Coupling Analysis Of Dynamic Response Of Ship Collision Pier And Research On Flexible Anti-collision

In the context of the continuous development of larger ships and the complex inland waterway environment,collisions between inland waterway vessels and bridge piers,as well as vessels and anti-collision devices,are a typical type of coupled problem.Researchers at home and abroad have studied collision problems for many years,but most scholars considered the coupling effect by added mass of the ship.In some cases,this method may lead to distorted calculation results.As for today’s increasingly large ships and bridges,it is not suitable to introduce a single added mass coefficient to consider the effect of the flow field.Meanwhile,the change in design of anti-collision devices is muchneeded.Most previous studies focused on the protection of bridge piers by anti-collision devices,while neglecting the protection of ships.Therefore,it is necessary to analyze the combined protection effect of anti-collision devices on both ships and bridge piers.This thesis,based on the group standard revision project of the China Technology Market Association “Technical Requirements for Anti-collision Intelligent Early Warning and Control Systems and Complete Protective Equipment for Navigational Bridge”,used the large-scale finite element analysis software ANSYS/LS-DYNA,took the outer ring Waihuan Jiangjing Yangtze River Bridge as an engineering example,and constructed a ship-bridge collision model based on the added mass method and coupled analysis method.It also considers flexible anti-collision devices and constructs a coupled model of ship,anti-collision device and flow field.In this process,a detailed study was conducted on aspects such as impact angle,ship loading,material performance aging of flexible anti-collision devices,and floating state of ships and flexible anti-collision devices during the collision process,which,to some extent,further enhances the existing studies.The series of results obtained can provide engineering references for the design of anti-collision devices and collision avoidance technology.The main research contents and conclusions are as follows:(1)The added mass method and the coupled analysis method were used to simulate the ship-bridge collision of a 7000 DWT inland bulk carrier.Using the ship impact angle and ship load as variables,and comparing and analyzing them by different calculation methods,the trends of ship collision force curves under the added mass model and coupled analysis model are explored and the differences in collision force and ship damage deformation between the two models were examined.Different impact angles and loads were used as working conditions to explore their adverse effects on ship-bridge collisions.The analysis showed that in a head-on collision,the deviation of the peak collision force was within 5%,while in a side collision,the deviation was within 20%.For side collision analysis,the coupled analysis method was adopted,which takes into account the buffering effect and “water cushion” effect brought by the flow field during the collision process,resulting in less damage to the ship than the added mass method and being more in line with the actual situation.(2)To study the impact of weakening mechanical properties of FRP self-floating anti-collision floating box materials on their anti-collision performance,samples were taken from a certain bridge’s FRP self-floating anti-collision floating boxes,then it was made into box shell components and column shell components to test its tensile,compressive,and bending mechanical properties with the waterline as a variable.The analysis showed that the mechanical properties of both types of components below the waterline were lower than those above the waterline.The material parameters of the box shell components were higher than those of the column shell components.The decrease in mechanical properties of the box shell components was about 20%,which was less than that of the column shell components 30%.Meanwhile,collision tests were conducted using scaled models of ships,bridge piers,and FRP anti-collision floating boxes.The Mean Shift algorithm was used for target tracking with crest and trough of waves as variables.MATLAB simulation analysis was then employed to study the impact of the floating state of ships and anti-collision floating boxes on collision tests under different flow conditions and their motion trajectories.The analysis showed that under the action of wave forces,the changes in the floating state of both were more intense.(3)Anti-collision devices are deployed on bridge piers to conduct a simulation of the ship’s impact on FRP self-floating anti-collision floating boxes.With the aging of flexible anti-collision device materials,the floating state of ships and flexible anticollision devices as variables for research.The analysis concluded that due to long-term exposure to water corrosion and collisions,there are structural damages in the FRP selffloating anti-collision floating boxes,resulting in a certain degree of reduction in their anti-collision capability.At the same time,the superposition of wave loads makes the collision process more severe.Meanwhile,the motion trajectory obtained through numerical simulation are compared with those under the scaled model collision tests.The analysis revealed that the error of the ship motion trajectory between the results obtained using visual analysis methods and finite element simulation was within 25% and the error of the anti-collision floating boxes motion trajectory between the results obtained using the two methods was within 35%.As for the preliminary analysis of the trajectory of the two,compared to the conclusions obtained through numerical simulation,the conclusions obtained through visual analysis using the Mean Shift algorithm,to some extent,reflect the actual collisions by taking account the coupled analysis.