742 Dynamics Analysis of Flexible Telescopic Boom of Crane Using Sliding Joint Constraints

In this investigation, a modeling procedure of a telescopic boom of cranes is developed using the absolute nodal coordinate formulation (ANCF) together with the sliding joint constraints. Since telescopic booms can be extended 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 longitudinal deformable axis of the boom and solutions to a moving boundary problem between two flexible bodies in contact are 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 telescopic boom by considering sliding contacts between the deformable bodies. 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 elastic deformation of booms are modeled using the beam element of the absolute nodal coordinate formulation, which allows for modeling large rotation and deformation. Several numerical examples are presented in order to demonstrate the use of the modeling procedure developed in this investigation.