scholarly journals Characterization of Functionally Graded Timoshenko Beams with Variable Rotational Speed

2019 ◽  
Vol 8 (4) ◽  
pp. 5926-5931
Keyword(s):  
Rotational Speed ◽  
Angular Speed ◽  
Functionally Graded ◽  
Timoshenko Beams ◽  
The Finite Element Method ◽  
Axial Loads ◽  
Fgm Beam ◽  
The Stability ◽  
Good Agreement

This paper investigates the free vibration characteristics and stability of a functionally graded Timoshenko beam spinning with variable angular speed. Material properties of the beam are assumed to be varied continuously along the thickness of the beam according to a power law and exponential law. The results show that increasing beam rotational speed increases fundamental mode frequency and the beam becomes more and more stable at higher speeds. This paper reports the dynamic behaviour of a rotating FGM beam subjected to axial periodic forces using the finite element method. The numerical results show good agreement with the reported beams models. Effects of static and time dependent components of axial loads on the stability of the FGM beam have been studied.

Experimental Characterization of a T-Shaped Programmable Multistable Mechanism

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Mohamed Zanaty ◽  
Simon Henein
Keyword(s):  
Numerical Simulations ◽  
Reaction Force ◽  
Experimental Measurements ◽  
Experimental Characterization ◽  
Stable States ◽  
Stability Behavior ◽  
The Stability ◽  
Force Characteristics ◽  
Good Agreement

Programmable multistable mechanisms (PMM) exhibit a modifiable stability behavior in which the number of stable states, stiffness, and reaction force characteristics are controlled via their programming inputs. In this paper, we present experimental characterization for the concept of stability programing introduced in our previous work (Zanaty et al., 2018, “Programmable Multistable Mechanisms: Synthesis and Modeling,” ASME J. Mech. Des., 140(4), p. 042301.) A prototype of the T-combined axially loaded double parallelogram mechanisms (DPM) with rectangular hinges is manufactured using electrodischarge machining (EDM). An analytical model based on Euler–Bernoulli equations of the T-mechanism is derived from which the stability behavior is extracted. Numerical simulations and experimental measurements are conducted on programming the mechanism as monostable, bistable, tristable, and quadrastable, and show good agreement with our analytical derivations within 10%.

Vibration characteristics and stable region of a parabolic FGM thin-walled beam with axial and spinning motion

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Baichuan Lin ◽  
Bo Chen ◽  
Yinghui Li ◽  
Jie Yang
Keyword(s):  
Natural Frequencies ◽  
Angular Speed ◽  
Vibration Characteristics ◽  
Functionally Graded ◽  
Stable Region ◽  
Graded Material ◽  
Axially Moving ◽  
Fgm Beam ◽  
Spinning Speed ◽  
Axial Speed

Abstract This paper focuses on the vibration characteristics of the parabolic functionally graded material (FGM) beam considering the axially moving and spinning motion. Based on the Hamilton’s principle, the governing equation of the beam is derived. Then, the Galerkin’s method is employed to solve the equation. The combined influence of axial speed, spinning speed, and geometric parameters on natural frequencies of the beam are investigated. What’s more, the axially moving and spinning motion can lead to a critical axial speed and critical spinning angular speed, respectively. These two critical speeds and stable region affected by different parameters are also discussed.

scholarly journals Mechanical Property Variation of a Rotating Cantilever FGSW Beam under Parametric Excitation

2019 ◽  
Vol 8 (11) ◽  
pp. 495-499
Keyword(s):  
Shear Modulus ◽  
Power Law ◽  
Parametric Excitation ◽  
Excitation Power ◽  
Functionally Graded ◽  
Timoshenko Beams ◽  
Power Law Distribution ◽  
Property Variation ◽  
Graded Material ◽  
The Stability

We report here the dynamic stability of functionally graded sandwich (FGSW) rotating cantilever Timoshenko beams under parametric excitation. Power law with various indices as well as exponential law were used to find out the properties along the thickness of the FGSW beam. The stability boundaries were established using Floquet’s theory. The equation of motion was governed by Hamilton’s principle and solved by Finite element method. The power index was optimized for uniform variation of shear modulus along the thickness of FGSW beam.The shear modulus variation along the thickness of the FGSW beam was compared both by power law and exponential law.It has been confirmed that the Exponential distribution of constituent phases renders better stability compared to power law distribution of the phases in the functionally graded material(FGM).

scholarly journals Geometrically Nonlinear Static Analysis of Edge Cracked Timoshenko Beams Composed of Functionally Graded Material

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Şeref Doğuşcan Akbaş
Keyword(s):  
Finite Element ◽  
Static Analysis ◽  
Functionally Graded Material ◽  
Functionally Graded ◽  
Nonlinear Static Analysis ◽  
Geometrically Nonlinear ◽  
Timoshenko Beams ◽  
Graded Material ◽  
Nonlinear Static ◽  
Fgm Beam

Geometrically nonlinear static analysis of edge cracked cantilever Timoshenko beams composed of functionally graded material (FGM) subjected to a nonfollower transversal point load at the free end of the beam is studied with large displacements and large rotations. Material properties of the beam change in the height direction according to exponential distributions. The cracked beam is modeled as an assembly of two subbeams connected through a massless elastic rotational spring. In the study, the finite element of the beam is constructed by using the total Lagrangian Timoshenko beam element approximation. The nonlinear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. The convergence study is performed for various numbers of finite elements. In the study, the effects of the location of crack, the depth of the crack, and various material distributions on the nonlinear static response of the FGM beam are investigated in detail. Also, the difference between the geometrically linear and nonlinear analysis of edge cracked FGM beam is investigated in detail.

On Post-Buckling Behavior of Edge Cracked Functionally Graded Beams Under Axial Loads

2015 ◽  
Vol 15 (04) ◽  
pp. 1450065 ◽  
Author(s):  
Şeref Doğuşcan Akbaş
Keyword(s):  
Nonlinear Problems ◽  
Functionally Graded ◽  
Element Approximation ◽  
Axial Loads ◽  
Buckling Behavior ◽  
Highly Nonlinear ◽  
Compressive Loads ◽  
Graded Material ◽  
Post Buckling ◽  
Fgm Beam

This paper presents the post-buckling analysis of an edge cracked cantilever beam composed of functionally graded material (FGM) subjected to axial compressive loads by using the total Lagrangian Timoshenko beam element approximation. Material properties of the beam change in the height direction according to the exponential distribution. The cracked beam is modeled as an assembly of two sub-beams connected through a massless elastic rotational spring. For beams subjected to compression loads, the load rise causes compressible forces and therefore buckling and post-buckling phenomena occurs. It is known that post-buckling problems are geometrically nonlinear problems. The highly nonlinear problem considered herein is solved incrementally by using the finite element method in conjunction with the Newton–Raphson method, by which the full geometric nonlinearity is considered. There is no restriction on the magnitudes of deflections and rotations in contradistinction to the von Karman strain displacement relations of the beam. In the study, the effects of the location and depth of the crack, and different material distributions on the post-buckling behavior of the FGM beam are investigated in detail.

scholarly journals Análisis de los procesos de regresión y restitución del monumento natural Puente del Inca, Andes Centrales, Provincia de Mendoza, Argentina

2020 ◽  
Vol 47 (2) ◽  
pp. 446
Author(s):  
Esteban Lannutti ◽  
Maria Gabriela Lenzano ◽  
Jorge Baron ◽  
Marcelo Durand ◽  
Luis Lenzano
Keyword(s):  
Anthropogenic Factors ◽  
Thermal Waters ◽  
Heterogeneous Structure ◽  
The Finite Element Method ◽  
Resistant Material ◽  
Structural Regression ◽  
Natural Monument ◽  
The Stability ◽  
Natural And Anthropogenic Factors

The Puente del Inca, next to the homonymous village, is a natural bridge located on the Cuevas River, at about 2,700 m above sea level in the Central Andes of the province of Mendoza, Argentina. Declared Provincial Natural Monument in 2005, since the beginning of the 20th century it has registered a continuous weakening, mainly related to erosive processes that cause detachments of part of the material that makes up its structure. The objective of this study is to determine the factors involved in the structural regression and restitution of the natural bridge. To achieve this, visual inspection, characterization of thermal springs, measurement of accretion-erosion rate of travertine deposits, testing of materials and the development of a structural numerical model by the Finite Element Method, were carried out. Results indicate that the deterioration is linked, mainly, with changes in the geobiological system that regulates the travertine deposition and to the heterogeneous structure of the bridge. Changes of the geobiological system are related to the activity of the thermal waters present in the area, whose discontinuity and/or fluctuations in the flow rate are influenced by both natural and anthropogenic factors. The heterogeneity of the structure conditions the stability of the monument due to the presence of a less resistant material in the lower part of the bridge arch. From the numerical simulation, safety factors between 1.5 and 3 were determined for the bridge, thus, we conclude the structure is stable against its own weight, as long as the bridge maintains the current conditions.

Vibration Analysis of Bidirectional Functionally Graded Timoshenko Beams Using Chebyshev Collocation Method

2020 ◽  
pp. 2150009 ◽  
Author(s):  
Wei-Ren Chen ◽  
Heng Chang
Keyword(s):  
Collocation Method ◽  
Vibration Analysis ◽  
Free Vibration Analysis ◽  
Functionally Graded ◽  
Timoshenko Beams ◽  
Algebraic Equations ◽  
Chebyshev Collocation Method ◽  
Chebyshev Collocation ◽  
Proposed Model ◽  
Good Agreement

This paper studies the vibration behaviors of bidirectional functionally graded (BDFG) Timoshenko beams based on the Chebyshev collocation method. The material properties of the beam are assumed to vary simultaneously in the beam length and thickness directions. The Chebyshev differentiation matrices are used to reduce the ordinary differential equations into a set of algebraic equations to form the eigenvalue problem for free vibration analysis. To validate the accuracy of the proposed model, some calculated results are compared with those obtained by other investigators. Good agreement has been achieved. Then the effects of slenderness ratios, material distribution types, gradient indexes, and restraint types on the natural frequency of BDFG beams are examined. Through the parametric study, the influences of the various geometric and material parameters on the vibration characteristics of BDFG beams are evaluated.

scholarly journals Experimental Investigation on Rheological Properties of Water Based Novel Ternary Hybrid Nanofluids

2021 ◽  
Author(s):  
Mohammed Zayan ◽  
Abdul Khaliq Rasheed ◽  
Akbar John ◽  
Mohammed Khalid ◽  
Ahmad Faris
Keyword(s):  
Hybrid Nanoparticles ◽  
Damping Factor ◽  
Rheological Characterization ◽  
Viscosity Models ◽  
Water Based ◽  
Plastic Fluid ◽  
Linear Viscoelastic ◽  
The Stability ◽  
Good Agreement

This study presents the rheological characterization of deionised water dispersed with two different ternary-hybrid nanoparticles namely, GO-TiO2-Ag and rGO-TiO2-Ag. The stability of 0.05 wt% nanofluid samples are serially diluted by 10 fold in 5 levels is determined using zeta potential measurements. The non-linear viscoelastic measurements at temperatures ranging from 25oC to 50oC reveal that the graphene based ternary hybrid nanoparticle nanofluids exhibit Newtonian behaviour at higher concentrations. However, it displays shear thinning or pseudo-plastic fluid characteristics at lower concentration, suggesting a potential influence of nanoparticle aggregation on the viscosity. The experimental results are found to be in good agreement with the existing water based viscosity models. In addition, the effect due to shear stress, angular sweep, frequency sweep and damping factor ratio is also plotted.

scholarly journals Experimental Investigation on Rheological Properties of Water Based Novel Ternary Hybrid Nanofluids

2021 ◽  
Author(s):  
Mohammed Zayan ◽  
Abdul Khaliq Rasheed ◽  
Akbar John ◽  
Mohammed Khalid ◽  
Ahmad Faris
Keyword(s):  
Hybrid Nanoparticles ◽  
Damping Factor ◽  
Rheological Characterization ◽  
Viscosity Models ◽  
Water Based ◽  
Plastic Fluid ◽  
Linear Viscoelastic ◽  
The Stability ◽  
Good Agreement

This study presents the rheological characterization of deionised water dispersed with two different ternary-hybrid nanoparticles namely, GO-TiO2-Ag and rGO-TiO2-Ag. The stability of 0.05 wt% nanofluid samples are serially diluted by 10 fold in 5 levels is determined using zeta potential measurements. The non-linear viscoelastic measurements at temperatures ranging from 25oC to 50oC reveal that the graphene based ternary hybrid nanoparticle nanofluids exhibit Newtonian behaviour at higher concentrations. However, it displays shear thinning or pseudo-plastic fluid characteristics at lower concentration, suggesting a potential influence of nanoparticle aggregation on the viscosity. The experimental results are found to be in good agreement with the existing water based viscosity models. In addition, the effect due to shear stress, angular sweep, frequency sweep and damping factor ratio is also plotted.

scholarly journals Effect of Hub Radius on Rotational Stability of Functionally Graded Timoshenko Beams

2019 ◽  
Vol 9 (1) ◽  
pp. 4246-4251
Keyword(s):  
Exponential Distribution ◽  
Power Law ◽  
Functionally Graded ◽  
Rotational Stability ◽  
Timoshenko Beams ◽  
Power Law Distribution ◽  
Exponential Law ◽  
Radius Parameter ◽  
Graded Material ◽  
The Stability

This work is concerned to examine the rotational stability of functionally graded cantilever Timoshenko beams. Power law with various indices as well as exponential law were used to find out the effect of hub radius parameter on the stability of both functionally graded ordinary (FGO) beam. Floquet’s theory was used to establish the stability boundaries. The governing equation of motion was followed by Hamilton’s principle and solved by Finite element method. Dependence of Bulk modulus on thickness of beam was studied using both power law and exponential distribution. The influence of hub radius parameter was found to be enhancing the stability of FGO beams. It has further been confirmed that the effect of hub radius with exponential distribution of constituent phases renders better stability compared to power law distribution of the phases in the functionally graded material(FGM).

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