Effect of Fluid Flow Nonlinearities on the Dynamic Behaviour of Cylindrical Shells Subjected to a Supersonic Flow

2010 ◽  
Author(s):  
R. Ramzi ◽  
A. A. Lakis
Keyword(s):  
Fluid Flow ◽  
Supersonic Flow ◽  
Dynamic Pressure ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Third Order ◽  
Aerospace Vehicles ◽  
Stiffness Matrices ◽  
Aeroelastic Design ◽  
Frequency Variations

An analytical model is presented to predict the influence of nonlinearities associated with supersonic fluid flow on the dynamic and stability behavior of thin isotropic cylindrical shells. The method developed is a combination between finite element method, sander’s shell theory and nonlinear aerodynamic theory (third-order piston theory). The shell is subdivided into cylindrical finite elements, the displacements functions are derived from exact solutions of Sanders equations for thin cylindrical shells and the influence of stress stiffening due to internal or external pressure and axial compression is also taken into account. Expressions for the masse and stiffness matrices are determined by exact analytical integration. With the nonlinear dynamic pressure, we develop nonlinear matrices: stiffness, damping and coupling matrices for flow. The nonlinear equation of motion is then solved using a fourth-order Runge-kutta numerical method. Frequency variations are determined with respect to the amplitude of the motion for different cases. This is a powerful model to predict linear, nonlinear vibrations and stability characteristics of cylindrical shells subjected to external supersonic flow that can be applied for the aeroelastic design of aerospace vehicles.

Buckling of Circular Cylindrical Shells Using a Displacement Function

1974 ◽  
Vol 96 (4) ◽  
pp. 1322-1327
Author(s):  
Shun Cheng ◽  
C. K. Chang
Keyword(s):  
Boundary Conditions ◽  
Axial Compression ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Displacement Function ◽  
Combined Loading ◽  
Trial Solution ◽  
Governing Differential Equation ◽  
Circular Cylindrical Shells ◽  
The Stability

The buckling problem of circular cylindrical shells under axial compression, external pressure, and torsion is investigated using a displacement function φ. A governing differential equation for the stability of thin cylindrical shells under combined loading of axial compression, external pressure, and torsion is derived. A method for the solutions of this equation is also presented. The advantage in using the present equation over the customary three differential equations for displacements is that only one trial solution is needed in solving the buckling problems as shown in the paper. Four possible combinations of boundary conditions for a simply supported edge are treated. The case of a cylinder under axial compression is carried out in detail. For two types of simple supported boundary conditions, SS1 and SS2, the minimum critical axial buckling stress is found to be 43.5 percent of the well-known classical value Eh/R3(1−ν2) against the 50 percent of the classical value presently known.

Imperfection sensitivity of unstiffened cylindrical shells under external pressure

ce/papers ◽  
2021 ◽  
Vol 4 (2-4) ◽  
pp. 1789-1796
Author(s):  
Esmaeil Azizi ◽  
Natalie Stranghöner
Keyword(s):  
Cylindrical Shells ◽  
External Pressure ◽  
Imperfection Sensitivity

Grinding Fluid Flow Field Modeling and Multi-Parameter Numerical Analysis Based on Smooth Model

2010 ◽  
Vol 156-157 ◽  
pp. 948-955
Author(s):  
Guang Yao Meng ◽  
Ji Wen Tan ◽  
Yi Cui
Keyword(s):  
Fluid Flow ◽  
Numerical Analysis ◽  
Flow Field ◽  
Dynamic Pressure ◽  
Grinding Wheel ◽  
Lubricating Film ◽  
Fluid Field ◽  
Grinding Fluid ◽  
Smooth Model ◽  
Area Increase

Relative motion between grinding wheel and workpiece makes the lubricant film pressure formed by grinding fluid in the grinding area increase, consequently, dynamic pressure lubrication forms. The grinding fluid flow field mathematical model in smooth grinding area is established based on lubrication theory. The dynamic pressure of grinding fluid field, flow velocity and carrying capacity of lubricating film are calculated by the numerical analysis method. An analysis of effect of grinding fluid hydrodynamic on the total lifting force is performed, and the results are obtained.

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