Mechanical Engineering
Hadi eskandari; Moslem Ghanbari
Abstract
The present study deals on the geometry effects of the spherical pressure vessel(SPV) and the crack configuration on the variation of the stress intensity factor (SIF) through the crack line. The pressurized vessel is subjected to the pressure and thermal gradient (thermo-mechanical loading). The 3D ...
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The present study deals on the geometry effects of the spherical pressure vessel(SPV) and the crack configuration on the variation of the stress intensity factor (SIF) through the crack line. The pressurized vessel is subjected to the pressure and thermal gradient (thermo-mechanical loading). The 3D analysis of defected thick-walled pressurized sphere vessel is done using the numerical Finite Element Method (FEM). This work covers a wide range of the crack configurations in vessels with different geometries. The effect of the various parameters such as thermal gradient, RO/Ri, a/c and a/t on the variation of the dominant first mode of SIF through the crack front is studied. The obtained SIF’s are compared with the mechanical loading results (in the absence of the thermal gradient). The results show that parameters such as the aspect ratio of the crack, the ratio of the crack depth, the pressure vessel wall thickness and also the temperature gradient have significant effects on the distribution of the SIF through the crack line. It can be seen that the thermo-mechanical condition is more critical.
Mechanical Engineering
Hadi eskandari
Abstract
This work pertains to investigate the values of the stress intensity factor (SIF) in a functionally graded spherical pressure vessel with an embedded surface defect (semi elliptical crack) under thermo-mechanical loading. The three dimensional finite element analysis is performed to evaluate the SIFs ...
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This work pertains to investigate the values of the stress intensity factor (SIF) in a functionally graded spherical pressure vessel with an embedded surface defect (semi elliptical crack) under thermo-mechanical loading. The three dimensional finite element analysis is performed to evaluate the SIFs through the crack front for a wide range of crack profiles and the various layer thickness. It is assumed that the elastic modulus of sphere varies exponentially in the radial direction of the vessel.The effect of non-uniform coefficient of thermal expansion (CTE) on the fracture parameters is also studied. The obtained results show that the material gradation of spherical pressure vessel can considerably affect the distribution of the SIFs along the crack front. The gradation of material, the wall thickness of spherical pressure vessel and the profile of crack front can affect the critical point through the crack front which is apt to the crack growth.
Petroleum Engineering
Hojatallah Koraee; Hadi Eskandari; Iman Danaee
Abstract
Corrosion results in hazardous and expensive damage to pipelines, vehicles, water and wastewater systems, and even home appliances. One of the most extensively practical methods for protecting metals and alloys against corrosion is to use organic inhibitors. The inhibition capability of 2-Mercaptobenzothiazole ...
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Corrosion results in hazardous and expensive damage to pipelines, vehicles, water and wastewater systems, and even home appliances. One of the most extensively practical methods for protecting metals and alloys against corrosion is to use organic inhibitors. The inhibition capability of 2-Mercaptobenzothiazole (2-MBT) against the corrosion of carbon steel in a 2 M NaCl solution was examined by Tafel polarization. By using 2-Mercaptobenzothiazole both the cathodic and anodic reactions are delayed through chemical and physical adsorption and blocking the active corrosion sites. Based on the polarization curves, it was indicated that by increasing the inhibitor concentration, the inhibition efficiency increases up to 70% at room temperature, and it improves at higher temperatures. The adsorption of 2-Mercaptobenzothiazole was based on the Langmuir adsorption isotherm. The enthalpies of activation were determined to be around +50 kJ.mol-1. The endothermic nature of the steel dissolution procedure is reflected by the positive symbols of the enthalpies (ΔH) of activation process. The determined values range from -32.69 to -35.81 kJ.mol-1, which shows both electrostatic adsorption and the chemisorption of the adsorption mechanism. The calculated entropy of adsorption was 78 J.mol-1.K-1 indicating the increment in the solvent entropy and a more positive water desorption entropy.
