فهرست مقالات s Modulus

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  1 - Determination of Material Properties Components used in FEM Modeling of Ultrasonic Piezoelectric Transducer
  Abbas Pak
  Ultrasonic transducers have found new applications such as ultrasonic assisted micromachining, micro forming, surface treatment, welding, etc. Apart from the transducer’s shape and size, the resonant frequencies and amplitude are seriously affected by materials pr چکیده کامل

  Ultrasonic transducers have found new applications such as ultrasonic assisted micromachining, micro forming, surface treatment, welding, etc. Apart from the transducer’s shape and size, the resonant frequencies and amplitude are seriously affected by materials properties used for transducer components. A further problem with the material is that their properties may vary from batch to batch and may also depend on the size of the raw stock. In this work using modal analysis, the material properties are calculated based on the frequency response method, which is more accurate than the nominal one. The finite element modelling was employed for both 2D and 3D FEM analysis to observe the behaviour of the cylindrical test rods and two sandwich-type piezoelectric transducers with the nominal frequency of 20 kHz and 30 kHz to find the validity of these properties. The obtained results showed that the modal analysis method could accurately determine the bar speed, Poisson's ratio and elastic modulus of the ultrasonic transducer components. The accuracy of this method increases by considering more vibration mode. Based on the results, obtained errors for FEM modelling of two ultrasonic transducers with the frequency of 20 kHz and 30 kHz are 0.15% and 0.33%, respectively. پرونده مقاله
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  2 - بررسی اثر قطر و دما بر روی خواص مکانیکی نانولوله های تک جداره نیترید بور با استفاده از شبیه سازی دینامیک ملکولی
  محمدرضا مصطفایی عبدالحسین فریدون فریدون مسعود درویش گنجی
  شبیه سازی دینامیک ملکولی جهت محاسبه خواص مکانیکی نانولوله های تک جداره نیترید بور بکار رفته است.اثر قطر،کایرالیتی و دما بر روی خواص مکانیکی مجموعه مدنظر تخمین زده شده است.نتایج نشان می دهد که نانولوله های نیترید بور زیگزاگ مستحکم تر از نوع آرمیچر در محدوده قطر مشابه هست چکیده کامل

  شبیه سازی دینامیک ملکولی جهت محاسبه خواص مکانیکی نانولوله های تک جداره نیترید بور بکار رفته است.اثر قطر،کایرالیتی و دما بر روی خواص مکانیکی مجموعه مدنظر تخمین زده شده است.نتایج نشان می دهد که نانولوله های نیترید بور زیگزاگ مستحکم تر از نوع آرمیچر در محدوده قطر مشابه هستند.همچنین مدول یانگ هر دو نوع نانولوله تک جداره نیترید بور تا قطر مشابهی افزایش داشته و بعد از آن بطور محسوسی کاهش می یابد.ما پی بردیم که تغییرات قطرتاثیر محسوسی بر روی تنش و کرنش نهایی نانولوله های زیگزاگ ندارد.علاوه بر این نتایج نشان میدهد که تمام خواص مکانیکی محاسبه شده با افزایش دما کاهش می یابد.یافته های شبیه سازی ما نه تنها درک کلی ملکولی از نانولوله های نیترید بور را می دهد،بلکه می تواند جهت مهندسین مکانیک و پژوهشگرانی که در زمینه توسعه خواص مکانیکی فعالیت دارند،مفید واقع شود. پرونده مقاله
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  3 - شبیه سازی اتمی بررسی اثر قطر، تعداد دیواره،فاصله بین لایه ای و دما بر روی خواص مکانیکی نانولوله های چند جداره نیترید بور
  محمدرضا مصطفایی علایی عبدالحسین فریدون مسعود درویش گنجی
  به کمک استفاده از شبیه سازی دینامیک ملکولی، خواص مکانیکی نانولوله های تک جداره،دوجداره و سه جداره نیترید بور محاسبه شده است. اثر قطر،کایرالیتی،فاصله بین لایه‌ای و دما بر روی خواص مکانیکی مجموعه مدنظر تخمین زده شده است.نتایج نشان می دهد که نانولوله های نیترید بور زیگزاگ چکیده کامل

  به کمک استفاده از شبیه سازی دینامیک ملکولی، خواص مکانیکی نانولوله های تک جداره،دوجداره و سه جداره نیترید بور محاسبه شده است. اثر قطر،کایرالیتی،فاصله بین لایه‌ای و دما بر روی خواص مکانیکی مجموعه مدنظر تخمین زده شده است.نتایج نشان می دهد که نانولوله های نیترید بور زیگزاگ مستحکم تر از نوع آرمیچر در محدوده قطر مشابه هستند.همچنین مدول یانگ هر دو نوع نانولوله دوجداره و سه جداره نیترید بور با افزایش قطر،افزایش می‌یابد..علاوه بر این مدول یانگ نانولوله های نیترید بور دو جداره کوچکتر از سه جداره و بزرگتر از تک جداره می‌باشد. ما نشان دادیم که مدول یانگ نانولوله‌های دوجداره نیترید بور با تعداد لایه مختلف افزایش می‌یابد در زمانیکه فاصله بین لایه‌ای کاهش یابد. یافته‌های شبیه‌سازی ما نه تنها درک کلی ملکولی از نانولوله‌های نیترید بور را می‌دهد،بلکه می تواند جهت مهندسین مکانیک و پژوهشگرانی که در زمینه توسعه خواص مکانیکی فعالیت دارند،مفید واقع شود. پرونده مقاله
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  4 - بررسی اثرسایزصفحه گرافن و دما و طول گردن برروی خواص مکانیکی نانو غنچه گرافن با استفاده از شبیه سازی دینامیک مولکولی
  مرجان خراسانی عبدالحسین فریدون
  کربن دارای آرایش های متعددی است. نانو غنچه گرافن از تازه ترین آلوتروپ های کربن است و هنوز به صورت آزمایشگاهی در دسترس نیست. نانو غنچه گرافن از اتصال فولرن و صفحه گرافن به هم تشکیل می شود. شبیه سازی دینامیک مولکولی جهت محاسبه خواص مکانیکی نانو غنچه گرافن استفاده شده است. چکیده کامل

  کربن دارای آرایش های متعددی است. نانو غنچه گرافن از تازه ترین آلوتروپ های کربن است و هنوز به صورت آزمایشگاهی در دسترس نیست. نانو غنچه گرافن از اتصال فولرن و صفحه گرافن به هم تشکیل می شود. شبیه سازی دینامیک مولکولی جهت محاسبه خواص مکانیکی نانو غنچه گرافن استفاده شده است.اثر دما و سایز صفحه گرافن و طول گردن در این مجموعه تخمین زده شده است. نتایج نشان میدهد که تا دمای 800 کلوین مدول یانگ تغییرات کمی را با افزایش دما تجربه می کندبه عبارت دیگر با افزایش دما مدول یانگ تغییر چندانی نمی کند و تنها کمی کاهش می یابد. مشاهده شد که در یک دمای ثابت با افزایش سایز صفحه گرافن مدول یانگ نیز افزایش می یابد .یافته های شبیه سازی ما نه تنها درک کلی از نانو غنچه گرافن را افزایش می دهد بلکه می تواند جهت استفاده مهندسین و پژوهشگرانی که در زمینه توسعه خواص مکانیکی کار می کنند نیز مورد استفاده قرار گیرد. پرونده مقاله
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  5 - The Molecular Mechanics Model of Carbon Allotropes
  Mohsen Motamedi AMIRHOSSEIN NAGHDI
  10.22034/jna.2017.543209.1030
  Due to its valency, carbon can form too many allotropes. A number of well-known forms of carbon include graphene, carbon nanotubes, capped carbon nanotubes, buckyballs, and nanocones. The remarkable mechanical properties of these carbons have attracted researchers. Nume چکیده کامل

  Due to its valency, carbon can form too many allotropes. A number of well-known forms of carbon include graphene, carbon nanotubes, capped carbon nanotubes, buckyballs, and nanocones. The remarkable mechanical properties of these carbons have attracted researchers. Numerous studies have been conducted on carbon nanotubes or graphene. In the present study, however, we applied the molecular mechanic method in order to model five forms of carbon with a uniform approach and draw a detailed comparison between the allotropes of carbon. Furthermore, we obtained Young’s modulus and natural frequencies for every form of carbon, which can be useful for researchers. The results show that increasing the diameter of the carbon nanotube will decrease its strength (decreases the Young’s modulus). Also, the capped carbon nanotube is stronger than the non-capped nanotube. This is because of the end bonds of the carbon nanotube. Also, the results show that Buckyball has extraordinary properties. Its strength is three times more than that of the carbon nanotube with the same diameter. پرونده مقاله
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  6 - Stress-strain behavior of two-layer graphene with different chirality
  Mohsen Motamedi Amirhossein Aghili
  10.22034/jna.2020.1904370.1219
  Graphene is a two-dimensional sheet containing carbon atoms arranged as a honeycomb lattice. Graphene has been recently the subject of much interest due to its unique mechanical, thermal, and electrical properties. The experimental method for calculating the mechanical چکیده کامل

  Graphene is a two-dimensional sheet containing carbon atoms arranged as a honeycomb lattice. Graphene has been recently the subject of much interest due to its unique mechanical, thermal, and electrical properties. The experimental method for calculating the mechanical properties of graphene is complex because of its nanoscale lateral dimension, so the use of the theoretical method for calculating the properties of monolayer graphene has also received much attention recently.In this study, two-layer graphene with two different chirality angles was modeled by molecular dynamics in LAMMPS software. In summary, this research involves producing the primary structure, balancing the sample, applying the axial tensile test, and extracting the stress-strain graph from the sample. The simulated graphene has a value of 102.2*100.8 Å and an interlayer distance is 3.4 Å.The results showed that as the number of sheets increased, the amount of Young's modulus was more than that of the single-layer graphene. In addition, the fracture strength of the two-layer armchair graphene is greater than the fracture strength of the two-layer zigzag graphene. Then, by increasing the chirality angle, the fracture strength decreases. Finally, it was shown that by increasing the chirality angle in two-layer graphene from 0 ° (armchair) to 30 ° (zigzag), the Young's modulus value increases, while by increasing the chirality angle in single-layer graphene from 0 ° to 30 °, the Young's modulus does not change significantly. پرونده مقاله
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  7 - Stress-strain behavior of two-layer graphene with different chirality
  Mohsen Motamedi A.H. Aghili
  10.22034/jna.2021.681549
  Graphene is a two-dimensional sheet containing carbon atoms arranged as ahoneycomb lattice. Graphene has been recently the subject of much interest dueto its unique mechanical, thermal, and electrical properties. The experimentalmethod for calculating the mechanical pro چکیده کامل

  Graphene is a two-dimensional sheet containing carbon atoms arranged as ahoneycomb lattice. Graphene has been recently the subject of much interest dueto its unique mechanical, thermal, and electrical properties. The experimentalmethod for calculating the mechanical properties of graphene is complexbecause of its nanoscale lateral dimension, so the use of the theoretical methodfor calculating the properties of monolayer graphene has also received muchattention recently.In this study, two-layer graphene with two different chirality angles was modeledby molecular dynamics in LAMMPS software. In summary, this research involvesproducing the primary structure, balancing the sample, applying the axial tensiletest, and extracting the stress-strain graph from the sample. The simulatedgraphene has a value of 102.2*100.8 Å and an interlayer distance is 3.4 Å.The results showed that as the number of sheets increased, the amount ofYoung's modulus was more than that of the single-layer graphene. In addition,the fracture strength of the two-layer armchair graphene is greater than thefracture strength of the two-layer zigzag graphene. Then, by increasing thechirality angle, the fracture strength decreases. Finally, it was shown that byincreasing the chirality angle in two-layer graphene from 0 ° (armchair) to 30 °(zigzag), the Young's modulus value increases, while by increasing the chiralityangle in single-layer graphene from 0 ° to 30 °, the Young's modulus does notchange significantly پرونده مقاله
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  8 - The Molecular Mechanics Model of Carbon Allotropes
  Mohsen Motamedi Amirhossein Naghdi
  10.22034/jna.2017.540019
  Carbon can form numerous allotropes because of its valency. Graphene, carbon nanotubes,capped carbon nanotubes, buckyballs, and nanocones are well-known polymorphs of carbon.Remarkable mechanical properties of these carbon atoms have made them the subject of intenserese چکیده کامل

  Carbon can form numerous allotropes because of its valency. Graphene, carbon nanotubes,capped carbon nanotubes, buckyballs, and nanocones are well-known polymorphs of carbon.Remarkable mechanical properties of these carbon atoms have made them the subject of intenseresearch. Several studies have been conducted on carbon nanotubes or graphene. In the presentstudy, the molecular mechanics method was applied to model five polymorphs of carbon witha uniform approach and compare the allotropes of carbon in detail. Also, we obtained Young’smodulus and natural frequencies for every form of carbon, which can be useful for researchers.We found that an increase in the diameter of the carbon nanotube would accompany with adrop in its strength and Young’s modulus. Moreover, our results show that the capped carbonnanotube has a higher strength compared to that of the non-capped nanotube, which might bedue to the end bonds of the carbon nanotube. Finally, we identified extraordinary properties ofBuckyball including its strength, which is three times more than that of the carbon nanotubewith the same diameter پرونده مقاله
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  9 - Ab-initio Investigation of Mechanical Properties of MX2(M=Zr, Hf; X=S, Se, Te) Transition Metal Dichalcogenides Nano Tubes (TMDNTs)
  Abdollah Haji Malekkheili Mojtaba Yaghoubi Alireza Amani
  Miniaturization of bulk crystals in any direction down to nanometer dimensions leads to the emergence of quantum confinement phenomenon, which is technologically favorable. Transition Metal Dichalcogenides (TMDs) are important mechanical materials that have a layered st چکیده کامل

  Miniaturization of bulk crystals in any direction down to nanometer dimensions leads to the emergence of quantum confinement phenomenon, which is technologically favorable. Transition Metal Dichalcogenides (TMDs) are important mechanical materials that have a layered structure. In addition, ach layer consists of three atomic layers. TMD Nano Tubes (TMDNTs) can be created by rolling such a layer. This study investigates structural, mechanical, and bonding properties of TMDNTs. In particular, two important quantities, Young’s modulus and Poisson’s ratio, are calculated for 6 zigzag MX2 (M=Zr, Hf; X=S, Se, Te) nanotubes and the results are compared with those of other known nanotubes. The computed value of Young’s modulus is greater than that of blue Phosphorus and, in some cases, higher than those of WS2 nanotubes (which are experimentally synthesized). Given the increase in the bond length between M and X atoms, the ratio of Young’s modulus to Poisson’s increases as the atomic number X is reduced. However, there is no significant difference in the aforementioned quantity for ZrX2 and HfX2 nanotubes due to the close bond lengths of Zr-X and Hf-X. The band gap confirms this finding. A Mulliken charge analysis was conducted to investigate the amount of charge transfer between M and X atoms to observe the strength of bond lengths. پرونده مقاله
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  10 - Mechanical properties of sago starch film incorporated with phycocyanin extract of Spirulina platensis
  Fatemeh Sadeghi Erimi Masoumeh Hosseinzadeh Sadegh Salmanpour
  The mechanical and barrier properties of sago starch film incorporated with different percentage of phycocyanin(0.2, 0.4, 0.6, 0.8 and 1.0) were evaluated. With regard to mechanical properties, tensile strength and Youngs modulusdecreased when the percentage of extract چکیده کامل

  The mechanical and barrier properties of sago starch film incorporated with different percentage of phycocyanin(0.2, 0.4, 0.6, 0.8 and 1.0) were evaluated. With regard to mechanical properties, tensile strength and Youngs modulusdecreased when the percentage of extract Elongation at break (%) increased. and increased with increasing percentage ofextract from 0.2 to 0.1. پرونده مقاله
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  11 - Synthesis of polymer matrix nanocomposite with carbon fibers and analysis of its strength properties
  S.M.M. Shafiei
  In polymer-based nanocomposites, carbon nanofibers have been used to improve mechanical properties in various applications. In this research, the tensile properties of carbon nanofibers have been used to create carbon-epoxy nanocomposite and improve the mechanical prope چکیده کامل

  In polymer-based nanocomposites, carbon nanofibers have been used to improve mechanical properties in various applications. In this research, the tensile properties of carbon nanofibers have been used to create carbon-epoxy nanocomposite and improve the mechanical properties of epoxy nanocomposite, and the effect of the weight percentage of carbon nanofibers on the mechanical properties of epoxy nanocomposite has been investigated. Epoxy with weight percentages of 1.0, 5.0 and 1.5 carbon nanofibers were produced and their mechanical properties were investigated. The results showed that the use of even a small percentage of carbon nanofibers can lead to the improvement of mechanical properties. پرونده مقاله