Elastic-Plastic Analysis for Functionally Graded Thick-Walled Tube Subjected to Internal Pressure

2016 ◽  
Vol 8 (2) ◽  
pp. 331-352 ◽  
Author(s):  
Libiao Xin ◽  
Guansuo Dui ◽  
Shengyou Yang ◽  
Ying Liu
Keyword(s):  
Internal Pressure ◽  
Yield Criterion ◽  
Functionally Graded ◽  
Power Functions ◽  
Unknown Parameters ◽  
Volume Fractions ◽  
Elastic Plastic ◽  
Graded Material ◽  
Two Phases ◽  
Elastic Plastic Materials

AbstractThe elastic-plastic response of the functionally graded thick-walled tube subjected to internal pressure is investigated by using the relation of the volume average stresses of constituents and the macroscopic stress of composite material in micromechanics. The tube consists of two idealized isotropic elastic-plastic materials whose volume fractions are power functions of the radius. As the internal pressure increases, the deformations of one phase and two phases from elastic to plastic are analyzed. In order to simplify the calculations we assume both materials with the same Poisson's ratio. By using the assumption of a uniform strain field within the representative volume element and the Tresca yield criterion, the theoretical solutions are obtained for the case of two elastic phases and the case of two plastic phases, and the function of the radial displacement is presented for the case with both elastic and plastic phases. The yield criterion of functionally graded material is given in terms of the yield stresses and volume fractions of constituents rather than Young's modulus and yield stress with different unknown parameters of the whole material in the existing papers. Finally we also discuss the position where the plastic deformation first occurs and the conditions for which material first yields in the tube.

scholarly journals Lamb Waves in a Functionally Graded Composite Plate with Nonintegral Power Function Volume Fractions

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaoshan Cao ◽  
Zhen Qu ◽  
Junping Shi ◽  
Yan Ru
Keyword(s):  
Differential Equations ◽  
Lamb Waves ◽  
Variable Coefficients ◽  
Functionally Graded ◽  
Power Functions ◽  
Volume Fractions ◽  
Functionally Graded Composite ◽  
Propagation Behavior ◽  
Graded Material ◽  
Thermal Stress Relaxation

An analytical modelling is carried out to determine the Lamb wave’s propagation behavior in a thermal stress relaxation type functionally graded material (FGM) plate, which is a composite of two kinds of materials. The mechanical parameters depend on the volume fractions, which are nonintegral power functions, and the gradient coefficient is the power value. Based on the theory of elastodynamics, differential equations with variable coefficients are established. We employ variable substitution for theoretical derivations to solve the ordinary differential equations with variable coefficients using the Taylor series. The numerical results reveal that the dispersion properties in some regions are changed by the graded property, the phase velocity varies in a nonlinear manner with the gradient coefficient, nondispersion frequency exists in the first mode, and the set of cutoff frequencies is a union of two series of approximate arithmetic progressions. These results provide theoretical guidance not only for the experimental measurement of material properties but also for their nondestructive testing.

Free Vibration and Elastic Critical Load of Functionally Graded Material Thin Cylindrical Shells Under Internal Pressure

2018 ◽  
Vol 18 (11) ◽  
pp. 1850138 ◽  
Author(s):  
Yueyang Han ◽  
Xiang Zhu ◽  
Tianyun Li ◽  
Yunyan Yu ◽  
Xiaofang Hu
Keyword(s):  
Cylindrical Shell ◽  
Free Vibration ◽  
Internal Pressure ◽  
Critical Load ◽  
Natural Frequency ◽  
Functionally Graded Material ◽  
Present Method ◽  
Cylindrical Shells ◽  
Functionally Graded ◽  
Graded Material

An analytical approach for predicting the free vibration and elastic critical load of functionally graded material (FGM) thin cylindrical shells filled with internal pressured fluid is presented in this study. The vibration of the FGM cylindrical shell is described by the Flügge shell theory, where the internal static pressure is considered as the prestress term in the shell equations. The motion of the internal fluid is described by the acoustic wave equation. The natural frequencies of the FGM cylindrical shell under different internal pressures are obtained with the wave propagation method. The relationship between the internal pressure and the natural frequency of the cylindrical shell is analyzed. Then the linear extrapolation method is employed to obtain the elastic critical load of the FGM cylindrical shell from the condition that the increasing pressure has resulted in zero natural frequency. The accuracy of the present method is verified by comparison with the published results. The effects of gradient index, boundary conditions and structural parameters on the elastic critical load of the FGM cylindrical shell are discussed. Compared with the experimental and numerical analyses based on the external pressure, the present method is simple and easy to carry out.

scholarly journals Numerical solution of thermal elastic-plastic functionally graded thin rotating disk with exponentially variable thickness and variable density

2019 ◽  
Vol 23 (1) ◽  
pp. 125-136 ◽  
Author(s):  
Sanjeev Sharma ◽  
Sanehlata Yadav
Keyword(s):  
Strain Hardening ◽  
Functionally Graded Material ◽  
Circumferential Stress ◽  
Rotating Disk ◽  
Functionally Graded ◽  
Linear Strain ◽  
Annular Disk ◽  
Elastic Plastic ◽  
Non Linear ◽  
Graded Material

Thermal elastic-plastic stresses and strains have been obtained for rotating annular disk by using finite difference method with Von-Mises? yield criterion and non-linear strain hardening measure. The compressibility of the disk is assumed to be varying in the radial direction. From the numerical results, we can conclude that thermal rotating disk made of functionally graded material whose thickness decreases exponentially and density increases exponentially with non-linear strain hardening measure (m = 0.2) is on the safe side of the design as compared to disk made of homogenous material. This is because of the reason that circumferential stress is less for functionally graded disk as compared to homogenous disk. Also, plastic strains are high for functionally graded disk as compared to homogenous disk. It means that disk made of functionally graded material reduces the possibility of fracture at the bore as compared to the disk made of homogeneous material which leads to the idea of stress saving.

Axisymmetric Elastoplasticity of a Temperature-Sensitive Functionally Graded Cylindrical Vessel

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Mojtaba Sadeghian ◽  
Hamid Ekhteraei Toussi
Keyword(s):  
Plastic Material ◽  
Yield Criterion ◽  
Small Deformation ◽  
Functionally Graded ◽  
Cylindrical Vessel ◽  
Linear Functions ◽  
Temperature Sensitive ◽  
Power Functions ◽  
Closed Form Solutions ◽  
Perfectly Plastic

Based on the small deformation theory and Tresca's yield criterion an axisymmetric, plane strain, elastoplastic, thermal stress analysis for a cylindrical vessel made of functionally graded elastic, perfectly plastic material is offered. Elastic modulus and yield strength coefficients are assumed to be power functions of radius and linear functions of temperature. A cylindrical vessel is taken to be composed of two or more nested fully elastic and perfectly plastic cylinders. By comparing the values of the deformation or stress components in the interfaces of the neighboring cylinders, a system of equations is formed. The interfacial boundary values of the fully elastic or perfectly plastic regions are obtained by simultaneous solution of the resulting interfacial consistency conditions. Having prepared the closed form solutions for the stress fields in purely elastic and purely plastic regions, the distribution of stress throughout the vessel can be obtained. Using this model, in some sample problems, the influences of temperature and pressure on the stress, strain, and plastic zone patterns are studied. The location of plastic zones is obtained for a class of material property compositions.

Analytical Solution for Strain Gradient Plasticity of Rotating Functionally Graded Thick Cylinders

2020 ◽  
Vol 12 (07) ◽  
pp. 2050082
Author(s):  
Saeid Varmazyari ◽  
Hassan Shokrollahi
Keyword(s):  
Analytical Solution ◽  
Strain Gradient ◽  
Yield Criterion ◽  
External Pressure ◽  
Functionally Graded ◽  
Strain Gradient Theory ◽  
Gradient Theory ◽  
Gradient Plasticity ◽  
Elastic Plastic ◽  
Von Mises

The elastic-plastic deformation of rotating functionally graded (FG) cylinders is investigated based on strain gradient theory. The governing equations are obtained based on the modified von Mises yield criterion, linear work hardening and plane strain assumptions. An analytical solution for the obtained equations is presented by which the deformation, strain and stress components for any point of the cylinder can be obtained. After verification of the formulation by comparing the obtained results with the reported results in the literature, some studies are presented to investigate the effects of cylinder size on the stress distribution and elastic-plastic interface radius of the rotating FG cylinder under internal and external pressure. The effects of the strain gradient coefficient, angular velocity, and the heterogeneity constant of the material are investigated. The results show that increasing the heterogeneity constant of the material and decreasing the cylinder radius lead to increasing the strength of material and decreasing the elastic-plastic interface radius. Moreover, classical theory is compared with this study and the range of the sizes in which both the theories leading to the same results, are defined.

One-Dimensional Moving Heat Source in a Hollow FGM Cylinder

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
M. Jabbari ◽  
A. H. Mohazzab ◽  
A. Bahtui
Keyword(s):  
Heat Source ◽  
Hollow Cylinder ◽  
Thermal Stresses ◽  
Direct Method ◽  
Functionally Graded ◽  
Moving Heat Source ◽  
Power Functions ◽  
One Dimensional ◽  
Generalized Bessel Function ◽  
Graded Material

This paper presents the analytical solution of one-dimensional mechanical and thermal stresses for a hollow cylinder made of functionally graded material. The material properties vary continuously across the thickness, according to the power functions of radial direction. Temperature distribution is symmetric and transient. The thermal boundary conditions may include conduction, flux, and convection for inside or outside of a hollow cylinder. The thermoelasticity equation is transient, including the moving heat source. The heat conduction and Navier equations are solved analytically, using the generalized Bessel function. A direct method of solution of Navier equation is presented.

General Solution for Equation of Transient Heat Conduction in Functionally Graded Material Hollow Cylinder With Piezoelectric Internal and External Layers

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
M. Jabbari ◽  
M. A. Kiani
Keyword(s):  
Heat Conduction ◽  
Hollow Cylinder ◽  
Functionally Graded Material ◽  
Separation Of Variables ◽  
Transient Heat Conduction ◽  
Two Dimensions ◽  
Functionally Graded ◽  
Power Functions ◽  
Generalized Bessel Function ◽  
Graded Material

In this paper, the exact solution of the equation of transient heat conduction in two dimensions for a hollow cylinder made of functionally graded material (FGM) and piezoelectric layers is developed. Temperature distribution, as function of radial and circumferential directions and time, is analytically obtained for different layers, using the method of separation of variables and generalized Bessel function. The FGM properties are assumed to depend on the variable r, and they are expressed as power functions of r.

scholarly journals Calculation of Volume Fractions of In Situ TiB and Residual Stress Distributions in Functionally Graded Composite of Ti–TiB–TiB2

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4006
Author(s):  
Youfeng Zhang ◽  
Shasha He ◽  
Wanwan Yang ◽  
Jiangwei Ren ◽  
Haijuan Kong
Keyword(s):  
Residual Stress ◽  
Matrix Composite ◽  
Target Volume ◽  
Functionally Graded ◽  
Gradient Field ◽  
Stress Distributions ◽  
Volume Fractions ◽  
Functionally Graded Composite ◽  
The Matrix ◽  
Graded Material

Ti matrix composite with a polylaminate structure was successfully fabricated via spark plasma sintering (SPS) process. A temperature gradient field (TGF) was obtained during the sintering to form functionally graded material (FGM) in a vacuum under 40 MPa for 5 min. The actual volume fractions of TiB in the matrix were calculated based on the X-ray diffraction pattern. The target volume fractions of TiB were 0%, 20%, 40%, 60%, 80% and 100%. The calculated TiB volume fractions were slightly higher than the target volume fractions in layers 2–4 and lower than the target volume fractions in layers 5–6 and the deviations in layers 4 and 5 were less than 5% of the target volume. Based on the elastic axial symmetry model, the residual stress distributions in the Ti matrix composite with a polylaminate structure were simulated, indicating a relatively low thermal residual stress in the FGM.

Asymptotic Crack-Tip Fields for Mixed Stationary Crack under Plane Stress Conditions in Pressure Sensitive and Elastic-Plastic Materials

2010 ◽  
Vol 146-147 ◽  
pp. 611-614
Author(s):  
Chen Hua Lu ◽  
Su Fang Xing ◽  
Wen Jia Wang ◽  
Jian Bing Sang ◽  
Bo Liu
Keyword(s):  
Plane Stress ◽  
Yield Criterion ◽  
Crack Tip ◽  
Flow Rule ◽  
Basic Solution ◽  
Crack Tip Field ◽  
Plane Stress Condition ◽  
Elastic Plastic ◽  
Pressure Sensitive ◽  
Elastic Plastic Materials

Based on the parabolic yield criterion reflected by pressure sensitive and the SD effect, the material constitutive equation is given by orthogonal flow rule. In the plane stress condition, a basic solution in elastic-plastic crack tip field is given. The different structures of solutions with different plastic mixity are analyzed. Different parameters in crack-tip stress field and the singularity in the strain field are discussed. These results provide a theoretical reference for engineering applications.

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