Research The Safety Of Vehicle Under Crosswinds In Methods Of Simplification

In recent years,extreme weather often occurs,with the running speed of trains in our country continuously improve vehicle safety under crosswind operation gradually,especially in the vehicle with special landform areas(such as Lanzhou,coastal areas)operation,even if the vehicle speed is not high(about 100km/h),vehicle the wind effect is also prone to derailment,overturning,causing heavy casualties and property losses,so the research of vehicle in crosswind safety with practical needs.This paper summarizes the common methods to study the safety of vehicles under the action of crosswind by looking up a large number of documents.The research methods can be roughly divided into wind tunnel experiments,field experiments,computational fluid dynamics(CFD)and multi-body dynamics simulation methods.These two methods have been applied to the study of the safety of high-speed trains in China.These methods perfect guide our country high-speed train and the design of the line.However,the practice shows that the low-speed train will also overturn and derail in the event of sudden strong crosswind.This paper introduces the foreign standard GM / RT2142,EN14067 and AS7509.1.This paper explores a low-cost and reliable method for evaluating the low-speed safety of vehicles under cross-wind conditions.Firstly,the paper introduces the calculation method of the GM/RT2142 standard in the wind direction and wind speed curve in the evaluation of vehicle rollover in crosswind operation safety,aiming at the design speed of 160km/h power car,the qualitative parameters of GM/RT2142 standard by using a single variable method,the study found that the quantitative calculation analysis: the standard reflects the influence of suspension the way of anti overturning ability of the vehicle;of a power car,the axle load of each increase of 5%,area A,height of H decreased by 5% per vehicle critical overturning wind speed increase 1.13,1.83,2.1m/s respectively;changing the vehicle roof of top profile is the most effective method to improve the capsizing ability of locomotive and rolling stock.Secondly,the simplified method of analyzing the safety of the vehicle under the action of crosswind in the standard EN14067 is explored,and the torque balance formula of the three-mass model is derived.The formula shows that if the unbalanced force direction and the crosswind direction are in the same direction,the aerodynamic overturning moment of the vehicle will be larger,the vehicle is more prone to overturn in operation.Using the prediction formula and three mass model in the standard,the wind characteristic curve of a domestic 160km/h power vehicle is drawn by using MATLAB,and the speed limit of the vehicle is evaluated.It is suggested that the speed of the vehicle should be adjusted to the equilibrium speed in a timely manner to ensure the safe operation of the vehicle.Close,can guarantee the operation safety.Finally,the multi-body dynamics model is established by using SIMPACK software,and the simulation is carried out according to the method of applying maximum overturning torque in AS7509.1 standard,and the running safety of the power vehicle is evaluated by thedynamic index wheel load reduction rate.The analysis shows that the wheel load reduction rate does not exceed the standard when the speed of the power vehicle reaches 250km/h.In addition,the influence of cross wind direction on vertical force and wheel load reduction rate is studied.It is found that the unbalance force and wind direction in the same direction will worsen the vertical dynamic index,and the conclusion can be used to guide the installation of windshield wall in curve section.The simulation results further verify the analysis of the previous simplified method conclusion.