Microstructural Investigation and High Temperature Mechanical Behavior of AXE622 Cast Mg Alloy

A. Habibi Eftekhar,S. Mohsen Sadrossadat,M. Reihanian 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5

The microstructure and high temperature properties of the AXE622 Mg alloy were investigated after the conventional andsemisolid casting processes. The tensile test was conducted at room temperature, and 473 K. Impression creep test was performedat a temperature range of 423–498 K under the stress range of 450–600 MPa. The microstructure of the conventionaland semisolid alloys contains α-Mg dendrites, the eutectic phase, secondary phases including (Mg–Al)2Ca, eutectic Mg17Al12,and Al11RE3. During semisolid processing, coarse dendrites of the α-Mg became fine, globular, and Rosetta shape. Theaverage length of the secondary phases in the semisolid alloy decreased from 4.21 to 2 μm and the average grain size of theα-Mg reduced from 113 to 96 μm. Semisolid processing caused a significant improvement in the tensile and creep resistanceof the AXE622 Mg alloy. The stress exponent for creep was calculated in the range 5.6–7.7 for the conventional alloy andin the range 10.3–11 for the semisolid alloy. The activation energy for conventional and semisolid alloy was determined as71.4 kJ/mol and 78.3 kJ/mol, respectively. It was concluded that the dominant creep mechanism in the conventional alloywas the grain boundary diffusion-controlled dislocation climb, while in the semisolid alloy was the power-law breakdown.

Development of optimum design curves for reinforced concrete beams based on the INBR9

Alireza Habibi,Fouad Ghawami,Mohammad S. Shahidzadeh 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.18 No.5

Structural optimization is one of the most important topics in structural engineering and has a wide range of applicability. Therefore, the main objective of the present study is to apply the Lagrange Multiplier Method (LMM) for minimum cost design of singly and doubly reinforced rectangular concrete beams. Concrete and steel material costs are used as objective cost function to be minimized in this study, and ultimate flexural strength of the beam is considered to be as the main constraint. The ultimate limit state method with partial material strength factors and equivalent concrete stress block is used to derive general relations for flexural strength of RC beam and empirical coefficients are taken from topic 9 of the Iranian National Building Regulation (INBR9). Optimum designs are obtained by using the LMM and are presented in closed form solutions. Graphical representation of solutions are presented and it is shown that proposed design curves can be used for minimum cost design of the beams without prior knowledge of optimization and without the need for iterative trials. The applicability of the proposed relations and curves are demonstrated through two real life examples of SRB and DRB design situations and it is shown that the minimum cost design is actually reached using proposed method.

Reliability of Steel Cylindrical Pressure Vessel Dividers in the Presence of Corrosion: Experiment and Simulation

N. Habibi,S. Mohammadi,H. Ghafary 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2

The Monte Carlo simulation method can easily provide an accurate estimate of the probability of failure. However, for complex engineering problems with a low probability of failure, it may be inappropriate to provide an inefficient estimate of the probability of failure. In this study, tests investigations were performed on pressure vessel separator plates made of marine steel A36 ASTM, which exhibited corrosion on all plates, and occurred during multiple operations. The results of the tensile tests show that the areas of fracture of the specimens were observed as follows: near the gage, in the allowable area, on the line of the gage, and outside. The data obtained here provide a quantitative understanding and benchmark of the tensile behavior of corroded plates. Strain energy and maximum force varied in corrosion rate ( ) between 10 and 24 fluctuated, while for > 24 decreased significantly. A series of simulations based on the Monte Carlo method was performed to determine the effects of corrosion rate and thickness variance on the overall behavior. The results of the two methods show that the values of the mechanical properties of the corroded specimens are scattered and follow a statistically normal distribution.

Synthesis of CuO/ ZnO Nanoparticles and Their Application for Photocatalytic Degradation of Lidocaine HCl by the Trial-and-error and Taguchi Methods

M. Giahi,N. Badalpoor,S. Habibi,H. Taghavi 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.7

A novel sol-gel method was implied to prepare CuO-doped ZnO nanoparticles. XRD and SEM techniques were used to characterize the CuO-doped ZnO sample. The photocatalytic degradation of Lidocaine HCl was investigated by two methods. The degradation was studied under different conditions such as the amount of photocatalyst, pH of the system, initial concentration, presence of electron acceptor, and presence of anions. The results showed that they strongly affected the photocatalytic degradation of Lidocaine HCl. The photodegradation efficiency of drug increased with the increase of the irradiation time. After 6 h irradiation with 400-W mercury lamp, about 93% removal of Lidocaine HCl was achieved. The degree of photodegradation obtained by Taguchi method compatible with the trial-and-error method showed reliable results.

Synthesis of CuO/ZnO Nanoparticles and Their Application for Photocatalytic Degradation of Lidocaine HCl by the Trial-and-error and Taguchi Methods

Giahi, M.,Badalpoor, N.,Habibi, S.,Taghavi, H. Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.7

A novel sol-gel method was implied to prepare CuO-doped ZnO nanoparticles. XRD and SEM techniques were used to characterize the CuO-doped ZnO sample. The photocatalytic degradation of Lidocaine HCl was investigated by two methods. The degradation was studied under different conditions such as the amount of photocatalyst, pH of the system, initial concentration, presence of electron acceptor, and presence of anions. The results showed that they strongly affected the photocatalytic degradation of Lidocaine HCl. The photodegradation efficiency of drug increased with the increase of the irradiation time. After 6 h irradiation with 400-W mercury lamp, about 93% removal of Lidocaine HCl was achieved. The degree of photodegradation obtained by Taguchi method compatible with the trial-and-error method showed reliable results.

Optimal architecture of heat generating pieces in a fin

Mohammad Reza Hajmohammadi,Sadegh Poozesh,S. Salman Nourazar,Ali Habibi Manesh 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4

This paper documents the optimal architecture of heat generating pieces connected to and cooled in a circular-shaped fin. Relying on the constructal theory, the optimal distribution of multiple heat sources is obtained by minimizing the thermal resistance of the fin. Since the heat sources are contemplated as electronic devices with uniform heat generation, the minimization of the thermal resistance is indicated by minimization of the hot spot (peak) temperature. Temperature fields in the fin and in the heat sources are calculated using a finite elements approach of MATLAB PDE toolbox. Comparison among the considered configurations reveals that the regular configurations of the heat sources commonly used in cooling industry are not optimal and must be avoided. Optimal configurations such as triangular arrangement of heat sources are proposed to replace the unfavorable configurations.

Artificial neural network optimization for removal of hazardous dye Eosin Y from aqueous solution using Co2O3-NP-AC: Isotherm and kinetics study

P. Assefi,M. Ghaedi,A. Ansari,M.H. Habibi,M.S. Momeni 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

The present research is focused on the synthesis and characterization of cobalt (III) oxide (Co2O3) nanoparticle loaded on activated carbon to prepare an outstanding sorbent for the removal of eosin Y (EY) as hazardous dye from aqueous solution. The sorbent was identified by SEM and XRD analysis. The effect of solution pH, adsorbent dosage (0.005–0.02 g), contact time (0.5–30 min) and initial eosin Y concentration (30–80 mg L-1) on the adsorption process was investigated and modeled by artificial neural network. Following optimization of variables, the experimental equilibrium data was analysis by Langmuir, Freundlich, Tempkin and D–R isothermal models and explored that the data well presented by Langmuir model with a maximum adsorption capacity of 555.56 mg g-1 at 25 ℃. Kinetic studies at various adsorbent dosage and initial EY concentrations show that high removal percentage (>90%) was achieved within 15 min of the start of every experiment at most conditions. The adsorption of EY follows the pseudo-second-order rate equation in addition to intraparticle diffusion model. The experimental data were applied to train the multilayer feed forward neural network with three inputs and one output with different algorithms and different numbers of neurons in the hidden layer. The minimum mean squared error (MSE) of 1.49e 04 and determination coefficient of (R2) 0.9991.