The Research On Semi-rigid Guardrail With An Adaptive Height

As the most important traffic safety appurtenances on expressway, guardrail plays a key role in reducing the severity and property losses of road accident. Because of the height of existing guardrail declining rapidly during the collision, rollover accident is prone to happen for vehicles with a very high center of gravity. Solving the problem properly is meaningful for improving the safety level on the road.What is mainly considered in the paper is that the accidents of vehicle rollover and overriding the guardrail occur easily when heavy vehicle with a large height of center of gravity crashes into existing guardrails. A new type of guardrail-semi-rigid guardrail with an adaptive height is brought forward, which can change its height according to the vehicle type in the accident in order to protect vehicle better. Surrounding this new guardrail structure, research in several aspects listed in the following is carried out.Firstly, literature review about development and status of guardrail is conducted, then the defects of existing guardrails are analyzed and the necessity and meaning of carrying out the research of semi-rigid guardrail with an adaptive height are put forward.Then the design idea about semi-rigid guardrail with an adaptive height is introduced in detail, including design original intention, structure form and design principle .The basic FEM theories and algorithms of impact problem are introduced also. Topics discussed include the governing equation, shell element algorithms,hourglassing control, time integration, contact-impact algorithms andmaterial model etc.Based on computer simulations, a simplified model of block-post is applied here. The emphasis is placed on impact simulations and optimizing design of block, as a result the preparatory dimension parameter of block is obtained.Finally, the finite element model of vehicle-guardrail during the collision is developed and the simulation is carried out. As a result, the final dimension parameter of block is determined. After which, the performance contrast analysis between...