Research On Driving Stability Of Tank Vehicles Based On Equivalent Mechanical Model Of Liquid Sloshing

Tank vehicles are widely used in liquid cargo transportation and the proportation of tanks vehicles in commercial trucks has been increased for recent years. While tankers have a great significance in promoting industrial development and improving national living standard, frequent traffic accidents were also caused, which lead to casualties and property loss. In addition, about two-thirds of tanker accidents caused environment pollution.Investigation has found that rollover is the most important tanker accident type and most of tanker rollover accidents happened on the curved section of highways. Lots of effort has been made to study the reason for this phenomenon. Due to the changing of vehicle driving states and the easy flow characteristic of liquid, liquid cargo in partially-filled tanks moved and dashed against the tank walls, which bring bout dynamic load transfer and the increasement of rollover torque. Liquid sloshing in partially-filled tanks greatly weakend vehicle handling stability. Therefore, the research on transient liquid slohing in partially-filled tanks is the frist step for studying handling stability of tankers.There is a huge difference in physical property betwwen liquid and solid. Hence, conventional methods for solving liquid sloshing are not suitable at all because of the coupling of liquid movement and vehicle driving. The limitation of hydrodynamic equations made the most researches on dynamic analysis of tank vehicle are sloved by multi-body dynamics analysis software. This method restrict the changeover from research achievement to real productive forces. The design of vehicle active safety system and vehicle performance evaluation are hardly achieved using numerical analysis results. If we can describe liquid sloshing in partially-filled tanks by a equivalent mechanica model while the mechanical modal has quite the same dynamic characteristics with the liquid sloshing, then the liquid sloshing problem is transformed into a machine movement problem and the coupling of liquid sloshing and vehicle driving can easily be solved.Therefore, the paper tried to slove liquid sloshing in partially-filled tanks by equivalent mechanical modal, then studied tanker diving stability based on that. The main contents are as following:(1) The hydrodynamic analysis of liquid sloshing in partially-filled tanks and the collection of flow parameters. Fluid dynamics theory was used to definite flow model and establishthe governing equations. The initional and boundary conditions of hydrodynamic equations were also decided according to practice loading conditions and liquid cargo transportion demands. The solution method of differential equations were analyzed and realistic flow parameters were collected.(2) The extraction of the dominate modal of liquid sloshing. The Fourier transform was used to do the frequency-domain analysis of flow parameters. The composing of frequency and its amplitude were investigated. On the basis of preliminary analysis results of flow parameters in frequency domain, modal analysis was conducted and the vibration modes were obtained. According to the vibration modes, dominate modals for liquid slohing were cleared and definited, as well as their influencing factors were analyzed.(3) Quasi-Static analysis of liquid sloshing. On the basis of dominate modals of liquid slohing and their impacting factors, liquid slohing estimation was carried out using the quasi-static method. Slohing effects and the moving trajectory of liquid were acquired. Then the relation between estimation results and practice sloshing effects were studied and the characteristic of liquid moving trajectory was analyzed.(4) The establishment of equivalent mechanical modal for liquid sloshing in partially-filled tanks. Mechanical equivalent principle, similarity theory and dimensional analysis were used to investigate the mechanism of transforming liquid sloshing to mechanical motion and the principles for establishing equivalent mechanical model were definited. Combination with the QS analysis results, equivalent mechanical model was established. The motion equation was derived and the mechanical matching relationship beween mechanical model and liquid sloshing was analyzed.(5) The derivation and solution of mechanical model parameters. According to the analysis results of mechanical matching relationship, mechanical model parameters that should be sloved were decided and the parameter functions were derived. Replying on the realistic liquid sloshing effects, model parameter expressions were established in function of tank shape, liquid fill level and liquid physical properties.(6) The study of tank vehicles driving stability based on equivalent mechanical model of liquid sloshing. The coupling factor connection liquid sloshing and vehicle driving was analyzed and decided, then kinetics model for tankers were established. MATLAB was used to simulate vehicle driving stability and its driving characteristics were investigated. An effort was made to discover the main factors that impact vehicle driving stability and liquid sloshing strength.