Linear Vibration Analysis of Shells Using a Seven-Parameter Spectral/hp Finite Element Model

In this paper, a seven-parameter spectral/hp finite element model to obtain natural frequencies in shell type structures is presented. This model accounts for constant and variable thickness of shell structures. The finite element model is based on a Higher-order Shear Deformation Theory, and the equations of motion are obtained by means of Hamilton’s principle. Analysis is performed for isotropic linear elastic shells. A validation of the formulation is made by comparing the present results with those reported in the literature and with simulations in the commercial code ANSYS. Finally, results for shell like structures with variable thickness are presented, and their behavior for different ratios r/h and L/r is studied.

A study of azimuthal electromagnetic wave LWD based on self-adaptive hp finite element method

Azimuthal electromagnetic wave logging-while-drilling (LWD) technology can detect weak electromagnetic wave signal and realize real-time resistivity imaging. It has great values to reduce drilling cost and increase drilling rate. In this paper, self-adaptive hp finite element method (FEM) has been used to study the azimuthal resistivity LWD responses in different conditions. Numerical simulation results show that amplitude attenuation and phase shift of directional electromagnetic wave signals are closely related to induced magnetic field and azimuthal angle. The peak value and polarity of geological guidance signals can be used to distinguish reservoir interface and achieve real-time geosteering drilling. Numerical simulation results also show the accuracy of the self-adaptive hp FEM and provide physical interpretation of peak value and polarity of the geological guidance signals.