Dynamic Behavior of FGM Doubly Curved Panel due to Mechanical Loading

2019 ◽  
Vol 950 ◽  
pp. 200-204
Author(s):  
Guang Ping Zou ◽  
Nadiia Dergachova
Keyword(s):  
Mechanical Loading ◽  
Volume Fraction ◽  
Equivalent Stress ◽  
Functionally Graded ◽  
Excitation Mode ◽  
Simply Supported ◽  
Curved Panel ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Doubly Curved

This study presents the dynamic response analyze of a simply supported and isotropic functionally graded (FG) double curved panel under mechanical loading. The aim of the research was to investigate mechanical behavior in a FGM curved panel due to different excitation mode of dynamic loading. The novelty of this research is an investigation of von Mises equivalent stress distribution in double curved panel due to different excitation mode. Computed results are found to agree well with the results reported in the literature. Moreover, influence of volume fraction of the material is studied.

scholarly journals An Intrinsic Material Tailoring Approach for Functionally Graded Axisymmetric Hollow Bodies Under Plane Elasticity

2021 ◽  
Author(s):  
Hassan Mohamed Abdelalim Abdalla ◽  
Daniele Casagrande
Keyword(s):  
Optimization Problem ◽  
Volume Fraction ◽  
Minimum Principle ◽  
Equivalent Stress ◽  
Micromechanical Model ◽  
Plane Elasticity ◽  
Functionally Graded ◽  
Pontryagin Minimum Principle ◽  
Volume Fractions ◽  
Material Tailoring

AbstractOne of the main requirements in the design of structures made of functionally graded materials is their best response when used in an actual environment. This optimum behaviour may be achieved by searching for the optimal variation of the mechanical and physical properties along which the material compositionally grades. In the works available in the literature, the solution of such an optimization problem usually is obtained by searching for the values of the so called heterogeneity factors (characterizing the expression of the property variations) such that an objective function is minimized. Results, however, do not necessarily guarantee realistic structures and may give rise to unfeasible volume fractions if mapped into a micromechanical model. This paper is motivated by the confidence that a more intrinsic optimization problem should a priori consist in the search for the constituents’ volume fractions rather than tuning parameters for prefixed classes of property variations. Obtaining a solution for such a class of problem requires tools borrowed from dynamic optimization theory. More precisely, herein the so-called Pontryagin Minimum Principle is used, which leads to unexpected results in terms of the derivative of constituents’ volume fractions, regardless of the involved micromechanical model. In particular, along this line of investigation, the optimization problem for axisymmetric bodies subject to internal pressure and for which plane elasticity holds is formulated and analytically solved. The material is assumed to be functionally graded in the radial direction and the goal is to find the gradation that minimizes the maximum equivalent stress. A numerical example on internally pressurized functionally graded cylinders is also performed. The corresponding solution is found to perform better than volume fraction profiles commonly employed in the literature.

An Analysis of Filament Overwound Toroidal Pressure Vessels and Optimum Design of Such Structures

2002 ◽  
Vol 124 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Shuguang Li ◽  
John Cook
Keyword(s):  
Optimum Design ◽  
Equivalent Stress ◽  
Mechanical Damage ◽  
Stress Rupture ◽  
Optimization Procedure ◽  
Pressure Vessels ◽  
Thickness Variation ◽  
Von Mises Equivalent Stress ◽  
Metal Liner ◽  
Von Mises

This paper is concerned with the membrane shell analysis of filament overwound toroidal pressure vessels and optimum design of such pressure vessels using the results of the analysis by means of mathematical nonlinear programming. The nature of the coupling between overwind and linear has been considered based on two extreme idealizations. In the first, the overwind is rigidly coupled with the liner, so that the two deform together in the meridional direction as the vessel dilates. In the second, the overwind is free to slide relative to the linear, but the overall elongations of the two around a meridian are identical. Optimized designs with the two idealizations show only minor differences, and it is concluded that either approximation is satisfactory for the purposes of vessel design. Aspects taken into account are the intrinsic overwind thickness variation arising from the winding process and the effects of fiber pre-tension. Pre-tension can be used not only to defer the onset of yielding, but also to achieve a favorable in-plane stress ratio which minimizes the von Mises equivalent stress in the metal liner. Aramid fibers are the most appropriate fibers to be used for the overwind in this type of application. The quantity of fiber required is determined by both its short-term strength and its long-term stress rupture characteristics. An optimization procedure for the design of such vessels, taking all these factors into account, has been established. The stress distributions in the vessels designed in this way have been examined and discussed through the examples. A design which gives due consideration of possible mechanical damage to the surface of the overwind has also been addressed.

Biomechanical Behavior of All-Ceramic Crowns with Variable Thicknesses of Zirconia Frameworks

2016 ◽  
Vol 835 ◽  
pp. 97-102
Author(s):  
Liliana Porojan ◽  
Florin Topală ◽  
Sorin Porojan
Keyword(s):  
Mechanical Behavior ◽  
Equivalent Stress ◽  
The Finite Element Method ◽  
Static Loads ◽  
Biomechanical Behavior ◽  
All Ceramic ◽  
Ceramic Crowns ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Posterior Restorations

Zirconia is an extremely successful material for prosthetic restorations, offering attractive mechanical and optical properties. It offers several advantages for posterior restorations because it can withstand physiological posterior forces. The aim of the study was to achieve the influence of zirconia framework thickness on the mechanical behavior of all-ceramic crowns using numerical simulation. For the study a premolar was chosen in order to simulate the mechanical behavior in the components of all-ceramic crowns and teeth structures regarding to the zirconia framework thickness. Maximal Von Mises equivalent stress values were recorded in teeth and restorations. Due to the registered maximal stress values it can be concluded that it is indicated to achieve frameworks of at least 0.5 mm thickness in the premolar area. Regarding stress distribution concentration were observed in the veneer around the contact areas with the antagonists, in the framework under the functional cusp and in the oral part overall and in dentin around and under the marginal line, also oral. The biomechanical behavior of all ceramic crowns under static loads can be investigated by the finite element method.

Vibrations of rotating cylindrical shells with functionally graded material using wave propagation approach

2018 ◽  
Vol 232 (23) ◽  
pp. 4342-4356 ◽  
Author(s):  
Muzammal Hussain ◽  
M Nawaz Naeem ◽  
Aamir Shahzad ◽  
Mao-Gang He ◽  
Siddra Habib
Keyword(s):  
Wave Propagation ◽  
Natural Frequencies ◽  
Volume Fraction ◽  
Cylindrical Shells ◽  
Functionally Graded ◽  
Wave Number ◽  
Type I ◽  
Rotating Speed ◽  
Simply Supported ◽  
Fundamental Frequencies

Fundamental natural frequencies of rotating functionally graded cylindrical shells have been calculated through the improved wave propagation approach using three different volume fraction laws. The governing shell equations are obtained from Love’s shell approximations using improved rotating terms and the new equations are obtained in standard eigenvalue problem with wave propagation approach and volume fraction laws. The effects of circumferential wave number, rotating speed, length-to-radius, and thickness-to-radius ratios have been computed with various combinations of axial wave numbers and volume fraction law exponent on the fundamental natural frequencies of nonrotating and rotating functionally graded cylindrical shells using wave propagation approach and volume fraction laws with simply supported edge. In this work, variation of material properties of functionally graded materials is controlled by three volume fraction laws. This process creates a variation in the results of shell frequency. MATLAB programming has been used to determine shell frequencies for traveling mode (backward and forward) rotating motions. New estimations show that the rotating forward and backward simply supported fundamental natural frequencies increases with an increase in circumferential wave number, for Type I and Type II of functionally graded cylindrical shells. The presented results of backward and forward simply supported fundamental natural frequencies corresponding to Law I are higher than Laws II and III for Type I and reverse effects are found for Type II, depending on rotating speed. Our investigations show that the decreasing and increasing behaviors are noted for rotating simply supported fundamental natural frequencies with increasing length-to-radius and thickness-to-radius ratios, respectively. It is found that the fundamental frequencies of the forward waves decrease with the increase in the rotating speed, and the fundamental frequencies of the backward waves increase with the increase in the rotating speed. This investigation has been made with three different volume fraction laws of polynomial (Law I), exponential (Law II), and trigonometric (Law III). The presented numerical results of nonrotating isotropic and rotating functionally graded simply supported are in fair agreement with parts of other earlier numerical results.

scholarly journals Investigation of porosity effect on flexural analysis of doubly curved FGM conoids

2019 ◽  
Vol 26 (1) ◽  
pp. 435-448
Author(s):  
Md Irfan Ansari ◽  
Ajay Kumar ◽  
Danuta Barnat-Hunek ◽  
Zbigniew Suchorab ◽  
Bartłomiej Kwiatkowski
Keyword(s):  
Mathematical Model ◽  
Shear Strain ◽  
Transverse Shear ◽  
Volume Fraction ◽  
Current Model ◽  
Lower Surface ◽  
Functionally Graded ◽  
Transverse Shear Strain ◽  
Flexural Analysis ◽  
Doubly Curved

AbstractThe flexural analysis of doubly curved functionally graded porous conoids was performed in the present paper. The porosities inside functionally graded materials (FGMs) can occur during the fabrication and lead to the occurrence of micro-voids in the materials. The mathematical model includes expansion of Taylor’s series up to the third degree in thickness coordinate and normal curvatures in in-plane displacement fields. Since there is a parabolic variation in transverse shear strain deformation across the thickness coordinate, the shear correction factor is not necessary. The condition of zero-transverse shear strain at upper and lower surface of conoidal shell is implemented in the present model. The improvement in the 2D mathematical model enables to solve problems of moderately thick FGM porous conoids. The distinguishing feature of the present shell from the other shells is that maximum transverse deflection does not occur at its centre. The improved mathematical model was implemented in finite element code written in FORTRAN. The obtained numerical results were compared with the results available in the literature. Once validated, the current model was employed to study the effect of porosity, boundary condition, volume fraction index, loading pattern and others geometric parameters.

Mechanical Properties and Experimental Study of a Composite Polishing Plate during Super-High Polishing

2010 ◽  
Vol 135 ◽  
pp. 337-342
Author(s):  
Li Zhou ◽  
Shu Tao Huang ◽  
Li Fu Xu
Keyword(s):  
Chemical Reaction ◽  
High Speed ◽  
Equivalent Stress ◽  
Stress Distributions ◽  
Centrifugal Forces ◽  
X Ray ◽  
High Speed Rotation ◽  
Speed Rotation ◽  
Von Mises Equivalent Stress ◽  
Von Mises

A new composite polishing plate for polishing of CVD diamond films has been designed. The displacement and stress distributions of the high speed rotation polishing plate have been investigated due to centrifugal forces, and the polishing mechanism of super-high polishing has been analyzed by using X-ray photo-electron spectroscopy. The results showed that the displacements both in axial and radial increase with the increasing of the rotational speed. When the rotation speed reached to 1200 rad/s, the von Mises equivalent stress is about 242 MPa, which is safe for the composite polishing plate. Additional, the polishing mechanism is mainly the chemical reaction between carbon and titanium during the super-high speed polishing. At elevated temperature, the chemical reaction between oxygen and titanium, oxygen and carbon can also occur.

The effects of shape memory alloys’ tension–compression asymmetryon NiTi endodontic files’ fatigue life

2018 ◽  
Vol 232 (5) ◽  
pp. 437-445 ◽  
Author(s):  
MR Karamooz-Ravari ◽  
R Dehghani
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Element Model ◽  
Niti Shape Memory Alloy ◽  
Element Analysis ◽  
Tension And Compression ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Nowadays, NiTi rotary endodontic files are of great importance due to their flexibility which enables the device to cover all the portions of curved canal of tooth. Although this class of files are flexible, intracanal separation might happen during canal preparation due to bending or torsional loadings of the file. Since fabrication and characterization of such devices is challenging, time-consuming, and expensive, it is preferable to predict this failure before fabrication using numerical models. It is demonstrated that NiTi shape memory alloy shows asymmetric material response in tension and compression which can significantly affect the lifetime of the files fabricated from. In this article, the effects of this material asymmetry on the bending response of rotary files are assessed using finite element analysis. To do so, a constitutive model which takes material asymmetry into account is used in combination with the finite element model of a RaCe file. The results show that the material asymmetry can significantly affect the maximum von Mises equivalent stress as well as the force–displacement response of the tip of this file.

Impact of Grooves in Hydraulically Expanded Tube-to-Tubesheet Joints

2020 ◽  
Author(s):  
Dinu Thomas Thekkuden ◽  
Abdel-Hamid I. Mourad ◽  
Abdel-Hakim Bouzid
Keyword(s):  
Contact Pressure ◽  
Equivalent Stress ◽  
Pull Out ◽  
Expansion Pressure ◽  
Loading And Unloading ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Maximum Contact ◽  
Pull Out Strength

Abstract The stress corrosion cracking of tube-to-tubesheet joints is one of the major faults causing heat exchanger failure. After the expansion process, the stresses are developed in a plastically deformed tube around the tube-to-tubesheet joint. These residual stressed joints, exposed to tube and shell side fluids, are the main crack initiation sites. Adequate contact pressure at the tube-to-tubesheet interface is required to produce a quality joint. Insufficient tube-to-tubesheet contact pressure leads to insufficient joint strength. Therefore, a study on the residual stress and contact pressure that have a great significance on the quality of the tube-to-tubesheet joint is highly demanded. In this research, a 2D axisymmetric numerical analysis is performed to study the effect of the presence of grooves in the tubesheet and the expansion pressure length on the distribution of contact pressure and stress during loading and unloading of 400 MPa expansion pressure. The results show that the maximum contact pressure is independent of the expansion pressure length. However, the presence of grooves significantly increased the maximum contact pressure. It is proven that the presence of grooves in the tubesheet is distinguishable from the maximum contact pressure and residual von mises equivalent stress. The tube pull-out strength increases with the expansion pressure and the number of grooves. In conclusion, the presence of the grooves affects the tube-to-tubesheet joints.

Research on Residual Strength of Corroded Tubing of Gas Well With Sustained Casing Pressure

2015 ◽  
Author(s):  
Li Sun ◽  
Jianchun Fan ◽  
Xing Meng ◽  
Ximing Zhang ◽  
Yuting Sun ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Residual Strength ◽  
Equivalent Stress ◽  
External Pressure ◽  
Defect Depth ◽  
Gas Well ◽  
Sustained Casing Pressure ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Casing Pressure

Corrosion and sustained casing pressure have serious threats to the integrity of tubing of gas well. Researching the residual strength of corroded tubing has great significance to ensure the safety of gas well. The finite element method was used to study the relationships between residual strength and corrosion defects size, internal pressure, external pressure, axial load. The results show that, for tubing with uniform corrosion, the defect depth, internal pressure and external pressure have greater impacts on the von Mises equivalent stress of tubing, and the defect width and defect length have little effects on it. For tubing with pitting corrosion, the defect depth, internal pressure and external pressure have greater impacts on the von Mises equivalent stress of tubing, while the defect radius has little effect on it. These simulation data were fitted into the functions of residual strength of corroded tubing according to different corrosion morphology types. Both of the verifications of the fitting results show that most of the error between the original calculation data and the fitting calculation data is less than 4%. The fitting formulas can be used conveniently to evaluate the safety of the tubing of gas well with sustained casing pressure.

Non-linear thermo-mechanical cylindrical bending of functionally graded plates

2008 ◽  
Vol 222 (3) ◽  
pp. 305-318 ◽  
Author(s):  
F Fallah ◽  
A Nosier
Keyword(s):  
Boundary Conditions ◽  
Volume Fraction ◽  
Functionally Graded ◽  
Power Law Distribution ◽  
Cylindrical Bending ◽  
Closed Form Solutions ◽  
Simply Supported ◽  
Fg Plates ◽  
Non Linear ◽  
The One

Based on the first-order non-linear von Karman theory, cylindrical bending of functionally graded (FG) plates subjected to mechanical, thermal, and combined thermo-mechanical loadings are investigated. Analytical solutions are obtained for an FG plate with various clamped and simply-supported boundary conditions. The closed form solutions obtained are very simple to be used in design purposes. The material properties are assumed to vary continuously through the thickness of the plate according to a power-law distribution of the volume fraction of the constituents. The effects of non-linearity, material property, and boundary conditions on various response quantities are studied and discussed. It is found that linear analysis is inadequate for analysis of simply-supported FG plates even in the small deflection range especially when thermal load is present. Also it is shown that bending—extension coupling can not be seen in response quantities of clamped FG plates. Also an exact solution is developed for the one-dimensional heat conduction equation with variable heat conductivity coefficient.

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