scholarly journals Elasto-Plastic Stresses in a Functionally Graded Rotating Disk

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Babak Haghpanah Jahromi ◽  
Hamid Nayeb-Hashemi ◽  
Ashkan Vaziri
Keyword(s):  
Stress Distribution ◽  
Stress Field ◽  
Mechanical Response ◽  
Rotating Disk ◽  
Outer Edge ◽  
Outer Radius ◽  
Disk Center ◽  
Functionally Graded ◽  
Von Mises Stress ◽  
Metal Ceramic

A numerical method based on the extension of the variable material property method was developed to obtain the elasto-plastic stress field in a functionally graded (FG) rotating disk. The method was applied to estimate the stress field in a metal–ceramic functionally graded solid disk. To establish the validity of the proposed method, results were compared with finite element results. Unlike uniform rotating disks, where yielding starts from the disk center, plasticity in FG disks can originate at any point. The effect of different metal–ceramic grading patterns as well as the relative elastic moduli and densities of the ceramic and metallic constituents on the developed stresses were studied. Reinforcement of a metal disk with ceramic particles, in both elastic and plastic regimes, can significantly influence the mechanical response of the disk such as the stress distribution and the critical angular velocities corresponding to the onset of plasticity in the disk and plastic disk. Disks with increasing ceramic content from inner to outer radius showed a more uniform von Mises stress distribution for a fixed value of total ceramic content. In contrast, disks with decreasing ceramic content from inner to outer radius had the lowest outer edge displacement for a fixed value of total ceramic content.

Displacement and Stress Fields in a Functionally Graded Fiber-Reinforced Rotating Disk With Nonuniform Thickness and Variable Angular Velocity

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Y. Zheng ◽  
H. Bahaloo ◽  
D. Mousanezhad ◽  
A. Vaziri ◽  
H. Nayeb-Hashemi
Keyword(s):  
Radial Direction ◽  
Volume Fraction ◽  
Rotating Disk ◽  
Outer Radius ◽  
Functionally Graded ◽  
Circumferential Direction ◽  
Stress Fields ◽  
Fiber Reinforced ◽  
Inner Radius ◽  
Nonuniform Thickness

Displacement and stress fields in a functionally graded (FG) fiber-reinforced rotating disk of nonuniform thickness subjected to angular deceleration are obtained. The disk has a central hole, which is assumed to be mounted on a rotating shaft. Unidirectional fibers are considered to be circumferentially distributed within the disk with a variable volume fraction along the radius. The governing equations for displacement and stress fields are derived and solved using finite difference method. The results show that for disks with fiber rich at the outer radius, the displacement field is lower in radial direction but higher in circumferential direction compared to the disk with the fiber rich at the inner radius. The circumferential stress value at the outer radius is substantially higher for disk with fiber rich at the outer radius compared to the disk with the fiber rich at the inner radius. It is also observed a considerable amount of compressive stress developed in the radial direction in a region close to the outer radius. These compressive stresses may prevent any crack growth in the circumferential direction of such disks. For disks with fiber rich at the inner radius, the presence of fibers results in minimal changes in the displacement and stress fields when compared to a homogenous disk made from the matrix material. In addition, we concluded that disk deceleration has no effect on the radial and hoop stresses. However, deceleration will affect the shear stress. Tsai–Wu failure criterion is evaluated for decelerating disks. For disks with fiber rich at the inner radius, the failure is initiated between inner and outer radii. However, for disks with fiber rich at the outer radius, the failure location depends on the fiber distribution.

Stress Analysis of a Functionally Graded Micro/ Nanorotating Disk with Variable Thickness Based on the Strain Gradient Theory

2016 ◽  
Vol 08 (02) ◽  
pp. 1650020 ◽  
Author(s):  
M. Baghani ◽  
N. Heydarzadeh ◽  
M. M. Roozbahani
Keyword(s):  
Variable Thickness ◽  
Strain Gradient ◽  
Mechanical Response ◽  
Rotating Disk ◽  
Functionally Graded ◽  
Strain Gradient Theory ◽  
Small Scale ◽  
Gradient Theory ◽  
Graded Materials ◽  
Remarkable Effect

In this paper, mechanical response of a micro/nanorotating disk made of functionally graded materials (FGMs) with variable thickness is investigated. Through utilizing variational method and considering the strain gradient theory, the governing equations and the boundary conditions are derived. In order to verify the developed formulation, in special limiting cases, the results are compared with those available in the literature. These comparisons show an excellent correspondence. Employing numerical techniques, some numerical results are presented to investigate the effect of variations of properties and thickness on the response of the small scale rotating disk. It is found that the non-homogeneity constants have a remarkable effect on the stress distribution in the FG rotating disk. Furthermore, the amount of stress could be reduced in the rotating disk through fabricating it with variable thickness.

On Transverse Vibrations of Functionally Graded Rotating Hollow Disk

2010 ◽  
Author(s):  
Rui Liu ◽  
Hamid Nayeb-Hashemi ◽  
Masoud Olia ◽  
Ashkan Vaziri
Keyword(s):  
Elastic Modulus ◽  
Critical Speed ◽  
Volume Fraction ◽  
Rotating Disk ◽  
Outer Radius ◽  
Functionally Graded ◽  
Distribution Functions ◽  
Rotating Disks ◽  
Disk Radius ◽  
Power Law Function

We studied the stress field and vibration characteristics of functionally graded rotating disks by solving the governing equation of motion using the finite difference scheme. The material was assumed to have a constant Poisson’s ratio with the elastic modulus varying as a power law function of the disk radius. Such a material could be developed by using particle reinforced composites with various reinforcements or reinforcement volume fraction. The results show that the first critical speed of the rotating disk could be increased by using FGMs. The first critical speed is greater for disks having higher elastic modulus at the outer radius. However, the disk may be unstable for certain distribution functions.

Computational Analysis of Stress Field and Contact Pressure for Rubber Seal Based on Non-Linear Finite Element

2012 ◽  
Vol 268-270 ◽  
pp. 1080-1083 ◽  
Author(s):  
Jian Bing Sang ◽  
Li Fang Sun ◽  
Su Fang Xing ◽  
Dong Ling Zhang
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Stress Field ◽  
Contact Stress ◽  
Von Mises Stress ◽  
Rubber Seal ◽  
Linear Finite Element ◽  
Maximum Contact Stress ◽  
Von Mises ◽  
Maximum Contact

This paper aims to research on the sealing capability of rubber seal by utlizing non-linear finite element analysis. After discussion on various types of strain energy functions of rubber like materials, material parameters of Mooney-Rivilin model are determined by curve fitting based on the stress strain curve from the uniaxial tensile experiment. Axis symmetric and isotropic finite element model is developed to analyze the stress field and contact pressue of O-ring seal and lip seal at different medium pressure. Von-mises stress distribution rule and contact stress distribution curve on contact surface are achieved. The results show that maximum Von Mises stress increase with the increases of oil pressure. The maximum contact stress appears on the middle contact zone and the maximum contact stress and contact width increases obviously with the increases of oil pressure. In the meanwhile, the maximum contact stress is greater than midum pressure which can prevent the leakage of midum and achieve the function of sealing. The research results will be a useful technique for predicting the properties of rubber seal and providing reference for engineering design.

Limit Elastic Analysis of FG Ceramic Rotating Disk on the Basis of Effective Mechanical Properties

2020 ◽  
Vol 978 ◽  
pp. 470-476
Author(s):  
Royal Madan ◽  
Kashi Nath Saha ◽  
Shubhankar Bhowmick
Keyword(s):  
Mechanical Properties ◽  
Rotating Disk ◽  
Ceramic Materials ◽  
Functionally Graded ◽  
Von Mises Stress ◽  
High Yield ◽  
Graded Materials ◽  
Unknown Variable ◽  
Von Mises ◽  
Effective Mechanical Properties

Functionally graded materials are prevalent among industries for its low weight compared to alloys. Depending upon the applications ceramic-ceramic materials can be graded to obtain novel functional combination. In a disk, yielding mainly occurs at the root, hence to overcome the yielding problem, Al2O3 material was used at the root and graded with different ceramics; as ceramics possess high yield strength. In composites, many methods are available to calculate effective mechanical properties and modified rule of mixture (MROM) is one of these. In MROM only single parameter, stress to strain transfer ratio needs to be identified which in present case was calculated using inverse approach i.e. by comparing Halpin-Tsai model with MROM. Variational formulation method was employed taking radial displacement field as unknown variable. The effective Young’s modulus calculated was then verified with experimental data and good agreement was seen. Further effective yield stress distribution was quantified and plotted to compare with von-Mises stress. Limit elastic speed then obtained was used to rank different ceramic-ceramic graded combinations. Limit speed defines the performance of disk and thus it was chosen as a selection parameter.

scholarly journals Analytical Investigation of Viscoelastic Stagnation-Point Flows with Regard to Their Singularity

2021 ◽  
Vol 11 (15) ◽  
pp. 6931
Author(s):  
Jie Liu ◽  
Martin Oberlack ◽  
Yongqi Wang
Keyword(s):  
Stress Distribution ◽  
Stress Field ◽  
Stagnation Point ◽  
Analytical Solutions ◽  
Wide Spectrum ◽  
Momentum Conservation ◽  
Stagnation Point Flow ◽  
Model Parameters ◽  
Viscoelastic Models ◽  
Special Cases

Singularities in the stress field of the stagnation-point flow of a viscoelastic fluid have been studied for various viscoelastic constitutive models. Analyzing the analytical solutions of these models is the most effective way to study this problem. In this paper, exact analytical solutions of two-dimensional steady wall-free stagnation-point flows for the generic Oldroyd 8-constant model are obtained for the stress field using different material parameter relations. For all solutions, compatibility with the conservation of momentum is considered in our analysis. The resulting solutions usually contain arbitrary functions, whose choice has a crucial effect on the stress distribution. The corresponding singularities are discussed in detail according to the choices of the arbitrary functions. The results can be used to analyze the stress distribution and singularity behavior of a wide spectrum of viscoelastic models derived from the Oldroyd 8-constant model. Many previous results obtained for simple viscoelastic models are reproduced as special cases. Some previous conclusions are amended and new conclusions are drawn. In particular, we find that all models have singularities near the stagnation point and most of them can be avoided by appropriately choosing the model parameters and free functions. In addition, the analytical solution for the stress tensor of a near-wall stagnation-point flow for the Oldroyd-B model is also obtained. Its compatibility with the momentum conservation is discussed and the parameters are identified, which allow for a non-singular solution.

scholarly journals Thermoelastic analysis of FGM hollow cylinder for variable parameters and temperature distributions using FEM

2020 ◽  
Vol 9 (1) ◽  
pp. 256-264
Author(s):  
Dinkar Sharma ◽  
Ramandeep Kaur
Keyword(s):  
Stress Field ◽  
Hollow Cylinder ◽  
Numerical Study ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Functionally Graded ◽  
Gradient Index ◽  
Variable Parameters ◽  
Graded Material ◽  
Governing Differential Equation

AbstractThis paper presents, numerical study of stress field in functionally graded material (FGM) hollow cylinder by using finite element method (FEM). The FGM cylinder is subjected to internal pressure and uniform heat generation. Thermoelastic material properties of FGM cylinder are assumed to vary along radius of cylinder as an exponential function of radius. The governing differential equation is solved numerically by FEM for isotropic and anistropic hollow cylinder. Additionally, the effect of material gradient index (β) on normalized radial stresses, normalized circumferential stress and normalized axial stress are evaluated and shown graphically. The behaviour of stress versus normalized radius of cylinder is plotted for different values of Poisson’s ratio and temperature. The graphical results shown that stress field in FGM cylinder is influenced by some of above mentioned parameters.

Simulation of Stress Distribution and Mechanical Response of Metallic Glasses

1998 ◽  
Vol 554 ◽  
Author(s):  
Y. Kogure ◽  
M. Doyama
Keyword(s):  
Stress Distribution ◽  
Metallic Glasses ◽  
Mechanical Response ◽  
Local Density ◽  
Glassy State ◽  
Dynamics Simulation ◽  
Single Atom ◽  
Atomic Interaction ◽  
Embedded Atom ◽  
Embedded Atom Method Potential

AbstractMolecular dynamics simulation of the metallic glasses has been done. The embedded atom method potential function for copper is used to express the atomic interaction. The stress distribution in the glassy state is evaluated from specific volume occupied by single atom and local density in divided cells. The displacements of individual atom under the shear stress are calculated and the correlation between the displacements and the atomic volumes are investigated.

Sign in / Sign up

Export Citation Format

Share Document