In this investigation,a modeling procedure of a telescopic boom of cranes is developed using the absolute nodal coordinate formulation together with the sliding joint constraints.Since telescopic booms are extracted and retracted under various operating conditions,the overall length of the boom changes dynamically,leading to the time-variant vibration characteristics.For modeling the telescopic structure of booms,a special care needs to be exercised since the location of the sliding contact point moves along the deformable axis of the flexible boom and the solution to a moving boundary problem is required.This issue indeed makes the modeling of the telescopic boom difficult,despite the significant needs for the analysis.It is,therefore,the objective of this investigation to develop a modeling procedure for the flexible telescopic boom by considering the sliding contact condition with the dynamic frictional effect.To this end,the sliding joint constraint developed for the absolute nodal coordinate formulation is employed for describing relative sliding motion between flexible booms,while flexible booms are modeled using the beam element of the absolute nodal coordinate formulation,which allows for modeling the large rotation and deformation of the structure.
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