Crashworthiness Analysis And Structural Optimization For Anti-collision Guardrail

Anti-collision guardrail is an important facility to ensure the safety of road traffic and important places.Improving the crashworthiness of guardrails can reduce the property loss in traffic accidents,protect the safety of traffic participants and block out unsafe factors.The thesis relies on horizontal project “Crashworthiness Analysis for Anti-collision Guardrail”.The main contents and conclusions of this thesis are as follows:(1)Theoretical analysis of crashworthiness for the anti-collision guardrail.The formula for calculating the maximum lateral collision force is derived by using simplified mechanical vehicle-guardrail non-rebound collision model.The joint strength of the guardrail was checked and the weighted average height was calculated according to the “Design Specifications of Highway Safety Facilities”.The calculation results show that the guardrail can meet the A protection level with a high safety factor by using M16 bolts of grade 5.8 and above between the frame and the pillar.The welding strength of the frame just meet the requirements with only 1.17 safety factor.The guardrail meets the A anti-overturn level with the 1.88 meters weighted average height.(2)Simulation analysis of crashworthiness for the anti-collision guardrail.A vehicle-guardrail collision simulation model was built and the simulation was carried out under the specified conditions and the severe conditions.The "stumble phenomenon" occurred during the collision between the vehicle and the guardrail under the specified conditions simulation.Under the severe conditions,the guardrail effectively slowed down the vehicle,but the frame was broken and the vehicle crossed the guardrail.Therefore,this type of guardrail can’t meet the actual requirements.(3)The horizontal loading test for the anti-collision guardrail.The test applied horizontal load to the guardrail through the simulated collision contact surface.The structural deformation of the guardrail was observed.The results showed that the welded connections between the upper/lower beam and the side beams are the weakness of the guardrail structure.Therefore,the guardrail parts can’t make full use of plastic deformation to absorb more loading energy,which greatly reduce its crashworthiness.(4)Structural optimization for the anti-collision guardrail.In order to improve the strength of the welding connections of the guardrail frame,reinforced corners were added to the guardrail and the base boss height was improved.Then the crashworthiness of the optimized guardrail was simulated.The comparison shows that,the optimized guardrail’s absorption of collision energy has been increased by 20.5% and the optimized guardrail has a better ability to stop vehicles in multiple layouts.