Lightweight Design Of LPG Semi-trailer’s Tank Using High Strength Quenched And Tempered Steel

LPG(Liquefied petroleum gas)is the important source of clean energy and chemical raw materials,and the main type of trading LPG in China is by land carriage.With the growing consumption of the domestic LPG,the ministry of transport of the PRC had increased the intensity of the administrative penalties to the overload behavior,the large volume and lightweight LPG transport semi-trailer had become the inevitable trend of transporting type.Liquefied petroleum gas semi-trailers as the main special equipment for domestic transporting,the tank’s weight generally accounted for more than 60% of the quality of the whole semi-trailer’s weight.So the lightweight designing of the tank will directly affectting the vehicle’s lightweight level.Under the premise of the rules and standards of the PRC,the large volume,high loading capacity,more efficiency and low costs semi-trailer plays an important role in response to the national call for energy saving.Taking the co-development LPG semi-trailer manufactured by the high strength quenched and tempered steel that the minimum tensile strength limit is 715 MPa as the research object in this paper,through the research of the basic property and the optimal design point at the structure of the semi-trailer to improve the stress condition of the main pressurized components of the tank,and to thin the shell of the tank to reduce the curb weight.On the researching of the material in this paper,base on the high strength quenched steel which the minimum tensile strength limit is 610 MPa,adjusting the chemical composition of the steel,change the rolling and heat treatment process,research the mechanical properties,welding performance,fatigue performance,the welded joint,Crack Tip Opening Displacement(CTOD),stress corrosion resistance of the steel plate and the forming control of the tank’s head.On the designing of the structure,created the 3D model from top to bottom by ANSYS first,formed the nodes and elements by meshing,simulated boundary condition and applied load according to the GB/T 19905-2005 “Liquefied Gas Tanker”,then used the stress classification method from the JB 4732 “Steel Pressure vessel-Design By Analysis” to determine the convergence result and verified the design structure to meet the actual operating conditions.According to the calculation and the related experimental results,a prototype semi-trailer had been manufactured and through the type test by the national professional vehicle identification department.The shell of the prototype vehicle’s tank thinner than the original type 1mm at least,could reduce the weight about 700 kg,achieved a prominent lightweight effect.