Simulation And Analysis Of Ride Comfort Of The Tractor Semi-trailer With The Balanced Suspension

Compared with the conventional vehicle and the full trailer, the tractor semi-trailershows irreplaceable advantages in long distance bulk cargo transportation. In thehighway transportation the tractor semi-trailer is playing more and more importantrole. There are great differences between the structure of the tractor semi-trailer andthe conventional vehicle, and the research of the tractor semi-trailer has practicalsignificance. With the development of semi-trailer to the direction of large scale andhigh speed, the ride comfort of the tractor semi-trailer is unsatisfactory. To meet thedemand of drivers’ comfort, cars’ working status as well as the integrity of cargo, theresearch on ride comfort of tractor semi-trailer is particularly necessary.The key problem of the tractor semi-trailer’s ride comfort simulation is to establish asuitable model of tractor semi-trailer vibration model and to describe the roadroughness accurately. At present, at home and abroad, lumped parameter method iswidely used in the establishment of the tractor semi-trailer vibration model, becauseit need less parameters, and the simulation results are accord with the actualsituation. However, the tractor semi-trailer vibration model is imperfect, and theexisting vibration model can’t faultlessly reflect structure characteristics of the tractorsemi-trailer.According to the demand of enterprise that cooperated with, this paper is focused onthe establishing vibration model of six-axle tractor semi-trailer equipped withbalanced suspension. Several road roughness description methods and therelationship between them are also studied. Then the ride comfort of six-axle tractorsemi-trailer equipped with balanced suspension is analyzed. Sensitivity analysismethod was used to analyze several main parameters that effects the ride comfort ofsix-axle tractor semi-trailer equipped with balanced suspension. This study has offered a theoretical basis for ride comfort control, improvement and optimization ofsix-axle tractor semi-trailer equipped with balanced suspension.The main contents are as follows(1) Establishment of vibration model of six-axle tractor semi-trailer equipped withbalanced suspensionCombined with the enterprise’s practical six-axle tractor semi-trailer equipped withbalanced suspension. The cab mounting, balanced suspension and saddle aresynthesized considered. A planar vibration model with thirteen degree-of-freedomautomobile system is built. The elastic and damping characteristics of saddle aredescribed by the elastic model composed of spring and damper, and all thetheoretical formula are derived, and this has lay the foundation for improving thetractor semi-trailer ride comfort simulation model.(2) Advanced studies of Sayers pavement model and international roughness indexIRIThere are two pavement roughness description methods, and they are the powerspectrum density method and the international roughness index algorithms. Thestandard pavement model and the Sayers pavement model are power spectrumdensity methods that are commonly used.In order to find out the more suitable road roughness description method for ridecomfort simulation of tractor semi-trailer train, the study includes the difference of theSayers pavement model and the standard pavement model, and the way to convertthe standard road model into Sayers model. The definition and formula ofinternational roughness index IRI is studied. The IRI standard model of vehiclesprung mass and unsprung mass vertical displacement difference frequencyresponse function and velocity difference frequency response function are deduced.Establish international roughness index IRI in the spatial and temporal frequency way,analyzes the relationship between international roughness index and standardpavement model.The results of the study show that, although the Sayers model is a road model provided by ADAMS, but there are still limitations. When the standard pavementmodel is used to describe the road roughness, it is equivalent to internationalroughness index IRI. But the standard pavement model, is more suitable for tractorsemi-trailer ride comfort simulation.(3) Six-axle tractor semi-trailer equipped with balanced suspension ride comfortanalysisBased on national standards GB/T4970-2009, established two simulation methodsof the six-axis tractor semi-trailer equipped with balanced suspension, one for roadrandom excitation and another for pulse excitation. The formulas of two methods arederived. Under road random excitation and different speeds, the human bodyacceleration curve and the absolute value of the maximum acceleration are derivedthrough simulation. Under random excitation and commonly used condition, Thepower spectral density curve and RMS value of conventional and special vibrationresponse of and vibration response are also derived. According to driving conditions,and also to meet the requirements of human comfort, working conditions and tractortrailer cargo integrity sensitivity analysis perturbation method is used to analyze theride comfort of six-axis tractor semi-trailer equipped with balanced suspension. Thestiffness of elastic element and the damp of damping element are selected asinfluencing parameters, get the evaluation and sensitivity. In view of the value ofsensitivity is small, and it’s inconvenient to use, the concept of relative sensitivity isproposed. Identify the main parameters that affecting tractor semi-trailer train’s ridecomfort, and then the parameters are sorted.The results showed that the relative sensitivity can be well used in analyzing theparameters of six-axle tractor semi-trailer equipped with balanced suspension ridecomfort effect, it is worthy of application and promotion.