Yanfei Chen

Free vibration analysis of rotating tapered Timoshenko beams via variational iteration method

Accurate determination of natural frequencies and mode shapes of the rotating tapered Timoshenko beam is important in engineering practice. This paper re-examines the free vibration of rotating tapered Timoshenko beams using the technique of variational iteration, which is relatively new and is capable of providing accurate solutions for eigenvalue problems in a quite easy way. Natural frequencies and mode shapes for rotating tapered Timoshenko beams with linearly varying height as well as linearly varying height and width are investigated via two numerical examples, and solutions are compared with results published in literature where available. Since the method constitutes a numerical procedure, the convergence of solutions which is important for practical implementation is evaluated as well, where efficiency and accuracy of variational iteration method in solving high order eigenvalue problems are demonstrated.

Flapwise bending vibration of rotating tapered beams using variational iteration method

Although flapwise bending vibration of rotating tapered beams has been extensively studied since the 1970s, most of these studies were based on approximations with varying degrees of accuracy and complexity. The flapwise bending vibration of rotating tapered beams is re-examined in this paper using the technique of variational iteration, which is relatively new and capable of providing accurate results for eigenvalue problems with good convergence. Natural frequencies and mode shapes of rotating beams are extracted for various rotational speeds and taper ratios, and solutions are compared with results published in the literature where available.

Strain Prediction for X80 Steel Pipeline Subjected to Strike-Slip Fault Under Compression Combined With Bending

Strike-slip fault is one main kind of PGD faced by long distance gas pipelines. Based on non-linear finite element method, a numerical model for buried pipeline under strike-slip fault was proposed. The model was proven to be reasonable by comparing the numerical results with previous researcher’s experiment results. By using the FE model, peak compressive strain of X80 steel pipeline subjected to strike-slip fault under compression combined with bending was studied. The sensitivities of the diameter, wall thickness, soil rigidity, fault displacement and crossing angle on the peak compressive strain of the pipeline are examined in detail. Furthermore, based on numerous numerical results, a regression equation for predicting peak compressive strain of X80 steel pipeline is proposed. The applicable range of the formula is given. 15 true design cases in the Second West to East pipeline Project in China were investigated to demonstrate the accuracy and applicability of the proposed methodology by comparing the predicting peak compressive strain results with FEM results. The proposed method can be referred in the strain-based and reliability-based design for X80 steel pipelines subjected to strike-slip fault.Copyright