conducted using the finite element method. The compatibility of the numerical simulation results and test results of a real structure was qualitatively and quantitatively assessed. Time characteristics and frequency characteristics after application of the discrete Fourier transformation were analysed. The analyses showed that the parameters of the modified components should be determined by taking into account their interactions with their surroundings in order to ensure correctness of the solutions. A comparison of the shape and position of spectral lines with respect to changes in the overall flexibility of the models facilitates in deciding which components should be modified and which should be omitted in order to correctly imitate the dynamic properties of a real structure.