Chapter 20 – Collapse Analysis of Ship Hulls

This chapter discusses collapse analysis of ship hulls. The purpose of this chapter is to develop a procedure that enables the calculation of the ultimate hull girder strength, which is as accurate as Smith's method for pure bending. It is based on the FEM approach, and the procedure may save manpower and computer CPU, as much as the ISUM and the superelement approach can. First, this chapter presents an accurate and efficient finite element procedure for the static and dynamic collapse analyses of ship hulls. Second, mathematical equations for the estimation of ultimate moment and moment interaction are then presented and discussed. Third, the Smith method for hull girder analysis is modified to account for the effect of corrosion defects and fatigue cracks. Finally, practical applications to the ultimate longitudinal strength analysis of ship hulls and response analysis of tankers involved in collisions are also demonstrated. This chapter outlines the computer program SANDY, and the computational procedure implemented in the program. In this chapter, five typical application examples of ship collapse analysis are presented and the three examples have been chosen to validate the proposed analysis procedure. This chapter has shown that the plastic node method, along with the new element, is in agreement with existing approximate methods for hull collapse loads and, moreover, provides much more information about the progressive failure.