Three-Dimensional Dynamics of Towed Underslung Systems Using Geometrically Exact Beam Theory

AIAA Journal ◽  
2021 ◽  
pp. 1-14
Author(s):  
Abhinav Ravindra Dehadrai ◽  
Ishan Sharma ◽  
Shakti S. Gupta
Keyword(s):  
Three Dimensional ◽  
Beam Theory ◽  
Geometrically Exact Beam ◽  
Geometrically Exact Beam Theory

scholarly journals High-Efficiency Dynamic Modeling of a Helical Spring Element Based on the Geometrically Exact Beam Theory

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jian Zhang ◽  
Zhaohui Qi ◽  
Gang Wang ◽  
Shudong Guo
Keyword(s):  
High Efficiency ◽  
Curvature Vector ◽  
Polar Angle ◽  
Beam Theory ◽  
High Frequency Oscillation ◽  
Helical Spring ◽  
Static Stiffness ◽  
Spring Element ◽  
Geometrically Exact Beam ◽  
Geometrically Exact Beam Theory

This paper presents a modeling study of the dynamics of a helical spring element with variable pitch and radius considering both the static stiffness and dynamic response by using the geometrically exact beam theory. The geometrically exact beam theory based on the Euler–Bernoulli beam hypothesis is described, of which the shear deformations are ignored. Unlike the traditional spliced curved beam element method, the helical spring element is described with curvature vector and axial strain by establishing and spline-interpolating a function of the radius, the height, the polar angle, and the torsion angle of the whole spring. In addition, a model smoothing method is developed and applied in the numerical analysis to filter the high-frequency oscillation component of the flexible multibody systems, so as to correct the system dynamic equations and improve the calculation efficiency when solving the static equilibrium of the spring. This study also carries out five numerical trials to validate the above dynamic procedure of the helical spring element. The example of the spring static stiffness design shows that the proposed helical spring procedure enables one to deal with practical engineering applications.

Ultimate strength of steel beam-columns under axial compression

2017 ◽  
Vol 231 (4) ◽  
pp. 828-843
Author(s):  
Zhongwei Li ◽  
Mayuresh Patil ◽  
Xiaochuan Yu
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Beam Theory ◽  
Computer Code ◽  
Offshore Structures ◽  
Element Analysis ◽  
Beam Columns ◽  
Geometrically Exact Beam ◽  
Steel Panels ◽  
Geometrically Exact Beam Theory

This article presents a semi-analytical method to calculate the ultimate strength of inelastic beam-columns with I-shaped cross section using geometrically exact beam theory. A computer code based on this method has been applied to beam-columns under axial compression. The results agree with nonlinear finite element analysis. Compared with previous step-by-step integration approach, this new method is more efficient and can be extended to multi-span beam-columns and other load combinations including lateral pressure. The presented beam-column model is ideally suited for ultimate strength prediction of stiffened steel panels of ships and offshore structures.

Structural Dynamic Analysis of a Tidal Current Turbine Using Geometrically Exact Beam Theory

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Qi Wang ◽  
Pengkun Zhang ◽  
Ye Li
Keyword(s):  
Dynamic Analysis ◽  
Tidal Current ◽  
Dynamic Performance ◽  
Beam Theory ◽  
Structural Dynamic ◽  
Discrete Vortex ◽  
Geometrically Exact Beam ◽  
Tidal Current Turbine ◽  
Geometrically Exact Beam Theory ◽  
Current Turbine

This paper presents a numerical study of the dynamic performance of a vertical axis tidal current turbine. First, we introduce the geometrically exact beam theory along with its numerical implementation the geometric exact beam theory (GEBT), which are used for structural modeling. We also briefly review the variational-asymptotic beam sectional analysis (VABS) theory and discrete vortex method with free-wake structure (DVM-UBC), which provide the one-dimensional (1D) constitutive model for the beam structures and the hydrodynamic forces, respectively. Then, we validate the current model with results obtained by ANSYS using three-dimensional (3D) solid elements and good agreements are observed. We investigate the dynamic performance of the tidal current turbine including modal behavior and transient dynamic performance under hydrodynamic loads. Finally, based on the results in the global dynamic analysis, we study the local stress distributions at the joint between blade and arm by VABS. It is concluded that the proposed analysis method is accurate and efficient for tidal current turbine and has a potential for future applications to those made of composite materials.

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