Numerical Analysis Of Interface Damage Evolution Of Coating On Offshore Pier Structures Under Wave Action

The splash zone is located in the sea-air exchange interface area,and it is in the dry-wet alternate state for a long time.The low-frequency reciprocating impact of the wave on the coating accelerates the corrosion damage of the coating,and the corrosion failure of the coating generally originates from defects such as bubbles.Therefore,under the repeated impact of wave load,the coating of the offshore structure exacerbates the extended evolution of the initial damage such as bubbles on the interface of the coating,causing mechanical erosion,leading to early corrosion failure of the structure.The problem of coating erosion caused by initial damage such as bubbles has become a hot and difficult problem to be solved in the near-shore engineering disaster prevention and mitigation.Through the numerical simulation of FLOW-3D and ABAQUS,the distribution characteristics of the wave impact force on the surface of the pier column structure and the diachronic curve of the impact process are analyzed,and the bubble evolution law of the pier column structure coating under the action of waves is revealed.The main research contents and conclusions are as follows:(1)Wave impact process characteristics of the splash zone.Based on the Navier-Stokes equation and the RNG k-? model,a three-dimensional numerical model of the wave trough is established.The distribution characteristics of the wave impact force on the surface of the near-shore columnar structure and the duration curve of the impact process are studied.The results show that the order of the point pressures at the five locations around the structure(?=0°,45°,90°,135°,180°)in the same horizontal plane is:P?=0°>P?=45°>P?=180°>P?=135°>P?=90°.In the vertical direction,the point pressure at the hydrostatic surface The maximum point pressure value of each elevation exhibits a linear decrease with the increase of the distance from the hydrostatic surface.Under the same conditions of wave height and period,the water depth has no effect on the total horizontal force and the maximum point pressure of the hydrostatic surface.Under the same water depth and period,the wave height has a significant influence on the total horizontal force of the structure,showing a positive linear relationship and a total horizontal level.The magnitude of the force change and the surface point pressure of the structure become larger as the wave height increases,but the change period is the same as the wave period;the change of the wave period has little effect on the total horizontal force of the structure.(2)Evolution law and expansion trend of coating interface damage.The pillar,coating and bubble models were constructed by NX 9.0,imported into ABAQUS for assembly and mesh local encryption,and the ABAQUS/Standard analysis module was used to investigate the evolution process of bubble damage at the structure/coating interface during wave action.response.The strain at the center of the bubble increases linearly with the increase of the wave height,and the influence range also increases with the increase of the wave height;the magnitude and range of the strain are basically not affected by the wave period;the magnitude of the strain appears as the diameter of the bubble increases.The number increases,but when the bubble diameter is large enough,the change in strain is gradually reduced by the influence of the increase in the diameter of the bubble.The bubble deformation is longitudinally evolved from the central position,and gradually develops with the increase of the wave force,and gradually expands to both sides.With the increase of the wave height,the lateral expansion speed is accelerated,and the longitudinal expansion speed is gradually slowed down.(3)Establish a damage constitutive model of epoxy resin coating that considers wave elements.By analyzing the relationship between wave height,period and bubble diameter and strain,the strain peak increases with the increase of diameter and wave height.The strain and diameter show a polynomial relationship,while the strain and wave height have a positive linear relationship.The magnitude of the strain peak is not affected by the wave period,but the change period is the same as the wave period,and the relationship between strain and bubble diameter and wave height is obtained:?=0.0018H·In(d)+0.0088H,and based on the periodic variation of wave force,the stress of epoxy coating material under repeated impact for wave load is established.The relationship between strain and wave element changes.By comparing the fitted curve with the numerical results of different load spectrum loading conditions,the strain and stress duration curves are basically consistent.