The Strength Design Of The Saddle And Stability Analysis Of The Tractor Semi-trailer

With the sustainable and healthy development of the national economy, the highway transportationenterprise has a great process in our country. Because of the big freight volume, low-cost and high efficient,the Tractor Semi-trailer have gradually causing concern and attention in all aspects. It can be predicted thatthe Tractor Semi-trailer will gradually play an important role in the road transport and lead the developmentdirection of the road transport. The Saddle as a coupling device between the tractor and semi-trailer, notonly connects them as a whole, but also carries the load and impact during transportation, it becomes one ofthe most sensitive security equipments of the Tractor Semi-trailer. The structural analysis of Saddle is veryvaluable and important. With the complexity of the Saddle structure and the load conditions duringtransport, using classical mechanics method to analyze its structural strength can not meet the requirementsof modern products design.In this paper, the finite element analysis techniques is applied in structural analysis of the Saddle. Thefinite element model is built through the HyperMesh software. The first eight modal frequencies and modalshapes of the Saddle FE model are calculated. Secondly, add the appropriate boundary conditions, thestrength properties of the Saddle under static and dynamic load spectrum are also analyzed. The resultshows that the strength of the structural meets the design requirements. Based on the strength analysis ofthe structure, a size optimization of the key part of Saddle structure is taken. Taking the thickness of thestructure as the design variables, with the first modal frequency and structure vonMises stress within acertain range as the constraints, the weight of the structure is optimized to the minimum. The weight of theoptimized structure is reduced9.96Kg compare with the original structure, and the first modal frequencyincreases14.5%. The result shows that the optimization achieves the goal of lightweight structure.According to the basic theories of vehicle handling stability, unlike general vehicle dynamicsmodeling, the affections of the structural parameters are considered during build the deflect stability modeland roll stability model of the Tractor Semi-trailer. And then base on the kinetic equation, steady-stateresponse analysis, dynamic characteristics analysis, stability analysis (root-locus method) and transientresponse analysis are taken. The steady-state response analysis shows the affections of the structural parameters of the Tractor Semi-trailer to steering characteristics; the dynamic analysis gets the stabilityfactor of the Tractor Semi-trailer; the specific impact of the various parameters to the Tractor Semi-trailerhandling stability is got by the root locus method; the transient response analysis gets the responsecharacters of the Tractor Semi-trailer with the front wheel step input. The results and conclusions can makea guidance for the design of the Tractor Semi-trailer at engineering applications. The formula among theanalysis could be applied in testing and verifying a new design, in order to shorten the development cycleof the Tractor Semi-trailer.