Finite Element Simulation Study Of Vehicle Collision With Semi-rigid Guardrail Based On LS-DYNA

China has developed transportation network and a large number of bridges.The guardrails of built bridges can meet the protection requirements for a period of time when they are open to traffic.With the development of automotive industry and Chinese guardrail industry standards,a large part of existing guardrails can not meet the requirements.Bridge guardrail,as the last line of defense to protect the safety of vehicles,is very important.Metal beam-column guardrail has been widely used in long-span Bridges due to its advantages such as small dead weight,flexible structure and strong energy consumption capacity.This thesis combines the standard section of semi-rigid guardrail and van truck to study the safety performance of guardrail.The specific work are as follows:Firstly,starting from the classification and evaluation criteria of the guardrail,the advantages and disadvantages of each kind of guardrail and its applicable environment are briefly introduced.And taking metal beam-column guardrail as an example to analyze the interaction mechanism and energy dissipation principle of the collision between vehicle and guardrail.Secondly,after the 3D model of guardrail is established in CATIA,Hyper Mesh is used to mesh the model and define their material and properties.Under appropriate simplified conditions,several groups of "vehicle guardrail" finite element models based on Ford F800 are established,and some of its calculated control parameters are introduced.Finally,the influence of the thickness changes of guardrail posts and beams on the safety performance of guardrails is studied.On this basis,the influence of rubber pad and O-shaped steel obstruction block on various functions of guardrail is studied.The calculation results of the three semi-rigid guardrail systems are analyzed in different working conditions,and the results show that:(1)All guardrail combinations can smoothly intercept moving vehicles without stumbling and driving out of the guide frame.When the rigidity of the guardrail increases,the maximum displacement value of the column becomes smaller,the energy consumption capacity decreases,and the cushioning performance becomes worse;(2)After the rubber pad is added,the energy consumption and guiding ability of the guardrail are also increased to a certain extent,and the various indicators of the cushioning function are reduced to different degrees compared with the original system,which proves that it is feasible to increase the rubber pad to improve the cushioning performance of the guardrail;(3)After replacing the fixed connector with an O-shaped steel obstruction block,the guardrail has a good guiding ability,and its energy consumption and buffering capacity are significantly improved.However,as the thickness of the obstruction block increases,its deformation and energy consumption capacity will be reduced.