Research On Direct Assessment Of Whole Ship Structure Of The Pure Car Carrier

The continuous development of China's automobile industry and automobile trade brings a strong demand of the Pure Car Carrier,and the roll-on roll-off transport of China is facing good development opportunities.The successful storage of the Three Gorges Dam and the application of the ship lift level have improved the navigation conditions of the Yangtze River system and improved the shipping efficiency.It greatly stimulates the development of the inland river Pure Car Carrier.For the convenience of vehicles,The Pure Car Carrier does not set the transverse bulkhead in the cargo area.It also restricts the size of web beams and stringers,and the deck above the main deck is almost through.That make the ship's stiffness,longitudinal strength,transverse strength and Grillage strength face serious challenges.The ship generally sets multi decks to improve economic efficiency and usually sets several rows of struts between the two decks to reduce the span of the deck longitudinal and lateral length.Designers pay more and more attention to the structural strength of the Pure Car Carrier with an increasing demand of Ro-Ro ship.This article analyzed the method of Pure Car Carrier direct strength assessment,and worked on the key technologies and basic processes.Take 850 Pure Car Carrier as an example,the full ship FEM model of this ship is created for full ship structure FEA.In the full ship FEM model,the loads of gravity,car loads and outboard water pressure and so on are applied properly.After balancing the outboard water pressure,the stress and deformation are analyzed under rules requirements.The proper local model is intercepted from the whole ship model,and the appropriate load and boundary conditions are applied to check the transverse strength and grillage strength of the target ship.The safety of the structure is evaluated,and the results are compared with the direct calculation results of the whole ship structure strength.The total longitudinal strength of most components of the target ship can meet the requirements of the rules,and the results shows that the transverse strength of the target ship and the local strength of the plate frame can meet the requirements of the rules.Direct strength assessment of whole ship structure is more comprehensive and specific than the rules calculation,and it is better to ensure the safety of the structure.Through comparison,the results of the transverse strength and the strength of the plate frame are less than that of the whole ship structure,but the front two are not enough to ensure the safety of the structure.This paper summarizes the basic processes of FEM direct strength assessment of whole ship structure of Pure Car Carrier,and it can provide reference for future research.The article designs C deck of Ro-Ro ship by flexible design in order to solve the problem of transverse strength of Ro-Ro ship.The advantages and disadvantages of two designs against traverse loads are summarized by comparing the deformation and stress of the rigid design and the flexible design,and it provides a reference for designers to design Ro-Ro ship.