| With the ever-increasing number of Chinese electric vehicles and the extensive use of central barriers for urban roads throughout the country,the number of collisions between cars and guardrails is increasing.At present,the urban road isolation barrier has poor anti-collision performance,and often a large number of guardrail pipe spatters are generated during the accident of the electric vehicle collision road central isolation guardrail.The splashing bar structure after the guardrail is damaged is easy to hit the road pedestrian and sink.The bottom of the vehicle causes crushing and penetrating damage to the battery pack at the bottom of the electric vehicle.Therefore,the collision of the car guardrail not only considers the damage of the guardrail,but also the secondary damage to pedestrians and cars on the road.At present,there are few researches on automobile and urban road isolation guardrails at home and abroad.The main research is on the collision damage of highway guardrails.Based on the simulation research method of mature guardrails,the finite element model of high-precision guardrail with solder joint failure is first established.On the basis of on-site accidents,a high-speed small-angle and low-speed large-angle car collision scheme was developed.The simulation results show that the welding of the vertical pipe and the crossbar is prone to failure and fracture when the guardrail is impacted.The elastic potential energy of the pipe is released at the moment of breaking,and the vertical pipe flies out at a higher speed.The stress distribution of the lower crossbar is greater than 230 MPa,resulting in severe plastic deformation,and the front end of the beam is exposed.The paper further establishes the simulink model based on the equation of motion state,and describes the displacement and velocity of the guardrail in three-dimensional space.Based on this,the possible impact position and collision speed of the splash trajectory on pedestrians are analyzed.In order to study the secondary damage mechanism of the scattered guardrails on the vehicle,the paper establishes a finite element model of the refined FEM algorithmbased on the internal structure of the battery pack,and adopts the SPH algorithm suitable for high-speed impact large deformation research for the case of large internal battery deformation.A battery cell model was established based on the internal structure of the battery cell and the Crushable Foam material model.The finite element model of the battery pack structure of the FEM algorithm is coupled with the finite element model of the battery cell of the SPH algorithm to simulate the impact of the guardrail penetration on the bottom of the battery pack.The research results show that the SPH algorithm can reasonably simulate the large deformation of lithium ion batteries.The horizontal squeezing force is the main factor that causes the opening of the box to penetrate into the damage mode.In this damage mode,the internal battery deformation and displacement are intensified,which poses a greater threat to the safety of the battery pack.Finally,using topology optimization,the working condition is set to the direction and size of the guardrail when the car collides.The optimal conditions are set as the minimum displacement of the guardrail,and the optimization target is the minimum quality.After the optimized iteration,the valve value is 0.6,and the distribution of the guardrail material is mainly observed.Focus on the column and the lower rail and the vertical pipe weld.Based on this,the thickness of the lower crossbar and the profile of the column is increased,the welding method is improved and the collision simulation is performed again.The simulation results show that the deformation of the guardrail is reduced,the stress distribution at the interface is reduced,the splash condition is improved,and the crashworthiness of the guardrail is improved,which is of great significance for improving the safety of the battery pack in the collision of the guardrail. |
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