List of articles (by subject)
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Open Access Article
1 - تحلیل اجزای محدود فرآیند سخت گردانی استحاله ای سطحی با استفاده از منبع حرارتی متحرک بهمراه اعمال استراتژی کنترل سرعت جهت کاهش مشکل عیوب در لبه ها
آرش خواجه سید احمد جنابعلی جهرمی حبیب دانش منش -
Open Access Article
2 - بررسی و شبیه سازی استحکام برشی اتصال چسبی در پنل های ساندویچی با هسته فوم آلومینیومی تولید شده به روش ذوبی با عامل فوم ساز
مسعود گلستانی پور ابوالفضل باباخانی سید مجتبی زبرجد -
Open Access Article
3 - Analysis of Thermo-Mechanical Behavior of Gold Nanowire by Using Molecular Dynamics Method
Mohammad Tahmasebipour Reihaneh Ahmadi Mehrzad ModarresWith the increasing growth and development of Nano science and nanotechnology, applications of the Nano-sensors, Nano-electro-mechanical systems, Nano-electric systems and Nano-photonic devices is rising day-by-day. Nanowires, as one of the key components of these syste MoreWith the increasing growth and development of Nano science and nanotechnology, applications of the Nano-sensors, Nano-electro-mechanical systems, Nano-electric systems and Nano-photonic devices is rising day-by-day. Nanowires, as one of the key components of these systems, play a significant role in their proper function. Therefore, recognition of the thermo-mechanical behavior of nanowires has a particular importance. Due to the inevitable problems in conducting empirical experiments on nanowires, including the need for highly precise and advanced equipment, as well as the high cost and time needed to carry out these experiments, a number of researchers have simulated the behavior of nanowires. Molecular dynamics simulation is one of the best methods for recognizing the properties of nanowires, which is used in most nano-scale simulations. By using simulation and modeling methods, nanowires properties can be studied at a very low cost and short time, in comparison with experimental methods. In this paper, the effect of temperature (300, 450, 600 and 700 ◦K) and strain rate (2×108, 2×109 and 2×1010 1/s) on the mechanical properties of a gold nanowire (with diameter and length of 3 and 6 nanometers, respectively) such as stress-strain curve, yield stress, stress at failure moment, and the magnitude of nanowire elongation by molecular dynamics method have been investigated to determine the thermo-mechanical behavior of the gold nanowire. Manuscript profile -
Open Access Article
4 - Finite element simulation of the effect of the second pulse current on temperature distribution and nugget size in resistance spot welding of TRIP1100 steel
Hamid Ashrafi Iman HajianniaIn this study, simulation of the effect of the second pulse current on temperature distribution and nugget size of TRIP1100 steel during resistant spot welding was performed by finite element method. Then, the effect of the second pulse current on the weld nugget size, MoreIn this study, simulation of the effect of the second pulse current on temperature distribution and nugget size of TRIP1100 steel during resistant spot welding was performed by finite element method. Then, the effect of the second pulse current on the weld nugget size, weld nugget microstructure and mechanical properties of the resistant spot welds of the above-mentioned steel was experimentally investigated. Temperature distribution, weld nugget dimensions and heating and cooling cycles during resistant spot welding were predicted by simulation. Based on the simulated thermal cycles and continuous cooling transformation diagram of the TRIP1100 steel, a fully martensitic microstructure was predicted for the weld nugget in all currents. A good agreement was obtained between the simulated and experimental results. It was observed that the nugget diameter logarithmically increases with increasing the second pulse current. Furthermore, the microstructure of weld nugget in all samples was fully martensitic. Assessment of the mechanical properties of the welded samples by shear tension test demonstrated that the maximum load increases with increasing the weld nugget diameter. Nevertheless, the fracture energy decreased with increasing the nugget diameter. Manuscript profile -
Open Access Article
5 - Investigation of the Effect of Atomic Structure Defects on the Thermal Expansion Coefficient of Zigzag and Armchair Carbon Nanotubes Using Molecular Dynamics Method
Farshid Aghadavoudi Hossein GolestanianThe mechanical and physical properties of carbon nanotubes depend on their size and atomic structure. Accurate determination of the properties of carbon nanotubes, including the coefficient of thermal expansion, has many practical problems due to the limitations of labo MoreThe mechanical and physical properties of carbon nanotubes depend on their size and atomic structure. Accurate determination of the properties of carbon nanotubes, including the coefficient of thermal expansion, has many practical problems due to the limitations of laboratory methods. In this study, molecular dynamics method has been used to investigate and extract the properties of thermal expansion coefficient in a number of samples of carbon nanotubes that have different diameters and armchair and zigzag structures. In this study, the effect of atomic structure defects including Stone–Wales and vacancy defects on the coefficient of thermal expansion and longitudinal elastic mechanical properties of carbon nanotubes have been investigated. The potential function used in COMPASS simulation. Based on the obtained results, the coefficient of thermal expansion for CNT (7,7) at a temperature of 800 K is calculated at about 6.34 , which shows a good agreement with the results of laboratory studies. Also, the presence of defects in the atomic structure, including the defect of the non-reconstructed vacancy, in most cases has increased the coefficient of thermal expansion, which has been equal to 65% in CNT (0, 7). The vacancy defect is more effective than the Stone-Walsh defect in changing the coefficient of thermal expansion. The results show that the elastic properties of the CNT case study are also weakened by 22% due to the defect of the vacancy in the longitudinal direction. Manuscript profile -
Open Access Article
6 - Investigating the Effect of Poly (D L-Lactic Acid) Molecular Weight on the Shape Memory Parameters: A Molecular Dynamics Study
Mohammad Amini Abbas MontazeriShape memory polymers are a subset of smart materials that can regain their original shape after a temporary deformation. In recent years, these polymers have been vastly utilized in many industries (especially biomedical). The main purpose of this study was to find the MoreShape memory polymers are a subset of smart materials that can regain their original shape after a temporary deformation. In recent years, these polymers have been vastly utilized in many industries (especially biomedical). The main purpose of this study was to find the influence of the polymer molecular weight on the various shape memory parameters. Additionally, the mechanisms governing the shape memory behavior of polymers are thoroughly studied. Calculating the glass transition temperature and exploring its role on the shape memory behavior of polymeric materials are the other objectives of the current research. In this study, all models were built via Materials Studio and all the simulations were carried out using LAMMPS software. Based on the obtained results, the glass transition temperature of polymer increases with increasing the degree of polymerization. The attempts made to achieve an optimal microstructure revealed that the shape fixity parameter increases from 90% to 94% with increasing the molecular weight from 36000 g/mol to 108000 g/mol. In contrast to the shape fixity, the shape recovery parameter follows a descending trend with increasing the molecular weight. This is attributed to an increase in the ratio of the fixed phase to its reversible counterpart. Manuscript profile