فهرست مقالات Semi-Elliptical Crack

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  1 - Fatigue Crack Growth in Thin-Wall Pipes Subjected to Bending
  MohammadMahdi Amiri
  In this paper, a circumferential external surface flaw in a metallic round pipe under cyclic bending loading is considered. Because of very rapid changes in the geometrical parameters around the crack front region, the mesh generation of this region must be done with gr چکیده کامل

  In this paper, a circumferential external surface flaw in a metallic round pipe under cyclic bending loading is considered. Because of very rapid changes in the geometrical parameters around the crack front region, the mesh generation of this region must be done with great care. The analysis of the fatigue crack growth is done in accordance with Paris law. The spread lane of the exterior defect is achieved from the graph of “α” vs. “relative crack depth”. The growth of fatigue crack is also analyzed (the comparative crack depth against loading runs diagram) with various initial crack “α” beneath periodic loading. Fatigue shape growth of primarily semi-elliptical peripheral surface flaws is shown. The weight of the Paris exponent (material constant) on fatigue crack propagation is presented as well. Furthermore, the “fatigue crack growth” progression of several specimens is evaluated experimentally by employing a manually-constructed experimental setup. Conclusively, the experimental results achieved by periodic bending loading tests are compared with the numerical results. Fatigue shape development of initially semi-elliptical external surface defects is illustrated. The effect of the Paris exponent (material constant) on fatigue crack propagation is shown as well. Moreover, the fatigue crack growth of several specimens is assessed experimentally using a manually-constructed experimental set up. Finally, the experimental results obtained by cyclic bending loading tests are compared. پرونده مقاله
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  2 - Three-Dimensional Stress Analysis for Semi-Elliptical Cracks in the Connection of Cylinder-Hemispherical Head for Thick-Walled Cylindrical Pressure Vessels
  H Eskandari M Ghanbari F Mirzadeh
  10.22034/jsm.2020.555468.1194
  These pressure vessels are made by different type of heads. One of them is hemi-spherical head. The area of geometrical discontinuity, like the connection of the cylinder to its hemi-spherical head, are the most susceptible areas for crack initiation along their welds. چکیده کامل

  These pressure vessels are made by different type of heads. One of them is hemi-spherical head. The area of geometrical discontinuity, like the connection of the cylinder to its hemi-spherical head, are the most susceptible areas for crack initiation along their welds. So it is worthwhile to consider cracks located at this connection. The purpose of this article is to investigate the effect of variation of stress field and geometry of problem on distribution of Stress Intensity Factor (SIF) for a semi-elliptical surface crack which is located at the connection of cylinder to its hemispherical head. The three dimensional finite element analysis is performed by employing singular elements along the crack front. The ratio of crack depth to crack length (a/c) ranged from 0.3 to 1.2; the ratio of crack depth to wall thickness (a/t)ranged from 0.2 to 0.8; and the cylinder geometry parameter of vesselranged from 1.2 to 2. For better comparison the results are normalized and reported in non-dimensional formats. The results show that the crack configuration, vessel thickness and radius have significant influence on the stress intensity factor distribution along the crack front. Also For a fixed and the maximum value of SIF occur in the cylindrical part and approximately near the deepest point of crack; not on the deepest point of crack depth and this may be due to changing stress field in this connection. The stress intensity factors are presented in suitable curves for various geometrical configurations providing useful tool for the fracture mechanics design of cracked pressure vessels. پرونده مقاله
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  3 - Fracture Analysis of Externally Semi-Elliptical Crack in a Spherical Pressure Vessel with Hoop-Wrapped Composite
  H Eskandari Gh Rashed F Mirzade
  In this paper the effect of composite hoop-wrapped on stress intensity factor for semi-elliptical external crack which located in spherical pressure vessel, were investigated through the Finite Element Analysis. In order to find the effect of some parameters such as com چکیده کامل

  In this paper the effect of composite hoop-wrapped on stress intensity factor for semi-elliptical external crack which located in spherical pressure vessel, were investigated through the Finite Element Analysis. In order to find the effect of some parameters such as composite thickness and width, internal pressure and crack geometry, comparisons between different cases were done and discussed in detail. The result show that repairing crack with composite hoop-wrapped, can significantly reduce the stress intensity factor along the crack front. پرونده مقاله
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  4 - Ductile Failure and Safety Optimization of Gas Pipeline
  P Zamani A Jaamialahmadi M Shariati
  Safety and failure in gas pipelines are very important in gas and petroleum industry. For this reason, it is important to study the effect of different parameters in order to reach the maximum safety in design and application. In this paper, a three dimensional finite e چکیده کامل

  Safety and failure in gas pipelines are very important in gas and petroleum industry. For this reason, it is important to study the effect of different parameters in order to reach the maximum safety in design and application. In this paper, a three dimensional finite element analysis is carried out to study the effect of crack length, crack depth, crack position, internal pressure and pipe thickness on failure mode and safety of API X65 gas pipe. Four levels are considered for each parameter and finite element simulations are carried out by using design of experiments (DOE). Then, multi-objective Taguchi method is conducted in order to minimize x and y coordinates of Failure Assessment Diagram (FAD). So, desired levels that minimize the coordinates and rises the possibility of safety are derived for each parameter. The variation in FAD coordinates according to the changes in each parameter are also found. Finally, comparisons between the optimum design and all other experiments and simulations have shown a good safety situation. It is also concluded that the more design parameters close to optimum levels, the better safety condition will occur in FAD. A verification study is performed on the safety of longitudinal semi-elliptical crack and the results has shown a good agreement between numerical and experimental results. پرونده مقاله
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  5 - Fracture analysis of conical shells containing an internal semi-elliptical crack
  C. Burvill M.M. Kheirikhah S. Omidi S. Gohari
  Conical shells play a significant role in different branches of engineering such as aerospace and oil industries. The purpose of this paper is to analyze the fracture behavior of metallic conical shells containing an internal semi-elliptical crack. An accurate three-dim چکیده کامل

  Conical shells play a significant role in different branches of engineering such as aerospace and oil industries. The purpose of this paper is to analyze the fracture behavior of metallic conical shells containing an internal semi-elliptical crack. An accurate three-dimensional finite element method is employed to model the conical shell using ANSYS standard code. Special singular elements are used to consider the square-root singularity at the semi-elliptical crack front. Stress intensity factors of the cracks which placed in different positions of the shell is calculated. To confirm the accuracy of the present finite element model, both stress distribution of the structure and stress intensity factor of the crack in special case are compared with published results. The effect of different geometrical parameters on the stress intensity factor of the cracks are investigated. Results show that the crack aspect ratio has a significant effect on the stress intensity factor of the cracks. پرونده مقاله