Research On Direct Strength Assessment Of Asphalt Carriers With Independent Liquid Cargo Tank

With the vigorous development of infrastructure construction in China,the market demand for asphalt is increasing.Domestic asphalt has been unable to meet the market demand,and the imported asphalt has become an important source of supply of infrastructure materials in China.The imported asphalt is transported to China's coastal ports by water,so the demand for asphalt transport ships is increasing in the transport market.This greatly promoted the development of asphalt ship.The independent cargo tank asphalt ship is a type of ship developed for transporting high temperature asphalt liquid cargo.The independent cargo tank is not rigidly connected to the main hull structure,but is supported on the main hull structure by the support block.At the same time,limit devices in different directions are set to control the displacement of the independent cargo tank in the main hull.Its unique structure can effectively control the loss of heat.The structure of the independent cargo tank type asphalt ship is complicated,and the support block is only subjected to pressure.And the ship carries high temperature liquid cargo.The focus of the design is on the force distribution of the support blocks of the independent cargo tanks and the effect of high temperatures on the hull structure.This paper analyzes the key technology of the direct assessment method of independent tank cargo asphalt ship.The rod element is used to simulate the independent tank support block and limit structure,and the finite element method is used to calculate a 7500 t independent tank asphalt ship.Comparing the calculation results of two different iterative analysis ideas,one is to directly remove the tension unit,and the other is to modify the tension of the tension unit to eliminate its influence.It is concluded that the latter is more reasonable.The hull structure was evaluated based on the calculation results of the second iterative analysis method.At the same time,detailed stress analysis is carried out on the limited structure area with high stress.The linear gap elements are used to simulate the independent tank support block and limit structure,and the contact and separation of the main hull and the independent tank are simulated by the opening and closing stiffness of the gap element.The calculation results of this method are compared with the calculation results of the rod element iterative analysis,which proves the feasibility of this method.And the influence of the clearance between structure on calculation is also analyzed.Finally,the hull temperature field distribution is obtained by heat transfer calculation of the cabin structure by MSC.Patran/Nastran software.Thermal stress calculations are then performed on the hull structure.By comparing the calculation results with or without temperature load,,the necessity of thermal stress analysis for independent tank type asphalt ship is proved.In addition,this paper analyzes the concerns of the ship's thermal stress analysis.Then,considering the influence of high temperature on the mechanical properties of the material,the strength of the target ship's hull structure is checked.The research in this paper summarizes the direct assessment and evaluation method of independent tank cargo asphalt ship.It has reference significance for the structural design,assessment and plan review of this type of ship.