Research On The Ultimate Strength Of Stiffened Plate With 921A Steel

With the rapid development of China’s shipping industry,the lightweight requirements of ships are becoming stronger and stronger,and the application of high-strength steel materials has received increasing attention.921A steel is a low-alloy high-strength steel which is independently developed in China.The steel has excellent strength and plastic properties which can maintain quite stable physical properties and proper ductility in a certain temperature range.The stiffened plate is the basic structural component of ships and Marine structures.Its buckling or plastic failure usually leads to the overall damage of the hull beam,which brings safety hazards to the navigation of ships.Nowadays,the effect of 921 A steel on the buckling failure mode and ultimate bearing capacity of hull girder and stiffened plates is not clear;The experimental data on the buckling failure mechanical properties of 921 A steel hull plate reinforcement structure is lacking,so it is necessary to carry out related theories and experiments research to provide the necessary technical support for the development,design,and application of the new 921 A steel ship type.This research can also be applied to the safety assessment of other Marine structures(including polar platforms,space stations and deep-sea submersibles)under complete and damaged conditions,which has important theoretical value and engineering practical significance.In this paper,tensile tests at room temperature and high temperature of 200,400,and600 are carried out according to relevant specifications.The mechanical parameters such as elastic limit,yield stress,tensile strength,and fracture strain of 921 A steel at various temperatures are obtained.Theoretically,the real stress-strain curves at various temperatures are drawn.This chapter studies the influence of temperature on the properties of 921 A steel based on the experimental results,and fits the mathematical relationship between the yield strength of 921 A steel and temperature according to the mathematical model.Then design the 921 A steel stiffened plate member according to the experimental environment and tooling conditions,use the three-stage loading method to carry out the ultimate strength test,obtain relevant data such as displacement,load,deformation,time,and verify the accuracy and finite element simulation method.According to the test results,the accuracy and reliability of the finite element simulation method are verified,which provides an effective guarantee for the follow-up finite element expansion research and empirical formula derivation.In the end of this paper,the ultimate strength of general steel and 921 A steel stiffened plate is compared from the perspectives of buckling failure mode,buckling utilization factor and effective width.A new empirical formula applicable to 921 A steel is proposed based on the classical mathematical model.At the same time,this chapter studies the influence of temperature on the ultimate strength of the stiffened plate,and analyzes the applicable scope of the new empirical formula of 921 A steel under high temperature environment,which provides theory and data support for predicting the ultimate strength behavior of 921 A steel hull structure.The innovation point of this paper is to study the influence of the material properties of921 A steel on the ultimate strength of the stiffened plate and its corresponding temperature effect,and put forward a reliable empirical formula within the range of normal temperature to400,which provides theoretical reference and ultimate strength evaluation method for the industrial application of 921 A steel.