| Air cushion belt conveyor is a kind of continuous conveying equipment,which has simple structure and few moving parts.It runs on uniform air cushion support.Compared with trough belt conveyor,it uses a large number of idler supports for transportation.It has the characteristics of stable operation,low maintenance cost,no deviation,easy to realize closed conveying and less energy consumption.Air cushion belt conveyor is commonly used in coal,grain,food,power,port,building materials and other departments to transport various bulk materials.It is important to study the pressure distribution of air cushion for improving the arrangement of air holes,making the conveyor belt run smoothly,and providing parameters for the selection of air chamber and fan.The pressure of the air cushion depends on the pressure of the material and the conveyor belt.In this paper,the lateral(perpendicular to the running direction of the conveyor belt)pressure distribution of the air cushion is solved.The calculation method of lateral pressure distribution of material to conveyor belt is deduced by using the earth pressure theory,and the lateral pressure distribution of material is solved by using the water pressure theory.The correctness of the calculation method of the earth pressure theory is verified by the discrete element simulation.The results show that the difference between the calculation results of the water pressure theory and the earth pressure theory is 4.38%.The difference between the software simulation method of DEM and the theoretical calculation method of earth pressure is 3.56%.The water pressure theory can be used as a simplified approximate method to calculate the transverse pressure distribution of materials.In this paper,the equivalent transverse modulus of elasticity of conveyor belt is identified by using beam element and shell element,respectively,with the method of troughability test of conveyor belt sample in ISO 703 standard and the finite element calculation software ABAQUS.The Euler Bernoulli beam model is established,and the formula for calculating the equivalent transverse elastic modulus of conveyor belt is derived.The differential equation of Euler Bernoulli beam is simplified by Fertis’ method.The nonlinear equations are simplified by the complex Simpson quadrature formula,and the nonlinear equations are solved by the conjugate gradient method.At last,the calculation software of the equivalent transverse elastic modulus of the conveyor belt is developed by Visual Basic.Net.The difference between the calculation results and the transverse elastic modulus of the conveyor belt identified by the finite element method is 3.38%.The calculation method of transverse elastic modulus of conveyor belt is deduced by the thin plate th eory and Galerkin method.The result is beyond the range of elastic modulus.It is speculated that the reason is that the deflection of the sample of conveyor belt is more than 5 times of the thickness assumed in the thin plate theory.The pressure distribution of the conveyor belt with different lateral bending stiffness on the surface of the material carrying pan is solved by the solid mechanics simulation method.The results show that with the increase of the lateral bending stiffness,the pressure distribution of the conveyor belt on the material carrying pan increases.The transverse pressure distribution of air cushion subjected to material and conveyor belt is analyzed by solid mechanics simulation method and two-way fluid solid interaction method.The results show that the air cushion pressure calculated by the solid mechanics simulation method and the two-way fluid solid interaction method is consistent in the trend,but the air cushion pressure distribution obtained by the fluid solid coupling method is more continuous,and the result of the solid mechanics simulation method has a sudden change. |
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