Different Attempt to Improve Friction Stir Brazing: Effect of Mechanical Vibration and Rotational Speed

Behrouz Bagheri,Mahmoud Abbasi,Farzaneh Sharif,Amin Abdollahzadeh 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.9

A developed version of friction stir brazing (FSB) entitled friction stir vibration brazing (FSVB) was presented to fabricatelow carbon steel joint using %67wt Sn-%33wt Pb alloy as a braze metal. This attempt aims to analyze the role of mechanicalvibration and rotational speed on microstructure and mechanical behaviors of the brazed samples. Furthermore, the thermalanalysis, the thickness of intermetallic compounds (IMCs) layers, and void volume percentage at the joint interface werestudied. It was concluded that the temperature during the joining process increased and the coherency of the joint interfaceenhanced while FSVB was applied instead of FSB. In addition, the grains in the joint zone under the FSVB process weresmaller than those produced under the conventional FSB process. The results also showed that the mechanical performance,namely hardness, and shear strength increased and the thickness of the IMCs layer along with the void volume percentagein the brazed sample decreased as rotational speed increased from 850 to 1150 rpm. The results indicated that rotationalspeeds over 1150 rpm had detrimental effects on mechanical properties. This is related to the effect of high heat input andinduced temperature on brazing flow and filler-base metal interaction.

Investigating the Effect of Surface Roughness Size and Shape on the Nanofluid Behavior and Nanoparticles Aggregation in a Square Nanochannel by Molecular Dynamics Simulation

Bagheri Motlagh Mohammad,Kalteh Mohammad,Srinivasan Seshasai 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.5

In this article, the eff ect of surface roughness size and shape on the Poiseuille fl ow of Ar–Cu nanofl uid in a square copper nanochannel is investigated. To do this, hemispherical, cubic, semi-cylindrical roughness, shapes extended along the nanochannel length and width, and square protrusions extended along the nanochannel length and width are studied. The simulations are carried out using the molecular dynamics method and LAMMPS software. The results show that the roughness causes a change in the velocity and structure of nanofl uid atoms in the nanochannel. For example, the hemispherical roughness with a height of 7.5Å causes 24% decrease in the nanofl uid velocity. Also, the results show that the eff ect of diff erent shapes and sizes of roughness on the nanofl uid behavior is diff erent. For example, at the same height of roughness ( 7.5Å ), the velocity diff erence created by diff erent roughness shapes is around 0.208 Å ps , which is around 13% of the nanofl uid velocity in the smooth state. Additionally, it is found that the roughness makes the nanofl uid velocity profi le fl atter in the central part of the nanochannel. Also, the results reveal that the shape and height of the roughness have an eff ect on the aggregation time of nanoparticles and on how they move in the nanofl uid. Specifi cally, increasing the height of the roughness and decreasing the velocity of the nanofl uid, decreases the accumulation time of nanoparticles.

Evaluation of the Effect of Geometry on the Capacity Behavior of Tripod Bucket Foundation

Bagheri, Pouyan(벅게리 푸연),Son, Su Won(손수원),Yoon, Jong Chan(윤종찬),Kim, Jin Man(김진만) 대한토목학회 2018 대한토목학회 학술대회 Vol.2018 No.10

Using Hybrid Wavelet Approach and Neural Network Algorithm to Forecast Distribution Feeders

Bagheri Mehdi,Zadehbagheri Mahmoud,Kiani Mohammad Javad,Zamani Iman,Nejatian Samad 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

In this paper, using an algorithm based on the combination of data based on neural network virology and bacterial nutrition algorithm, improves the performance of the neural network prediction method. Also, the selection of two types of downstream and upstream filters in the wavelet transformation increases the predictive efficacy of neurological prediction. Based on the results, the optimized clustered neural network method has a more favorable response than the other methods. By selecting the appropriate filter and multichannel processing method, the maximum error percentage has improved by 15%. However, compared to the neural network prediction method, the proposed method has more computational volume due to the use of wavelet transform and also three times the use of neural prediction. Due to the large number of layers and used neurons, the neural network method has a much higher computational volume than the linear prediction method, where the linear prediction method has a higher error than the proposed method depending on the data used for training.

Investigation of the load-bearing capacity of suction caissons used for offshore wind turbines

Bagheri, Pouyan,Son, Su Won,Kim, Jin Man Elsevier 2017 Applied ocean research Vol.67 No.-

<P><B>Abstract</B></P> <P>This paper presents the results of three-dimensional finite element analyses of the suction bucket foundation used for offshore wind turbines. The behavior of the bucket and the response of soil supporting the bucket in dense and medium dense sandy soils subjected to static horizontal load are investigated. Field tests results and a centrifuge model test are used to validate the numerical model. Dimensionless horizontal load-displacement and overturning moment-rotation relationships are derived utilizing the Power law and Buckingham’s theorem. The results show good agreement between the numerical analysis results and the straight lines obtained from the Power law until a specific value of horizontal load and overturning moment. Regarding stress behavior of soil supporting the bucket, due to soil densification and bucket movement, maximum stresses are seen near the bucket tip at the right inside of the bucket. The major part of the applied load is transferred by the bucket skirt. Numerical analysis modeling results show that the bucket rotation and displacement are highly dependent on the bucket geometry and soil properties in addition to loading conditions. Normalized equations and figures for the ultimate horizontal load and overturning-moment capacities are presented and can be used for the preliminary design of the bucket foundations in sandy soils.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Preliminary design equations and figures for bucket foundations are proposed. </LI> <LI> Presenting normalized equations and figures for bucket foundations using Power law. </LI> <LI> Bucket rotation and displacement are highly dependent on the bucket geometry. </LI> <LI> Maximum stresses are seen near the bucket tip at the right inside of the bucket. </LI> <LI> The largest soil displacement occurs near the lid inside of the bucket. </LI> </UL> </P>

177Lu-EDTMP radiation absorbed dose evaluation in man based on biodistribution data in Wistar rats

Bagheri Reza 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.1

Skeletal metastases are common in patients suffering from various primary cancers. Radiopharmaceuticals are an effective option for bone pain palliation. In this work, the radiation absorbed dose of 177Lu- EDTMP radiopharmaceutical was estimated for adult man based on biodistribution data in Wistar rats. The MIRD dose calculation method and the Sparks and Aydogan methodology were applied. The results shows that about 46% of injected activity is cumulated on the surface of the trabecular and cortical bones. Radiation absorbed doses of red bone marrow and osteogenic cells were estimated to about 1.1 and 6.2 mGy/MBq, respectively. The maximum administrated activity was obtained 27 MBq/kg of body weight with an effective dose of 0.23 mSv/MBq. The results were compared with other available data from literature. This study indicated that 177Lu-EDTMP provides therapeutic efficacy for achieving bone pain palliation with low undesired dose to other normal organs.

Cyclic behavior assessment of the tripod bucket foundation

Bagheri, Pouyan,Son, Su Won,Kim, Jin Man 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10

The effect of impact with adjacent structure on seismic behavior of base-isolated buildings with DCFP bearings

Bagheri, Morteza,Khoshnoudiana, Faramarz Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.2

Since the isolation bearings undergo large displacements in base-isolated structures, impact with adjacent structures is inevitable. Therefore, in this investigation, the effect of impact on seismic response of isolated structures mounted on double concave friction pendulum (DCFP) bearings subjected to near field ground motions is considered. A non-linear viscoelastic model of collision is used to simulate structural pounding more accurately. 2-, 4- and 8-story base-isolated buildings adjacent to fixed-base structures are modeled and the coupled differential equations of motion related to these isolated systems are solved in the MATLAB environment using the SIMULINK toolbox. The variation of seismic responses such as base shear, displacement in the isolation system and superstructure (top floor) is computed to study the impact condition. Also, the effects of variation of system parameters: isolation period, superstructure period, size of seismic gap between two structures, radius of curvature of the sliding surface and friction coefficient of isolator are contemplated in this study. It is concluded that the normalized base shear, bearing and top floor displacement increase due to impact with adjacent structure. When the distance between two structures decreases, the base shear and displacement increase comparing to no impact condition. Besides, the increase in friction coefficient difference also causes the normalized base shear and displacement in isolation system and superstructure increase in comparison with bi-linear hysteretic behavior of base isolation system. Totally, the comparison of results indicates that the changes in values of friction coefficient have more significant effects on 2-story building than 4- and 8-story buildings.

Structural damage identification of plates based on modal data using 2D discrete wavelet transform

Bagheri, A.,Ghodrati Amiri, G.,Khorasani, M.,Bakhshi, H. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.1

An effective method for detection linear flaws in plate structures via two-dimensional discrete wavelet transform is proposed in this study. The proposed method was applied to a four-fixed supported rectangular plate containing damage with arbitrary length, depth and location. Numerical results identifying the damage location are compared with the actual results to demonstrate the effectiveness of the proposed method. Also, a wavelet-based method presented for de-noising of mode shape of plate. Finally, the performance of the proposed method for de-noising and damage identification was verified using experimental data. Comparison between the location detected by the proposed method, and the plate's actual damage location revealed that the methodology can be used as an accessible and effective technique for damage identification of actual plate structures.

Weighted sum Pareto optimization of a three dimensional passenger vehicle suspension model using NSGA-II for ride comfort and ride safety

Bagheri, Mohammad Reza,Mosayebi, Masoud,Mahdian, Asghar,Keshavarzi, Ahmad 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.4

The present research study utilizes a multi-objective optimization method for Pareto optimization of an eight-degree of freedom full vehicle vibration model, adopting a non-dominated sorting genetic algorithm II (NSGA-II). In this research, a full set of ride comfort as well as ride safety parameters are considered as objective functions. These objective functions are divided in to two groups (ride comfort group and ride safety group) where the ones in one group are in conflict with those in the other. Also, in this research, a special optimizing technique and combinational method consisting of weighted sum method and Pareto optimization are applied to transform Pareto double-objective optimization to Pareto full-objective optimization which can simultaneously minimize all objectives. Using this technique, the full set of ride parameters of three dimensional vehicle model are minimizing simultaneously. In derived Pareto front, unique trade-off design points can selected which are non-dominated solutions of optimizing the weighted sum comfort parameters versus weighted sum safety parameters. The comparison of the obtained results with those reported in the literature, demonstrates the distinction and comprehensiveness of the results arrived in the present study.