The Research For Influence Of Road Surface Roughness On Cargo Constraint System

Currently, in our country, normative documents about the operation specification of tie down is being constituted. Before this, it is necessary to make an systemic analysis of the property of the tie down when truck accidents happen. During transportation, road surface roughness of incentive for cargo constraint system exists all the time. The unevener of road surface, the more dangerous of vibration and shock to cargo constraint system and the higher frequency of accidents. This paper analyses the property of the tie down when rollover accident happens, educes the minimum number of tie down to prevent cargo apart from truck.This paper first introduces knowledge about the roughness of road. Based on the generating mechanism of random input model of single wheel, a filtered white noise model for the random inputs with four wheels correlated is established. At the same time, selecting a EQ1156W3 truck and two TD50B tie downs as the restraints of cargo, it concludes two physical models of Road-truck- cargo restraints system:direct binding and binding over the top. It is takes cargo and its restrains as the quality spring damping system in effect, then calculates the equivalent stiffness of the two different forms of binding. As needed, the dynamic model of Road-vehicle-cargo constraint system planar three-freedom, five-freedom and space eight-freedom is developed.The random road model is constructed by Matlab/Simulink based on the study of the relation of stochastic road space and time frequency power spectral density and root-mean-square. The stochastic exection signals are produced, and the vertical displacement of the B and C leveal uneven road was bulit by simulation with vehicle 25m/s. According to the model for the random inputs with four wheels correlated, it calculates stochastic exection singals about C leveal road.Change space eight-freedom model into the standward of space-state model, so it is good for calculating road-vehicle-Cargo Constraint System when using software. Because some parameters, such as the speed,lashing angle and so on, influence the stress of tie down.To facilitate the calculation analysis, using VB software interface design function, for the hybrid programming method VB and Matlab, the call of Matlab in VB application program was realized through establishing linkage between VB and Matlab ActiveX server. Meanwhlie the calculated results visualiation, convenient analysis. Finally in different level road, change incentives bound Angle and speed parameters or increase the number of tie down, calculated the stress of tie down.According to the American standard, get the minimun number of 2 tie downs to prevent cargo which the mass of 8000kg apart from vehicle. But the actual calculation results show that in D, E level road, the tie down is out of safe working condition,and Validate the method is not suitable for domestic situation. Consequently, this thesis provide some basis for state to constitute peration specification of tie down.