Study On Direct Analysis Approach To Simulate Longitudinal Launching Process Of Ship And Marine Structures

The launching process is one of the most complex and dangerous procedures of the building and installation of ship and marine structures. A minor mistake could cause disastrous economic losses or even casualties. The study on launching process is significant for improving launching technologies, avoiding dangers and evaluating the strength and stability of the structures. According to the geometric characteristics of the waterplanes, structures are divided into two categories, including the Isolated Waterplane Structures(IWS) and Separated Waterplane Structures(SWS). On this basis, the direct analysis approaches for static launching of IWS, dynamic launching of IWS and dynamic launching of SWS are developed. These approaches are collectively referred as the direct analysis approach.The direct analysis approach is developed based upon the direct analysis method for hydrostatics and intact stability and multibody dynamics. The commercial finite element analysis software ABAQUS is adopted as the analyzing platform. The advantages of the approach are:(1) converting the cumbersome computation of Bonjean curves and integration of loads to the building of finite element meshes;(2) exerting loads directly onto the surface elements of the structures, without any approximation;(3) obtaining all the motions and forces of the whole procedure only by one run of the program.First, the direct analysis approach is applied to simple examples, including the ordinary launching of a rectangular barge, a Wigley ship and an offshore jacket. The results are compared to the analytical solutions. Then, the approach is applied to rather complex examples, including the launching of a 46,000 DWT tanker and the self-upending launching of an offshore jacket. In addition, the analyzing consumptions of time are listed. The results show that the direct analysis approach is accurate and capable of handling complex structures and advanced launching process efficiently. In summary, the direct analysis approach can be a new way to analyze the launching process of ship and marine structures and has a potential to be applied to engineering cases.