| With the rapid development of China’s transportation industry,traffic volume is increasing rapidly,especially many roads are damaged or the original routes can not meet the current requirements,so there are more and more roads into the intermediate repair or overhaul stage.The guardrail plays a vital role in road safety protection.When repairing the road,the road surface heightens is a common situation,which causes the original guardrail can not meet the protection requirements,it is a great expense to demolish the original guardrail and construct the new guardrail,and it is a good measure to increase the height of the original guardrail.In this paper,ANSYS/HyperWorks/LS-DYNA software is used to verify the three forms of integral heightening on the original guardrail.The main contents are as follows:(1)Firstly,this paper reviews the literature of vehicle impact guardrail and finite element analysis,including finite element numerical simulation and theoretical research.The numerical simulation method is determined to study the collision between the vehicle and the reformed guardrail.(2)The basic control equation in the collision is introduced,and then the boundary conditions,material model and control algorithm in LS-DYNA software are introduced.(3)HyperWorks and LS-DYNA are used in this simulation,and the vehicle model of collision is introduced.The material selection of concrete guardrail is also introduced.(4)The car model and the modified guardrail are used in the simulation crash test.First of all,the impact energy is checked.It is found that the hourglass energy does not exceed 10% of the total energy Secondly,it can be found that the three basic functions of blocking,buffering and guiding can be met by observing the running state 3 and acceleration obtained from the collision between the car and the three modified guardrails,it is found that the longitudinal reinforcement in the guardrail can not meet the strength requirement by single-slope type modification.The numerical simulation tests are carried out under various working conditions Finally,by comparing the crash results of the car with the three kinds of guardrails,including impact force,acceleration and damage degree of the vehicle,the conclusion is drawn that the impact results of the F type modified guardrail and the reinforced type modified guardrail are quite similar,are better than single-slope form of transformation guardrail.The collision angle between the car and the modified guardrail is set to be 30°,and the collision between the vehicle and the guardrail at a large angle is observed.From the perspective of the impact force and the deformation of the vehicle,the reinforced form of the modified guardrail is the better choice.(5)The simulated collision test between truck and modified guardrail was carried out.Firstly,the energy change curve was observed,and it was found that the hourglass energy did not exceed 10 % of the total energy,indicating that the calculation results were reliable.Secondly,the three modified guardrails all meet the basic functions of blocking,buffering and guiding,and the failure of the reinforced element is not found when the stress distribution of the reinforced net is observed Finally,the impact force,acceleration,damage degree and running state of the vehicle are compared and analyzed.The reinforced form transformation is the best choice for the impact of the truck.(6)The ASI values of the three kinds of guardrails were calculated by the acceleration values obtained from the collision between the car and the modified guardrail.From the classification point of view,the strengthening form of transformation is the best choice of the three transformation forms.(7)By comparing the collision between different vehicles and different modified guardrails and calculating the ASI value,it is concluded that the reinforced modified guardrail is the best choice among the three modified guardrails. |
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