Initial Damage Evolution of Bubbles at the Interface of Concrete-Epoxy Coating Under Regular Waves
The initial bubble damage at the interface of concrete-epoxy coating of Marine buildings ac-celerates evolution under the action of waves,which leads to mechanical erosion of the coating.Based on the basic theory of cohesion model,the cohesion unit was developed again,and the initial damage cohe-sion model of epoxy coating-concrete matrix interface was established to simulate the interface fatigue damage process under the action of regular waves.The effects of bubble formation angle,area and ec-centricity on the initial damage evolution under the action of regular waves were analyzed.The results showed that the expansion evolution of the initial damage at the coating interface is divided into three stages:pre-damage evolution,fatigue accumulation and damage expansion.Before the initial damage e-volution,the dynamic response of the initial damage is concentrated at the bottom of the bubble,espe-cially at the edge of the semi-minor axis.After the semi-minor axis edge debonding failure,the fatigue damage of the semi-major axis accumulates rapidly and the debonding failure occurs.In the debonding expansion stage,the debonding area expands outward from the bottom of the initial bubble damage,and the debonding rate of the semi-minor axis is greater than that of the semi-major axis,finally forming a circular debonding area.With the increase of bubble area and eccentricity,the maximum stress and strain of cohesion unit increased,and the coating debonding time shortened.With the increase of bubble formation angle,the maximum strain of the cohesion unit at the bottom of the bubble decreases gradual-ly,the strain concentration effect of the cohesion unit at the bottom of the bubble weakens,and the coating debonding time increases.Therefore,if the initial bubble damage area can be reduced during construction,and the eccentricity and generation degree of bubbles can be controlled,the service life of the coating can be effectively prolonged.
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