A model of the time-harmonic torsional response of piled plates using an IBEM-FEM coupling

2021 ◽  
Vol 125 ◽  
pp. 241-249
Author(s):  
Josué Labaki ◽  
Pérsio L. A Barros ◽  
Euclides Mesquita
Keyword(s):  
Torsional Response ◽  
Time Harmonic

Dynamic Torsional Response of a Pile Partially Embedded in Saturated Soil

2014 ◽  
Vol 509 ◽  
pp. 27-33
Author(s):  
Rui Fu Qin ◽  
Zhi Qing Zhang ◽  
Rong Fa Chen
Keyword(s):  
Inverse Fourier Transform ◽  
Vertical Direction ◽  
Sine Wave ◽  
Saturated Soil ◽  
Soil System ◽  
Impedance Function ◽  
Torsional Response ◽  
Time Harmonic ◽  
Velocity Response ◽  
The Time Domain

The dynamic response of an elastic supporting pile partially embedded in a saturated soil and subjected to a time-harmonic torsional loading is investigated. At first, the pile is divided into two parts along the vertical direction, pile part above the soil and pile part embedded in the soil. Then, based on boundary and continuity conditions of the pile-soil system, the torsional impedance at the top end of the pile part embedded in the soil is obtained. By utilizing the transfer technique of impedance function, the admittance function of the pile top is defined in the frequency domain. By virtue of inverse Fourier transform and convolution theorem, a semi-analytical solution for the velocity response of a pile subjected to a semi-sine wave exciting torque is obtained in the time domain. Finally, selected numerical results are obtained to analyze the influence of main parameters on the torsional vibration characteristics of the pile.

Influence of Prestressing on Torsional Response of Concrete Beams

PCI Journal ◽  
1978 ◽  
Vol 23 (3) ◽  
pp. 54-73 ◽  
Author(s):  
Denis Mitchell ◽  
Michael P. Collins
Keyword(s):  
Concrete Beams ◽  
Torsional Response

Calculating the response of waveguides to base excitation using the wave and finite element method

2021 ◽  
pp. 107754632098131
Author(s):  
Jamil Renno ◽  
Sadok Sassi ◽  
Wael I Alnahhal
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Transfer Functions ◽  
Travelling Waves ◽  
Model Free ◽  
Time Harmonic ◽  
Element Approach ◽  
Response Transfer ◽  
Free Wave Propagation ◽  
Element Method

The prediction of the response of waveguides to time-harmonic base excitations has many applications in mechanical, aerospace and civil engineering. The response to base excitations can be obtained analytically for simple waveguides only. For general waveguides, the response to time-harmonic base excitations can be obtained using the finite element method. In this study, we present a wave and finite element approach to calculate the response of waveguides to time-harmonic base excitations. The wave and finite element method is used to model free wave propagation in the waveguide, and these characteristics are then used to find the amplitude of excited waves in the waveguide. Reflection matrices at the boundaries of the waveguide are then used to find the amplitude of the travelling waves in the waveguide and subsequently the response of the waveguide. This includes the displacement and stress frequency response transfer functions. Numerical examples are presented to demonstrate the approach and to discuss the numerical efficiency of the proposed method.

The inverse elastic scattering by an impenetrable obstacle and a crack

2020 ◽  
Author(s):  
Jianli Xiang ◽  
Guozheng Yan
Keyword(s):  
Mixed Type ◽  
Scattering Problem ◽  
Inverse Scattering Problem ◽  
Field Operator ◽  
Integral Equation Method ◽  
Factorization Method ◽  
Boundary Integral ◽  
Far Field ◽  
Direct Scattering ◽  
Time Harmonic

Abstract This paper is concerned with the inverse scattering problem of time-harmonic elastic waves by a mixed-type scatterer, which is given as the union of an impenetrable obstacle and a crack. We develop the modified factorization method to determine the shape of the mixed-type scatterer from the far field data. However, the factorization of the far field operator $F$ is related to the boundary integral matrix operator $A$, which is obtained in the study of the direct scattering problem. So, in the first part, we show the well posedness of the direct scattering problem by the boundary integral equation method. Some numerical examples are presented at the end of the paper to demonstrate the feasibility and effectiveness of the inverse algorithm.

scholarly journals Analysis of Flexural Vibrations of a Piezoelectric Semiconductor Nanoplate Driven by a Time-Harmonic Force

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3926
Author(s):  
Mengen Li ◽  
Qiaoyun Zhang ◽  
Bingbing Wang ◽  
Minghao Zhao
Keyword(s):  
Electron Concentration ◽  
Smart Devices ◽  
Harmonic Force ◽  
Plate Structures ◽  
Piezoelectric Semiconductor ◽  
Initial Electron ◽  
Time Harmonic ◽  
Semiconductor Plate ◽  
Flexural Vibrations ◽  
Piezoelectric Semiconductors

The performance of devices fabricated from piezoelectric semiconductors, such as sensors and actuators in microelectromechanical systems, is superior; furthermore, plate structures are the core components of these smart devices. It is thus important to analyze the electromechanical coupling properties of piezoelectric semiconductor nanoplates. We established a nanoplate model for the piezoelectric semiconductor plate structure by extending the first-order shear deformation theory. The flexural vibrations of nanoplates subjected to a transversely time-harmonic force were investigated. The vibrational modes and natural frequencies were obtained by using the matrix eigenvalue solver in COMSOL Multiphysics 5.3a, and the convergence analysis was carried out to guarantee accurate results. In numerical cases, the tuning effect of the initial electron concentration on mechanics and electric properties is deeply discussed. The numerical results show that the initial electron concentration greatly affects the natural frequency and electromechanical fields of piezoelectric semiconductors, and a high initial electron concentration can reduce the electromechanical fields and the stiffness of piezoelectric semiconductors due to the electron screening effect. We analyzed the flexural vibration of typical piezoelectric semiconductor plate structures, which provide theoretical guidance for the development of new piezotronic devices.

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