Computing Methods And Application Development Of Longitudinal Strength Of Damaged Ships

A series of terrible accidents such as collisions, stranding, grounding, etc. happen in ship operations. Damages are produced by attack as artillery fire, torpedoes, bombs, etc. in military operations. A damaged ship will not founder because of sufficiency of damaged stability, but the further damage would be happened on account of insufficient of intensity after collision or grounding. Therefore, the residual strength of ship structure after damage is much accounted of people more and more. Accidents are unavoidable. Casualties and economic losses are reduced as possible if residual strength is checked and the emergency schedule is presented rapidly when damages are happened. So much so that victory of battle is influenced fatefully.The reasons of further damage as follow:the change of load is produced by loss of buoyancy and variation of weight which changes by water ingress or loss of cargo; loss of intensity is produced by structural damage.The main content and achievements of this dissertation are as follows:1) In buoyancy calculation of damaged ship for any floating condition, the hull lines are expressed by cubic spline functions,14 scenarios of intersections of a waterline and a section are discussed. Computing of intersections, wetted surface areas and elements of buoyancy for any heeling conditions is achieved by the application.2) Based on added weight method, a traditional method of successive approximation for loads calculation is improved which changes of weight and adjustments of floatation that has heeled are considered. Computing of elements of buoyancy, shear forces and bending moments in any condition of damages is obtained by the application.8 types of basal sections of compartments are summed up, and effects of loading conditions of cabins for a damaged ship are considered.3) From the angle of service operating requirements, calculation of characteristic parameters for asymmetrical sections is researched and achieved by the application. Computing and checking of longitudinal and shearing strength for damaged hull girders are obtained which based on the linear elastic theory. Effects of water ingress of compartments, athwartship inclination, sidesway of the center of gravity, and asymmetry of damaged structures for longitudinal strength are considered.4) The longitudinal strength of damaged ships in any conditions of water ingress, sizes and locations of crevasses can be calculated by the application. Ship strength in any status after damages can be checked whether satisfies the service requirements rapidly though factors of motionofship, buckling or plastic distortion are not considered. The general types of single hull ship are applicable. Hazardous situations of damages can be predicted in structural design. Residual strength of current status of damages is estimated in good time, and emergency schedules can be taken suitably.