| It is an urgent problem to be solved in the engineering that the driving safety of the mixing truck in urban road.Frequent and serious rollover accidents are a great threaten to the safety of drivers,urban roads and construction projects.The weight of the truck is large,and the position of the centroid is higher than that of other projects,and it will change dynamically with the stirring of the fluid in the mixing drum.These characteristics directly led to the poor rollover stability of the mixing tru ck.Moreover,it is also more likely to cause rollover accident because of the driver non-standard operation in the process.As the base of the whole vehicle assembly,the structure of the frame directly affects the height of the vehicle centroid.So,to carry out the research on the fluid motion and frame structure influence on the vehicle centroid,and then put forward the scheme of improved mixing truck rollover stability,all of these ha ve important theoretical significance and practical value for the design of the mixing transport vehicle and driving safety.Based on the above analysis,this paper uses several simulation analyzed method,Analyzed the relationship between the movement of concrete fluid in mixing drum and Vehicle centroid and the vehicle rollover stability.Then put forward scheme of the frame of main and auxiliary integrated improvement and mixing drum rotational speed active control to improve mixing truck rollover stability.The main contents and conclusions of this paper are as follows:1.Using Flow-3D software to simulate the rheological parameters of self-compacting concrete.The movement of the fluid in the mixing cylinder is simulated by using the calibrated rheological parameters,and the results of the three direction displacement and lateral acceleration are obtained;2.Establishing the mathematical model of rollover of the mixing truck.Based on the results of 1,the relationship between the motion of centroid and the vehicle rollover stability is analyzed.Get that the safety speed of the vehicle is reduced at least 2.68% by the movement of the fluid,and the rollover stability of the vehicle becomes worse.Then,analyzed the influence of tube geometric parameters: installation angle,helix angle,load and speed on the fluid centroid motion and vehicle turning safety speed.Get a set of parameters which the stability of the mixing truck is better;3.Using Hyperworks software to establish the finite element model of truck frame.And the influence of the mass center offset and l ateral force on the force of the frame is analyzed.Get that the maximum stress of the frame is improved at least 13.51%,and the stress becomes worse.Then,design the main and auxiliary integrated frame of the mixer truck.The Mechanical properties of two kinds frame structure is analyzed under the turning condition.Get that the advantages of low center and high strength of the frame can make the maximum stress reduced at least 17.55%;4.Using ADAMS software to establish the model of the whole vehicle with different frame structure,and running vehicle simulation under various conditions.Get the relationship between the Fluid motion,the structure of the frame,the speed of the vehicle,the rotation angle of the steering wheel,the speed of the mixing drum and the stability of the mixing truck.Based on the above analysis,this paper puts forward a scheme to improve the stability of vehicle rollover.A scheme for improving the stability of vehicle rollover is proposed.Through the above analysis we get that the movement of the fluid in the mixing drum will reduce the stability of the vehicle,and the stress of vehicle frame will become worse.The improved integrated frame not only improves the mechanical characteristics of the frame,but also improves the stability of the vehicle because of the advantages of low gravity center.Based on the above analysis results,the active control strategy of the mixing drum speed is put forward,which provides a new way to improve the stability of the mixing truck. |
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