scholarly journals Stress Analysis in Damaged Pipeline with Composite Coating

2021 ◽  
Vol 11 (22) ◽  
pp. 10676
Author(s):  
Maciej Dutkiewicz ◽  
Taras Dalyak ◽  
Ivan Shatskyi ◽  
Tetyana Venhrynyuk ◽  
Andrii Velychkovych
Keyword(s):  
Composite Coating ◽  
Plane Deformation ◽  
Component Composition ◽  
Homogenization Method ◽  
Internal Crack ◽  
The Finite Element Method ◽  
Wound Composite ◽  
Axial Surface ◽  
Theory Of Shells ◽  
The Ideal

This paper studied the distribution of stresses near damage in the form of axial surface cracks in a pipeline reinforced with a spiral-wound composite coating. The authors applied the homogenization method to determine the effective elastic characteristics of a structurally anisotropic layered package. By means of the classical momentless theory of shells, it was established that the stress state of the coated intact pipe under the pressure of the pumped product depends on the parameters of the geometry of the capacity strip, as well as on the component composition of the heterogeneous coating. The finite element method was applied to solve the problem of plane deformation of a piecewise homogeneous ring with an internal crack perpendicular to the interface. This problem assumes the linearity of the materials and the ideal mechanical contact with the layers. The effect of the composite coating and the size of the damage on the magnitudes of the energy flow into the crack tip, and on the stress intensity factor, was studied in detail. Various variants of the coating were considered, namely, winding of the coating on an unloaded pipe and reinforcement of the pipe under repair pressure.

scholarly journals Simulation of a Contact Pseudo-Environment in Calculating Thermal Resistance

2021 ◽  
Vol 346 ◽  
pp. 03049
Author(s):  
Alexander Denisenko ◽  
Roman Grishin ◽  
Liubov Podkruglyak
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Method ◽  
Numerical Modeling ◽  
Thermal Resistance ◽  
Contact Zone ◽  
Metal Cutting ◽  
The Finite Element Method ◽  
Contact Thermal Resistance ◽  
Temperature Criterion ◽  
The Ideal

The use of the temperature criterion in the design of metal-cutting machines, determined on the basis of models that take into account the contact thermal resistances, is an objective necessity. These models should take into account to the maximum extent the actual conditions of contact of parts in the design under consideration, determined by the deviations of the mating surfaces from the ideal shape. The article presents the results of numerical modeling based on the finite element method of the formation of the contact thermal resistance and the evaluation of the influence of the parameters of the intermediate layer (pseudo-environment) that occurs in the contact zone of surfaces with macro-deviations on the passage of the heat flow. The obtained results allowed us to identify the most significant of the considered parameters. It is established that when modeling a pseudo-environment, it is necessary to take into account the coefficient of its thermal conductivity, the size, location and integrity of the actual contact zone.

scholarly journals Reasoning of the Model Sizes in Modeling the Interaction between Tool and Rock

2018 ◽  
Vol 41 ◽  
pp. 03002 ◽  
Author(s):  
Vladimir Aksenov ◽  
Vladimir Sadovets ◽  
Dmitriy Pashkov
Keyword(s):  
Municipal Services ◽  
The Finite Element Method ◽  
Ideal Model ◽  
Face Surface ◽  
Face Shape ◽  
The Face ◽  
Helicoidal Surfaces ◽  
Model Size ◽  
Executive Body ◽  
The Ideal

The article proves model sizes for modeling the interaction between tool and rock. The relevance of the research was considered. Information on the analysis of existing executive bodies (EB) used in mining, construction and municipal services is given. The finite element method is described, it was concluded in particular that the ideal model of the interaction of the executive body with the face rock would be a surface conjugated with the working of real dimensions located in an infinite massif or in a massif that is many times larger than the output. To solve the problem, cylindrical workings with a diameter D = 3.2 m were used, where the face shape is represented by two-thread helicoidal surfaces, surrounded by an around boundary massif with thickness B equal to 0.5D, D, 1.5D, 2D, 2.5D.The exterior surfaces of the model were fixed, and distributed loads corresponding to the interaction forces arising from the operation of the ETC-2086 bar unit installed on the basis of the MTZ-82 tractor were applied to the face surface. On the basis of the conducted research, the effect of the model size on the pattern of directed differentiated state (DDS) of a face was determined.

Wrinkling analysis and control of rectangular space membrane

2016 ◽  
Vol 231 (11) ◽  
pp. 1959-1969
Author(s):  
Mingjun Liu ◽  
Jin Huang ◽  
Yali Wang
Keyword(s):  
Control Method ◽  
Plate Theory ◽  
Plane Deformation ◽  
The Finite Element Method ◽  
Membrane Structures ◽  
Wrinkling Analysis ◽  
Out Of Plane ◽  
And Control ◽  
The Relationship ◽  
Main Factor

Wrinkling, a common phenomenon found in space membrane structures, is the main factor affecting the performance, stability, and dynamic characteristics of these membrane structures. This article presents an active control method to improve the surface accuracy of membrane structures. A model of a thin rectangular membrane subjects to uniaxial uniform tensile stress is discussed. Initially, the relationship between the out-of-plane deformation of the wrinkles and the boundary conditions is built with the Föppl–Von Karman plate theory by introducing the slow varying Fourier series. Because vertical tensions perpendicular to the direction of the initial wrinkles are necessary to reduce these wrinkles, reasonable locations and magnitudes of these tensions are the key problems. The finite element method and variational principle method are used to solve this issue. Finally, a manufacturing error is added to the model as an initial defect, and the robustness of the controller is verified. Simulation results show that wrinkles are reduced quickly and effectively with the proposed method.

Finite Element Analysis for Demolding Process in Thermal Imprint Lithography

2007 ◽  
Author(s):  
Zhichao Song ◽  
Jaejong Lee ◽  
Sunggook Park
Keyword(s):  
Finite Element ◽  
Contact Region ◽  
Substrate Surface ◽  
Mold Insert ◽  
Local Stress ◽  
Imprint Lithography ◽  
Structural Failure ◽  
The Finite Element Method ◽  
Element Analysis ◽  
The Ideal

In thermal imprint lithography, most of the imprint failures occur during demolding, a process to separate the mold insert from the substrate after conformal molding. The success of demolding is determined by the stress generated in the resist with respect to the yield stress of the resist. In this paper we simulated the demolding process in thermal imprint lithography using the finite element method to study the stress distribution and deformation in poly(methyl methacrylate) (PMMA) resist during demolding. During demolding, the stress concentrates both at the transition corner zone between the residual layer and the replicated pattern, and close to the contact region with the moving stamp. As demolding proceeds, the highest local stress for both locations shows two maximums, indicating that a structural failure may occur not only when demolding starts, but also immediately before demolding ends. The structural failure at the second maximum becomes dominant as the angular offset from the ideal normal demolding to the substrate surface increases or for the structures located far away from the symmetric centerline. In addition, we will discuss the influence of other process and geometry parameters, including demolding rate and stamp aspect ratio.

Regular papers / Articles ordinaires A numerical approach for the static analysis of the body of pressurized dry gas holders

2003 ◽  
Vol 30 (2) ◽  
pp. 381-390
Author(s):  
L H You ◽  
J J Zhang ◽  
H B Wu ◽  
R B Sun
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Plane Deformation ◽  
Numerical Approach ◽  
Gas Pressure ◽  
The Body ◽  
The Finite Element Method ◽  
Out Of Plane ◽  
Plane Bending ◽  
Element Method

In this paper, a numerical method is developed to calculate deformations and stresses of the body of dry gas holders under gas pressure. The deformations of the wall plates are decomposed into out-of-plane bending and in-plane deformation. The out-of-plane bending of the wall plates is described by the theory of orthotropic plates and the in-plane deformation by the biharmonic equation of flat plates under plane stress. The theories of beam columns and beams are employed to analyze the columns and corridors, respectively. By considering compatibility conditions between the members and boundary conditions, equations for the determination of deformations and stresses of dry gas holders under gas pressure are obtained. Both the proposed approach and the finite element method are used to investigate the deformations and stresses of the body of a dry gas holder under gas pressure. The results from the proposed method agree with those from the finite element method. Because far fewer unknowns are involved, the proposed method is computationally more efficient than both the finite element method and the series method developed from the theory of stiffened plates.Key words: numerical approach, body of dry gas holders, gas pressure.

scholarly journals Methods of diagnostic of pipe mechanical damage using functional analysis, neural networks and method of finite elements

2020 ◽  
Vol 12 (S) ◽  
pp. 79-90
Author(s):  
Elena L. KUZNETSOVA ◽  
Grigory V. FEDOTENKOV ◽  
Eduard I. STAROVOITOV
Keyword(s):  
Neural Networks ◽  
Functional Analysis ◽  
Finite Element ◽  
Measurement Data ◽  
Mechanical Damage ◽  
The Finite Element Method ◽  
Underground Structures ◽  
Geometric Problems ◽  
Intelligent Software ◽  
Theory Of Shells

The main goal of the study is to analyze methods and diagnose mechanical damage to the pipeline using functional analysis, neural networks and the finite element method. In the work, mathematical formulations of the corresponding geometrical inverse problems of the theory of shells on reconstruction of defects of lateral surface are formulated according to measurement data obtained from sensors located in a given section of the shell. The statement was given and a method for solving inverse geometric problems for a shell of Tymoshenko type was developed. The authors have offered methods for solving inverse geometric problems of identifying volumetric and crack-like defects in extended underground structures and pipelines based on the analysis of responses to unsteady elastic-wave perturbations using the mathematical apparatus of wavelet signal transformation, the finite element modeling method and intelligent software system based on neural network.

scholarly journals Strength analysis of filament-wound composite tubes

2010 ◽  
Vol 64 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Ivana Vasovic
Keyword(s):  
Finite Element ◽  
Layered Composite ◽  
Strength Analysis ◽  
The Finite Element Method ◽  
Composite Tubes ◽  
Initial Failure ◽  
Filament Wound ◽  
Commercial Code ◽  
Filament Wound Composite ◽  
Wound Composite

The subject of this work is focused on strength analysis of filament-wound composite tubes made of E glass/polyester under internal pressure. The primary attention of this investigation is to develop a reliable computation procedure for stress, displacement and initial failure analysis of layered composite tubes. For that purpose we have combined the finite element method (FEM) with corresponding initial failure criterions. In addition, finite element analyses using commercial code, MSC/NASTRAN, were performed to predict the behavior of filament wound structures. Computation results are compared with experiments. Good agreement between computation and experimental results are obtained.

scholarly journals Determination of the stressed state of thin-construction structures using the methods of the theory of shells

2017 ◽  
Vol 3 (3) ◽  
pp. 64-78
Author(s):  
Igor G Emel’yanov ◽  
Alexey V Kuznetsov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fourier Series ◽  
Strain State ◽  
Shell Theory ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Computing Power ◽  
Thin Walled ◽  
Theory Of Shells

Introduction. With the development of numerical methods and computational complexes, it is quite easy to evaluate the stress state of thin-walled structures in the form of rotation bodies. However, when solving such problems by the finite element method, it is necessary to choose such finite element grid to "grasp" all possible singularities of the stressed state. To correctly take them into account, you must reduce the size of the finite elements. Reducing the size of the elements leads to an increase in the required computing power. Formulation of the problem. When solving applied problems, even with a sufficiently coarse grid, the number of elements can exceed hundreds of thousands. When solving problems for real constructions in a three-dimensional setting, the amount of computation can be quite large and not every supercomputer can even handle such a solution. Objective. The purpose of this paper is to use the well-known approach used in shell theory, which allows us to reduce the three-dimensional problem to the solution of a onedimensional problem, which substantially reduces the requirements for computing power. Method (methodology). The problem of determining the stress state of shell structures in the form of bodies of revolution is considered. The approach is based on the integration of the equations of the theory of shells and the expansion of functions into Fourier series for separation of variables. The expansion into a discrete Fourier series in cosines and sines is used in this paper, which describes arbitrary asymmetric mechanical loads. Results. A thin-walled cylindrical structure hinged at the ends is considered. The structure is loaded in three places by a distributed force acting normal to the surface of the shell. After integrating the system of equations for the shell, the found stress-strain state of the shell is determined by the stress components on the outer and inner surfaces of the shell and the displacement components. The paper compares the calculation results with the proposed methodology and the finite element method. The conclusion. It is shown that the use of methods of shell theory, and the proposed expansion of resolving functions and loads in a Fourier series, allows solving problems using small computing resources. At the same time, the necessary accuracy of calculation for all components of the stress-strain state of the structure is ensured.

Dynamic stiffness formulation for the vibrations of stiffened plate structures with consideration of in-plane deformation

2017 ◽  
Vol 24 (20) ◽  
pp. 4825-4838 ◽  
Author(s):  
Xuewen Yin ◽  
Wenwei Wu ◽  
Kuikui Zhong ◽  
Hui Li
Keyword(s):  
Finite Element ◽  
Dynamic Stiffness ◽  
Plane Deformation ◽  
Element Model ◽  
The Finite Element Method ◽  
Plate Structures ◽  
Beam Elements ◽  
Stiffness Model ◽  
Out Of Plane ◽  
The Relationship

A dynamic stiffness method is presented for the vibrations of plate structures that are reinforced by eccentric stiffeners. The model incorporates both out-of-plane and in-plane deformations of the plates and the stiffeners. Based on the relationship between the forces and displacements along the common edges of the plate or beam elements, the dynamic stiffness formulae for the plate and the beam elements are derived, respectively. The globally assembled dynamic stiffness matrix is then obtained using the finite element method so that the dynamics of built-up stiffened plates can be readily addressed by using the present method. Compared to the conventional finite element model, the dynamic stiffness model can provide very accurate solutions using only one element over each uniform plate and beam member, regardless of its geometry.

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