Analysis Of The Inland River Asphalt Ship Inland River Thermal Stress Parameter Sensitivity And Fatigue Strength

Asphalt boat is a kind of transport ship with high added value,due to the presence of structures such as heating devices and thermal insulation,makes asphalt boats difficult for construction.The temperature of asphalt-laden oil pitch is between 120°C~180°C,high-temperature liquid cargo not only greatly increased the temperature gradient of the ship's double shell structure,but also it brings obvious additional temperature stress to the ship's components,it is even possible for the local component to yield,thus endangering the safety of the structure.But,there has been less research on inland river asphalt ships,therefore,the evaluation of the structural strength and fatigue strength of such ships has a higher engineering value.This article uses a Inland river asphalt boat as an example,completed temperature field calculation,overall strength analysis and fatigue strength analysis,summarizes some features of Inland river asphalt boat structure and fatigue strength.The specific research work and achievements are as follows:First,the distribution of overall loading conditions and environmental conditions under the operating conditions of asphalt ships was introduced.Combined with the empirical formulas of CCS "Fatigue Guidelines for Ship Structures",loads such as wave bending moment,hydrodynamic pressure and ship motion acceleration are calculated.Secondly,the MSC.Patran software is used to establish a coarse mesh model of the hull structure,above calculation load is directly loaded on the hull structure or the load is applied through the MPC point associated with the center of gravity.Then carry out the finite element calculation,consider when the loading conditions are not changed,exist or not exist thermal stress,the force of the hull structure is affected.According to the influencing factors of thermal stress,three main parameters are selected to analyze and calculate the thermal insulation thickness,asphalt temperature and ship hull external temperature.The stress calculation results based on the four working conditions,the stress concentration area is screened,the study has found out the principle of selecting the wave load of a ship,the influencing factors of the overall strength and the areas where fatigue damage may occur.At the same time,considering that the ship is damaged by the outer side during the voyage,due to the hull water ingress,a large temperature gradient will occur at the inner side of the ship,which will increase the stress of the hull,and thus may cause danger during the navigation of the ship.Finally,introduce the nominal stress method and hot spot stress method based on S-N curve and Miner cumulative damage principle,combine the analysis of overall strength with the requirements of the specification to derive high stress areas.Through hot spot screening and the establishment of fine grids,calculating the cumulative fatigue strength of nine fatigue hot spots by the nominal stress method,then select the L1 longitudinal bone and the position of the heel of the hopper to calculate the hot spot stress,comparing the results of two fatigue strength calculation methods can be found,although there are some differences in the results of the two methods,the cumulative fatigue damage of the upper deck and inner floor is greater than that of the longitudinal bone joint at the side.