An analysis of the structural dynamics of a mobile gantry crane with application to automation of container management
The work in this thesis starts with the development of a Graphical User Interface to aid the manual control of the experimental crane model and to achieve a better container management system. A structural analysis of the laboratory rig is then carried out. The technique used is to divide the whole structure into two parts: a stationary framework and a moving substructure (including its attachments). The dynamic effect of the moving substructure is represented by four equivalent, time-dependent, contacting forces (or lumped masses), and the dynamic behaviour of the stationary framework, induced by the moving substructure, is predicted by computing the responses to these forces (or lumped masses). Before the forced vibration responses can be obtained a finite element model of the scale crane rig has first to be established and validated by means of modal testing. A general technique for incorporating a standard finite element package into a procedure to calculate the dynamic responses of structures due to time-dependent moving point forces is then developed. In order to take the inertia effects of the moving substructure into account a new concept of equivalent time-dependent moving lumped masses is introduced. A general procedure has been developed to allow a standard finite element package to be extended to deal with the dynamic analyses of a three-dimensional framework subjected to the two-dimensional multiple moving masses. The theoretical results obtained are validated by comparison with experimental findings.