Nonlinear dynamic behaviour of guy cables in turbulent winds

2001 ◽  
Vol 28 (1) ◽  
pp. 98-110 ◽  
Author(s):  
Bruce F Sparling ◽  
Alan G Davenport
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Horizontal Displacement ◽  
Wind Loading ◽  
Second Phase ◽  
Nonlinear Coupling ◽  
Wide Range ◽  
Cable Vibrations

Large amplitude cable vibrations are difficult to predict using linear theory due to the presence of sag in the suspended profile. A numerical study was therefore undertaken to investigate the dynamic behaviour of inclined cables excited by imposed displacements. To model the nonlinear nature of cable response, a time domain finite element approach was adopted using nonlinear catenary cable elements. Two types of horizontal displacement patterns were enforced at the upper end of the guy. In the first phase of the study, harmonic displacement histories with a wide range of forcing frequencies were considered. In the second phase, random enforced displacements were used to simulate the motion of a guyed mast in gusty winds. The influence of aerodynamic drag and damping forces was investigated by performing analyses under still air, steady wind, and turbulent wind conditions. It was found that nonlinear coupling of related harmonic response components was significant at certain critical frequencies, particular when the excitation was harmonic and acted in the plane of the guy. Positive aerodynamic damping was shown to effectively suppress resonant and nonlinear coupling response.Key words: cables, structural dynamics, wind loading, finite element method, nonlinear analysis, guyed towers.

scholarly journals Convergence of the finite element method and the semi-analytical finite element method for prismatic bodies with variable physical and geometric parameters

2021 ◽  
pp. 92-104
Author(s):  
Viktor Bazhenov ◽  
Maksym Horbach ◽  
Ivan Martyniuk ◽  
Oleksandr Maksimyuk
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Study ◽  
Test Problems ◽  
Test Cases ◽  
Approximation Accuracy ◽  
Convergence Of Solutions ◽  
Wide Range ◽  
Prismatic Bodies ◽  
Element Method

In this paper, a numerical study of the convergence of solutions obtained on the basis of the developed approach [1, 3, 4, 5] is carried out. A wide range of test problems for bodies with smoothly and abruptly varying physical and geometric characteristics in elastic and elastic-plastic formulation are considered. The approach developed within the framework of the semi-analytical method to study the stress-strain state of inhomogeneous curvilinear prismatic bodies, taking into account physical and geometric nonlinearity, requires substantiation of its effectiveness in relation to the traditional FEM and confirmation of the reliability of the results obtained on its basis. The main indicators that allow comparing the SAFEM and FEM include the rate of convergence of solutions with an increase in the number of unknowns and the amount of charges associated with solving linear and nonlinear equations. For the considered class of problems, the convergence is determined by such factors as the nature of the change along Z3’ of the geometric and mechanical parameters of the object. The uneven distribution of mechanical characteristics is associated with the presence of the initial heterogeneity of the material, the development of plastic deformations, and the dependence of material properties on temperature. The same factors also affect the convergence of the iterative process, since the conditionality of the SAFEM matrix depends on them. In order to determine the area of effective application of the SAFEM, a wide range of test cases are considered. In all cases, the semi-analytic finite element method is not inferior in approximation accuracy, and in some problems it is 1.5-2 times superior to the traditional method of scheduling elements. finite element method.

scholarly journals Numerical Study of the Active Tendon Control of a Cable-Stayed Bridge in a Construction Phase

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
M. H. El Ouni ◽  
N. Ben Kahla
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Force Feedback ◽  
Numerical Study ◽  
Element Model ◽  
Small Scale ◽  
Cable Stayed Bridge ◽  
Displacement Sensors ◽  
Out Of Plane ◽  
Cable Vibrations

This paper investigates numerically the active tendon control of a cable-stayed bridge in a construction phase. A linear Finite Element model of small scale mock-up of the bridge is first presented. Active damping is added to the structure by using pairs of collocated force actuator-displacement sensors located on each active cable and decentralized first order positive position feedback (PPF) or direct velocity feedback (DVF). A comparison between these two compensators showed that each one has good performance for some modes and performs inadequately with the other modes. A decentralized parallel PPF-DVF is proposed to get the better of the two compensators. The proposed strategy is then compared to the one using decentralized integral force feedback (IFF) and showed better performance. The Finite Element model of the bridge is coupled with a nonlinear cable taking into account sag effect, general support movements, and quadratic and cubic nonlinear couplings between in-plane and out-of-plane motions. Finally, the proposed strategy is used to control both deck and cable vibrations induced by parametric excitation. Both cable and deck vibrations are attractively damped.

Generalized Model for the Approximation of Coupled Acousto-Mechanical Natural Frequencies in High-Pressure Centrifugal Compressors

2020 ◽  
Author(s):  
Christoph Rocky Heinrich ◽  
Arnold Kühhorn ◽  
Klaus Steff ◽  
Nico Petry
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Natural Frequencies ◽  
Numerical Study ◽  
Operating Conditions ◽  
Centrifugal Compressors ◽  
Element Analysis ◽  
Generalized Model ◽  
Wide Range ◽  
The Impact

Abstract The oil and gas, chemical, and process industries employ centrifugal compressors for a wide range of applications. Due to this, the conditions under which centrifugal compressors have to operate, vary significantly from case to case. Gas pipeline compressors, for example, may feature discharge pressures well over 100 bar. During the last decades, comprehensive research was conducted on the impact of high pressure operating conditions on the vibrational behavior of centrifugal compressors. Nowadays, it is well-known that an increase in gas pressure levels leads to a more pronounced interaction between the side cavities and the impeller, which results in a frequency shift of the acoustic and structural modes. For the safe operation of compressors, it is necessary to predict these coupled natural frequencies accurately. The state-of-the-art approach to achieve this objective is the finite element method. While this technique provides high-quality results, it incurs high computational costs and is, therefore, time-consuming. The authors of the current paper propose a generalized model to overcome this challenge. It uses the uncoupled modes of the impeller and side cavities in a modal superposition to approximate the coupled system's natural frequencies. In this way, the intended design geometries are considered while reducing the computational effort significantly. In a numerical study, the generalized model is applied to different systems of increasing complexity, and the results are compared to a finite element analysis. Finally, the paper concludes with a discussion of the limitations and benefits of all employed numerical methods.

A numerical study on the sound transmission loss of HST aluminum extruded panel

2020 ◽  
Vol 68 (5) ◽  
pp. 367-377
Author(s):  
Xu Zheng ◽  
Peilin Ruan ◽  
Le Luo ◽  
Yi Qiu ◽  
Zhiyong Hao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Performance Optimization ◽  
High Speed ◽  
Transmission Loss ◽  
Numerical Study ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Wide Range ◽  
Element Method

Aluminum is a light, strong, and corrosion-resistant material. Its extruded form, the aluminum extruded panel, consists of two aluminum plates with truss core, which can be applied in a wide range of engineering areas. In this work, the structure-acoustic coupling finite element method (FEM) is employed to analyze the sound transmission through high-speed train (HST) aluminum extruded panels. The automatically matched layer (AML) is used to simulate the non-reflective boundary condition. It is found that the predicted sound transmission loss (STL) is in good agreement with the experimental results and the prediction accuracy of the finite element method can be further verified. Based on this proposed method, a parametric study is carried out to investigate how the structure parameters affect the STL. The results suggest that the rib angle exhibits a greater effect on STL in the above-middle frequency area where the modal density is high. The increase in the height between the panels will lead to a higher STL overall value of the aluminum extruded panel and make the STL dips move toward higher frequencies, while the increase of the rib thickness will drive the STL dips to an opposite direction. Finally, the STLs of the aluminum extruded panel in different regions of the train body are comprehensively analyzed. The highest overall value of STL is found in the flat-top region, whereas the lowest value appears in the curve-top region. Overall, the results in this article can provide valuable implications for the noise performance optimization of HST.

ELASTIC BUCKLING OF THIN-WALLED CYLINDERS UNDER WIND LOADING: AN EXPERIMENTAL STUDY

2009 ◽  
Vol 09 (01) ◽  
pp. 1-10 ◽  
Author(s):  
MARTIN PIRCHER ◽  
BERNHARD LECHNER ◽  
HELMUT TRUTNOVSKY
Keyword(s):  
Experimental Study ◽  
Failure Modes ◽  
Numerical Study ◽  
Wind Loading ◽  
Small Scale ◽  
Radial Compression ◽  
Buckling Mode ◽  
Cylindrical Structures ◽  
Wide Range ◽  
Thin Walled

Thin-walled cylindrical structures have been found to display three distinctly different stability failure modes under wind loading, depending on their geometric and material properties. In low cylinders the radial compression at the meridian facing the wind causes a buckling mode similar to that for cylinders under constant radial compression, while very long cylinders display a failure mode characterized by buckling in the lower third of the structure at the side which faces away from the wind. The failure of medium height cylinders is characterized by a number of horizontal, ripple-like buckles in an area around the upper half of the meridian which faces the wind. In an ongoing experimental study, a series of small-scale specimens with a wide range of geometric parameters is being tested in a wind tunnel. To the knowledge of the authors, this is the first time that the particular buckling mode for medium height cylinders has been documented in an experiment. The present paper gives a summary of the results gained from this study so far and compares them qualitatively to those of a previous numerical study.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

Bond Thickness Effects upon Dynamic Behaviour in Adhesive Joints

2010 ◽  
Vol 97-101 ◽  
pp. 3920-3923 ◽  
Author(s):  
Xiao Cong He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Behaviour ◽  
Adhesive Layer ◽  
Adhesive Joints ◽  
Response Functions ◽  
Frequency Range ◽  
Element Analysis ◽  
Cantilevered Beam ◽  
Different Thickness

The influence of adhesive layer thickness on the dynamic behaviour of the single-lap adhesive joints is investigated in this paper. The ABAQUS finite element analysis (FEA) software was used to predict the frequency response functions (FRFs) of the single-lap adhesive joints of different thickness of the adhesive layer. As a reference, the FRFs of a cantilevered beam without joint were investigated as well. It is clear that the FRFs of the four beams are close to each other within the frequency range 0~1000 Hz. It is also found that the composite damping of the single-lap adhesive joint increases as the thickness of the adhesive layer increases.

scholarly journals Strain Sensor via Wood Anomalies in 2D Dielectric Array

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1022
Author(s):  
Rashid G. Bikbaev ◽  
Ivan V. Timofeev ◽  
Vasiliy F. Shabanov
Keyword(s):  
Higher Plants ◽  
Numerical Study ◽  
Reciprocal Lattice ◽  
Strain Sensing ◽  
Photonic Materials ◽  
Sensing Applications ◽  
Wide Range ◽  
Sensor Structure ◽  
Optical Behavior ◽  
Chlorophyll Absorption

Optical sensing is one of many promising applications for all-dielectric photonic materials. Herein, we present an analytical and numerical study on the strain-responsive spectral properties of a bioinspired sensor. The sensor structure contains a two-dimensional periodic array of dielectric nanodisks to mimic the optical behavior of grana lamellae inside chloroplasts. To accumulate a noticeable response, we exploit the collective optical mode in grana ensemble. In higher plants, such a mode appears as Wood’s anomaly near the chlorophyll absorption line to control the photosynthesis rate. The resonance is shown persistent against moderate biological disorder and deformation. Under the stretching or compression of a symmetric structure, the mode splits into a couple of polarized modes. The frequency difference is accurately detected. It depends on the stretch coefficient almost linearly providing easy calibration of the strain-sensing device. The sensitivity of the considered structure remains at 5 nm/% in a wide range of strain. The influence of the stretching coefficient on the length of the reciprocal lattice vectors, as well as on the angle between them, is taken into account. This adaptive phenomenon is suggested for sensing applications in biomimetic optical nanomaterials.

Sign in / Sign up

Export Citation Format

Share Document