Dispersion analysis of magneto-electro elastic plate of arbitrary cross-sections immersed in fluid

2018 ◽  
Vol 15 (1) ◽  
pp. 130-147 ◽  
Author(s):  
Rajendran Selvamani
Keyword(s):  
Boundary Conditions ◽  
Cross Sections ◽  
Elastic Plate ◽  
Electric Potential ◽  
Composite Plates ◽  
Dispersion Analysis ◽  
Hoop Strain ◽  
Cross Sectional ◽  
Content Type ◽  
Longitudinal Modes

Purpose This study aims to construct a mathematical model to study the dispersion analysis of magneto-electro elastic plate of arbitrary cross sections immersed in fluid by using the Fourier expansion collocation method (FECM). Design/methodology/approach The analytical formulation of the problem is designed and developed using three-dimensional linear elasticity theories. As the inner and outer boundaries of the arbitrary cross-sectional plate are irregular, the frequency equations are obtained from the arbitrary cross-sectional boundary conditions by using FECM. The roots of the frequency equation are obtained using the secant method, which is applicable for complex solutions. Findings The computed physical quantities such as radial stress, hoop strain, non-dimensional frequency, magnetic potential and electric potential are plotted in the form of dispersion curves, and their characteristics are discussed. To study the convergence, the non-dimensional wave numbers of longitudinal modes of arbitrary (elliptic and cardioid) cross-sectional plates are obtained using FECM and finite element method and are presented in a tabular form. This result can be applied for optimum design of composite plates with arbitrary cross sections. Originality/value This paper contributes the analytical model for the role of arbitrary cross-sectional boundary conditions and impact of fluid loading on the dispersion analysis of magneto-electro elastic plate. From the graphical patterns of the structure, the effects of stress, strain, magnetic, electric potential and the surrounding fluid on the various considered wave characteristics are more significant and dominant in the cardioid cross sections. Also, the aspect ratio (a/b) and the geometry parameters of elliptic and cardioids cross sections are significant to the industry or other fields that require more flexibility in design of materials with arbitrary cross sections.

Wave propagation in electro‐magneto‐elastic solid plate of polygonal cross‐sections

2013 ◽  
Vol 9 (1) ◽  
pp. 23-48 ◽  
Author(s):  
P. Ponnusamy
Keyword(s):  
Wave Propagation ◽  
Boundary Conditions ◽  
Cross Sections ◽  
Elastic Plate ◽  
Elastic Solid ◽  
Theory Of Elasticity ◽  
Elastic Plates ◽  
Cross Sectional ◽  
Content Type ◽  
Solid Plate

PurposeThis paper aims to describe the method for solving vibration problem of electro‐magneto‐elastic plate of polygonal (triangle, square, pentagon and hexagon) cross‐sections using Fourier expansion collocation method (FECM).Design/methodology/approachA mathematical model is developed to study the wave propagation in an electro‐magneto‐elastic plate of polygonal cross‐sections using the theory of elasticity. The frequency equations are obtained from the arbitrary cross‐sectional boundary conditions, since the boundary is irregular in shape; it is difficult to satisfy the boundary conditions along the surface of the plate directly. Hence, the FECM is applied along the boundary to satisfy the boundary conditions. The roots of the frequency equations are obtained by using the secant method, applicable for complex roots.FindingsFrom the literature survey, it is clear that the free vibration of electro‐magneto‐elastic plate of polygonal cross‐sections have not been analyzed by any of the researchers, also the previous investigations in the vibration problems of electro‐magneto‐elastic plates are based on the traditional circular cross‐sections only. So, in this paper, the wave propagation in electro‐magneto‐elastic plate of polygonal cross‐sections is studied using the FECM. The computed non‐dimensional frequencies are plotted in the form of dispersion curves and their characteristics are discussed.Originality/valueThe researchers have discussed the circular, rectangular, triangular and square cross‐sectional plates by the boundary conditions. In this problem, the author studied the vibrations of polygonal (triangle, square, pentagon and hexagon) cross‐sectional plates using the geometrical relation which is applicable to all the cross‐sections. The problem may be extended to any kinds of cross‐sections by using the proper geometrical relations.

Dynamic Stability of Slender Concrete-Filled Steel Tubular Columns with General Supports

2019 ◽  
Vol 19 (04) ◽  
pp. 1950045
Author(s):  
Youqin Huang ◽  
Jiyang Fu ◽  
Di Wu ◽  
Airong Liu ◽  
Wei Gao ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Dynamic Stability ◽  
Cross Sections ◽  
Dynamic Instability ◽  
Static Stability ◽  
Constant Component ◽  
Cross Sectional ◽  
Tubular Columns ◽  
New Findings ◽  
Cfst Columns

The static stability of slender concrete-filled steel tubular (CFST) columns has been explored thoroughly while few researches have been carried out on the dynamic stability of CFST columns even if all applied loadings are naturally time-dependent. This paper presents an analytical procedure for evaluating the dynamic stability of CFST columns of various composite cross-sections under general boundary conditions. This paper is featured by the following facts: (1) proportional damping is considered in derivation of the governing equations on the lateral parametric vibration of the CFST columns subject to axial excitation; (2) Bolotin’s method is used to determine the boundaries of the regions of dynamic instability for the CFST columns with general supports; (3) the relationship of static and dynamic stability, and the effects of boundary conditions and cross-sectional forms are uncovered. New findings of this investigation are (1) larger amplitude or constant component of excitation make it easier for the dynamic instabilities of the CFST columns to occur, while increasing the constant component of excitation reduces the critical value of frequency ratio for the dynamic instability to occur; (2) the dynamic stability analysis can determine the critical loads for both the static and dynamic instability of CFST columns, and the critical instability load decreases with increasing disturbance on the static load; (3) under the same consumptions of steel and concrete, the square columns have better performance of dynamic stability than the circular columns, but there is no definite conclusion on the effect of hollow size on the dynamic stability of double-skin columns.

Analytical solutions of thermo-piezoelectric interactions in a solid fiber of polygonal cross-sections immersed in fluid

2018 ◽  
Vol 14 (3) ◽  
pp. 431-456
Author(s):  
Rajendran Selvamani
Keyword(s):  
Mathematical Model ◽  
Phase Velocity ◽  
Cross Sections ◽  
Analytical Solutions ◽  
Fourier Expansion ◽  
Transversely Isotropic ◽  
Cross Sectional ◽  
Content Type ◽  
Phase Velocity And Attenuation ◽  
Frequency Phase

Purpose The purpose of this paper is to study the analytical solutions of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid using the Fourier expansion collocation method. Design/methodology/approach A mathematical model is developed for the analytical study on a transversely isotropic thermo-piezoelectric polygonal cross-sectional fiber immersed in fluid using a linear form of three-dimensional piezothermoelasticity theories. After developing the formal solution of the mathematical model consisting of partial differential equations, the frequency equations have been analyzed numerically by using the Fourier expansion collocation method (FECM) at the irregular boundary surfaces of the polygonal cross-sectional fiber. The roots of the frequency equation are obtained by using the secant method, applicable for complex roots. Findings From the literature survey, it is evident that the analytical formulation of thermo-piezoelectric interactions in a polygonal cross-sectional fiber contact with fluid is not discussed by any researchers. Also, in this study, a polygonal cross-section is used instead of the traditional circular cross-sections. So, the analytical solutions of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid are studied using the FECM. The dispersion curves for non-dimensional frequency, phase velocity and attenuation coefficient are presented graphically for lead zirconate titanate (PZT-5A) material. The present analytical method obtained by the FECM is compared with the finite element method which shows a good agreement with present study. Originality/value This paper contributes the analytical model to find the solution of transversely isotropic thermo-piezoelectric interactions in a polygonal cross-sectional fiber immersed in fluid. The dispersion curves of the non-dimensional frequency, phase velocity and attenuation coefficient are more prominent in flexural modes. Also, the surrounding fluid on the various considered wave characteristics is more significant and dispersive in the hexagonal cross-sections. The aspect ratio (a/b) of polygonal cross-sections is critical to industry or other fields which require more flexibility in design of materials with arbitrary cross-sections.

Performance investigation of micro-pocketed textured pad thrust bearing

2018 ◽  
Vol 70 (8) ◽  
pp. 1388-1395 ◽  
Author(s):  
Shipra Aggarwal ◽  
R.K. Pandey
Keyword(s):  
Coefficient Of Friction ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Load Carrying Capacity ◽  
Temperature Relation ◽  
Cross Sectional ◽  
Content Type ◽  
Load Carrying ◽  
Coupled Solution

Purpose The purpose of this paper is to conceive a new surface texture incorporating a tiny shape among the micro-pockets (with circular, rectangular, trapezoidal and triangular cross-sections) and dimples (cylindrical, hemispherical and ellipsoidal) for exploring to enhance the maximum possible performance behaviors of sector shape pad thrust bearing. Design/methodology/approach Numerical simulation of hydrodynamically lubricated sector shape textured pad thrust bearing has been presented incorporating thermal and cavitation effects. The coupled solution of governing equations (Reynolds equation, film thickness expression, viscosity–temperature relation, energy equation and Laplace equation) has been achieved using finite difference method and Gauss–Seidel iterative scheme. Findings With new textured pads, higher load-carrying capacity and lower coefficient of friction are obtained in comparison to plain sector shape pad. Texture pattern comprising square cross-sectional pockets yields higher load-carrying capacity and lower coefficient of friction in comparison to other cross-sectional shapes (circular, trapezoidal and triangular) of pockets considered herein. Originality/value This study reports a new texture, which involves micro-pockets of square cross-sectional shapes to improve the performance behavior of sector shape pad thrust bearing. About 75 per cent increase in load carrying capacity and 42 per cent reduction in coefficient of friction have been achieved with pad having new texture in comparison to conventional pad.

Rheological and printable behavior of resin – class materials for 3D printing applications

2019 ◽  
Vol 25 (5) ◽  
pp. 801-808
Author(s):  
Jianzhong Shang ◽  
Xin Li ◽  
Zhuo Wang ◽  
Rong Wang ◽  
Hong Zhu
Keyword(s):  
Process Parameters ◽  
Cross Sections ◽  
Rheological Behavior ◽  
Dimensional Accuracy ◽  
Cross Sectional ◽  
Content Type ◽  
Nozzle Height ◽  
Uniform Wall ◽  
The Cross ◽  
Printing Parameters

Purpose This study aims to investigate rheological and extrusion behavior of thermosetting epoxy resins, which to find the universal property and printing parameters for extrusion-based rapid prototyping applications. Design/methodology/approach The thickener proportion greatly influences its viscosity and rheological behavior and therefore plays an important role in the shape of the cross-section of the extrudate. Findings A pseudoplastic (shear-thinning) is a basic requirement for obtaining extruded lines with plump cross-sections. In addition to the effects of the rheological behavior of the composite, shape maintenance and its wettability on the substrate, the cross-sectional geometry of the extrudate is also strongly affected by printing process parameters including the extrusion nozzle height, nozzle moving speed, extrusion rate and critical nozzle height. Proper combinations of these process parameters are necessary to obtain single-line extrudates with plump cross-sections and 3-D objects with dimensional accuracy, uniform wall thickness, good wall uprightness and no wall slumping. Formulas and procedures for determining these extrusion parameters are proposed and demonstrated in experiments. Originality/value The results obtained have been explained in terms of the interactions among the rheological properties of the composite, the shear rate imposed on the composite during extrusion, the wettability of the composite on the substrate and the shape maintenance of the composite during extrusion.

scholarly journals Multi-objective NSGA-II based shape optimisation of the cross-sectional shape of passively cooled heat sinks

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mani Sekaran Santhanakrishnan ◽  
Tim Tilford ◽  
Chris Bailey
Keyword(s):  
Cross Sections ◽  
Heat Sink ◽  
Shape Optimisation ◽  
Nsga Ii ◽  
Cross Sectional ◽  
Cooling Effectiveness ◽  
Content Type ◽  
Multi Objective ◽  
Pin Fin ◽  
Sectional Shape

Purpose The purpose of the study is to optimise the cross-sectional shape of passively cooled horizontally mounted pin-fin heat sink for higher cooling performance and lower material usage. Design/methodology/approach Multi-objective shape optimisation technique is used to design the heat sink fins. Non-dominated sorting genetic algorithm (NSGA-II) is combined with a geometric module to develop the shape optimiser. High-fidelity computational fluid dynamics (CFD) is used to evaluate the design objectives. Separate optimisations are carried out to design the shape of bottom row fins and middle row fins of a pin-fin heat sink. Finally, a computational validation was conducted by generating a three-dimensional pin-fin heat sink using optimised fin cross sections and comparing its performance against the circular pin-fin heat sink with the same inter-fin spacing value. Findings Heat sink with optimised fin cross sections has 1.6% higher cooling effectiveness than circular pin-fin heat sink of same material volume, and has 10.3% higher cooling effectiveness than the pin-fin heat sink of same characteristics fin dimension. The special geometric features of optimised fins that resulted in superior performance are highlighted. Further, Pareto-optimal fronts for this multi-objective optimisation problem are obtained for different fin design scenarios. Originality/value For the first time, passively cooled heat sink’s cross-sectional shapes are optimised for different spatial arrangements, using NSGA-II-based shape optimiser, which makes use of CFD solver to evaluate the design objectives. The optimised, high-performance shapes will find direct application to cool power electronic equipment.

Examination of the effect of fire retardant materials on timber

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Eva Lubloy ◽  
Lajos Gábor Takács ◽  
David Istvan Enczel ◽  
Zsolt Cimer
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Fire Retardant ◽  
Fire Retardants ◽  
Cross Sectional ◽  
Content Type ◽  
Beneficial Effects ◽  
Burn Rate ◽  
In Fire ◽  
Core Problem

PurposeThe fire safety of structures is an existing and important design aspect, which is assured by strict regulations. As a means to adhere to the strict requirements, fire protection has become a core problem. It is particularly difficult to comply with these regulations in the case of timber, which is a combustible material. These problems could be solved by enveloping the wood in fire retardant materials. MSZ EN 1995-1-2 currently does not take into consideration the fire-retardant materials charring rate under fire exposure.Design/methodology/approachHowever, currently these fire retardants are proving to be reliable and depending on their application can achieve better reaction-to-fire classifications. During the research, the authors used five different fire-retardant materials on three different types of wood and tested their behaviours in a laboratory. When selecting them, it was important to choose the species that are most commonly used in the building industry but which have significantly different densities. Our choice fell upon spruce (360 kg/m3), Scots pine (540 kg/m3) and oak (650 kg/m3). During the tests, we examined the weight reduction and the process of burning on the specimens treated with the fire retardant material. In addition, the authors also performed tests by derivatography on both untreated and treated specimen.FindingsThe question is whether the effects of the fire retardants should be taken into consideration when calculating the extent of the burn. The Eurocode (MSZ EN 1995-1-2) does not provide any opinions. On the market, there are manufacturers who are already discussing the possibilities of reducing the burn rate during the qualification of paints. In this paper, based on the results we received, we discuss the beneficial effects of the fire retardants which can be taken into account while measuring cross-sections.Originality/valueBy using fire retardants, a high proportion of cross-sectional area gain is only possible in case of small cross-sections; therefore, it is advisable to use them here as well. This can be effective for example in many smaller cross-sections, when there is a little space and therefore requires a small cross-section. Thus, if a larger cross-section without protection is not possible, it can be replaced by a smaller cross section, treated with a fire retardant.

scholarly journals Closed-form solutions for vibrations of a magneto-electro-elastic beam with variable cross section by means of Green’s functions

2018 ◽  
Vol 30 (1) ◽  
pp. 82-99 ◽  
Author(s):  
Xuan Ling Zhang ◽  
Xiao Chao Chen ◽  
Echuan Yang ◽  
Hai Feng Li ◽  
Jian Bo Liu ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Cross Section ◽  
Electric Potential ◽  
Green's Functions ◽  
Green’S Functions ◽  
Elastic Beam ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Cross Sectional ◽  
Closed Form Solutions

In this article, closed-form solutions are obtained for vibrations of a magneto-electro-elastic beam with variable cross section. Based on Timoshenko beam assumptions, governing equation for the non-uniform beam with exponentially varying width is obtained. Laplace transform approach applied to the governing equation results in the corresponding Green’s functions for the beams with various boundary conditions. The equations, which are solved to obtain Green’s functions, are degenerated for the analyses of the characters of free vibration. For free vibrations of the beams under different mechanical boundary conditions, the effects of the non-uniformly cross-sectional parameters and magneto-electric boundary conditions on the dynamic characters are studied. In addition, the magneto-electric potential modal variables’ distributions through the thickness are presented. In the discussions of forced vibration, two points in the beam are selected to investigate frequency responses in terms of displacement and magneto-electric potential. Moreover, the influences of excitation frequency and cross-sectional parameter on through-the-thickness distributions of electric potentials are investigated.

Always available – the role of perceived advantages and legitimacy

2018 ◽  
Vol 33 (7/8) ◽  
pp. 497-510 ◽  
Author(s):  
Jan Dettmers ◽  
Jana Biemelt
Keyword(s):  
Individual Differences ◽  
Boundary Conditions ◽  
Well Being ◽  
Moderating Effect ◽  
Online Questionnaire ◽  
Cross Sectional ◽  
Content Type ◽  
Reward Imbalance ◽  
Risk Reducing

Purpose Studies have shown that availability for work during non-work hours can impair well-being. However, there are significant inter-individual differences regarding these effects. Referring to the “effort–reward–imbalance” model and the “stress-as-offense-to-self” model, the purpose of this paper is to investigate the role that perceived advantages as well as the illegitimacy of extended availability plays in explaining the inter-individual differences. Design/methodology/approach A total of 310 participants completed an online questionnaire that measured extended availability, illegitimacy of extended availability, advantages of availability and two strain indicators. The authors conducted regression analyses to analyze the effects of extended availability on strain and the moderating role of perceived illegitimacy and advantages of extended availability. Findings Extended availability and – beyond this effect – perceived illegitimacy of extended availability were positively correlated with strain, whereas perceived advantages showed the opposite effect. Furthermore, perceived advantages had a moderating effect in that high advantages buffered the detrimental effects of extended availability. Research limitations/implications The results are based on cross-sectional data. However, the findings confirm previous research indicating that the detrimental effects of extended availability are dependent on specific boundary conditions. In this study, the authors provided evidence for the moderating effect of perceived advantages regarding extended availability. Practical implications The results provided indications to designing availability in a risk-reducing way by accounting for boundary conditions that may increase or decrease the detrimental effects. Originality/value By focusing on perceived illegitimacy and flexibility advantages as boundary conditions for the effects of extended availability, the study introduces two established concepts into the research on increasingly flexible work–home boundaries.

Sign in / Sign up

Export Citation Format

Share Document