Research On Impact Simulation Of Easy-opening Impact Avoidance Movable Guardrail Of Expressway Median

The opening of the expressway central partition belt is designed to facilitate the passage of special vehicles in emergencies,so the movable guardrail set up here needs to satisfy the openability and flexibility.But the existing active guardrail often pays attention to flexibility and openness,but neglects the anti-collision performance.When the uncontrolled vehicle collides with the active guardrail,because of its poor anti-collision ability,the uncontrolled vehicle rushes into the opposite lane and causes many vicious traffic accidents.Therefore,it is particularly important to consider the anti-collision performance on the basis of the flexibility and openability of the movable guardrail in the central partition belt of expressway.In this paper,the collision simulation of a new type of central partition with movable guardrail is carried out.A software platform based on Hypermesh and Ls-dyna is established,which uses Hypermesh as pretreatment and Ls-dyna as solver to simulate car-guardrail collision.In Hypermesh software,each part of the active guardrail is meshed and constrained and simplified.In order to ensure the validity and authenticity of the finite element model of automobile in collision simulation,the finite element model of pick-up truck and truck is adjusted and set up to meet the requirements.Finally,the simulation test of collision between automobile and rigid wall is carried out.The validity of the finite element model of automobile is verified from four aspects:collision deformation,collision energy,seat speed and rigid wall force.The vehicle-barrier collision simulation was carried out under the initial collision conditions of 20,100 km/h,20,60 km/h lateral collision angle,and 2 m from the middle point of the open barrier with central partition and the end point of the open barrier with central partition along the driving direction of the test vehicle.The simulation results show that the moving guardrail meets the requirements of Am class anti-collision.In the midpoint collision simulation test of the guardrail,the three-dimensional acceleration of the pickup truck is 8.13g,7.81g and 6.54g respectively,and the maximum dynamic lateral displacement is 0.853m;the three-dimensional acceleration of the freight car is 4.27g,2.60g,2.15g,and the maximum dynamic lateral displacement is 0.894m.The three-dimensional acceleration of pickup truck is 7.54g,4.82g,10.10g,and the maximum dynamic lateral displacement is 0.028m.The three-dimensional acceleration of freight car is 11.03g,5.33g,7.07g,and the maximum dynamic lateral displacement is 0.346m.The three-dimensional acceleration is not greater than the specified value of 20g,and the maximum dynamic lateral displacement is less than the specified value of 1.5m.This new type of freeway central partition belt movable guardrail can effectively block vehicles,and has a guiding effect on vehicles,so that vehicles can return to the correct driving direction,while ensuring the safety of passengers and reducing the damage to vehicles.Finally,the results of finite element simulation of vehicle-barrier collision are compared with those of real vehicle-barrier collision.The results of finite element simulation of vehicle-barrier collision are reliable.The results show that the easy-to-open anti-collision barrier has certain anti-collision ability and guidance ability,and can effectively cushion the impact,reduce the damage to vehicles,and its structural rules are concise and easy to install,on the premise that the central isolation belt is easy to open and move.In addition,the research results of this paper have certain reference value for computer simulation of vehicle-fence collision and further improvement of the central partition belt movable fence currently used in our country.