فهرس المقالات FLD

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  1 - Experimental Investigation of the Formability Improvement of Brass 260 and Al5182-O in Various Strain Rate using Hydrodynamic and Electrohydraulic Forming Methods
  َAmin Ashrafi Tafreshi Mehdi Zohoor
  Studying the formability of the sheet metals have been the subject of many researches during the last decades. A number of experimental and numerical approaches were implemented to derive the formability diagrams of different materials. In this study, the formability of أکثر

  Studying the formability of the sheet metals have been the subject of many researches during the last decades. A number of experimental and numerical approaches were implemented to derive the formability diagrams of different materials. In this study, the formability of two mostly used alloys, Brass 260 and Al5182-O as low and moderate formability materials, were investigated respectively. The forming limit diagrams of both materials were determined by using three experimental approaches such as Nakazima quasi-static as low strain rate method, hydrodynamic forming method as the moderate strain rate method and Electrohydraulic Forming process as high strain rate method. Three experimental results of forming limit diagram with the various strain rate were compared graphically. The results have shown that both of the materials could withstand higher strains when the electrohydraulic forming method was applied on the specimens and consequently, the forming limit diagrams for Brass 260 and Al5182-O shift up by 11% and 14%, respectively. In addition, it was concluded that the hydrodynamic forming method improves the formability of the materials by 4% and 6% for Brass 260 and Al5182-O, respectively. The outcomes of this study indicated that the formability of both materials was improved significantly by increasing the strain rate. تفاصيل المقالة
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  2 - Multi-Objective Tabu Search Algorithm to Minimize Weight and Improve Formability of Al3105-St14 Bi-Layer Sheet
  M Ehsanifar H Momeni N Hamta A. R Nezamabadi
  10.22034/jsm.2019.1867430.1433
  Nowadays, with extending applications of bi-layer metallic sheets in different industrial sectors, accurate specification of each layer is very prominent to achieve desired properties. In order to predict behavior of sheets under different forming modes and determining أکثر

  Nowadays, with extending applications of bi-layer metallic sheets in different industrial sectors, accurate specification of each layer is very prominent to achieve desired properties. In order to predict behavior of sheets under different forming modes and determining rupture limit and necking, the concept of Forming Limit Diagram (FLD) is used. Optimization problem with objective functions and important parameters aims to find optimal thickness for each of Al3105-St14 bi-layer metallic sheet contributors. Optimized point is achieved where formability of the sheet approaches to maximum extent and its weight to minimum extent. In this paper, multi-objective Tabu search algorithm is employed to optimize the considered problem. Finally, derived Pareto front using Tabu search algorithm is presented and results are compared with the solutions obtained from genetic algorithm. Comparison revealed that Tabu search algorithm provides better results than genetic algorithm in terms of Mean Ideal Distance, Spacing, non-uniformity of Pareto front and CPU time. تفاصيل المقالة
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  3 - Theoretical, Numerical and Experimental Investigation on Formability of Al3105-St14 Two-Layer Sheet
  H Deilami Azodi R Darabi
  Two-layer metallic sheets have wide applications in various industries due to their superlative characteristics. This paper presents analytical model to investigate the formability of two-layer sheets based on Marciniak and Kuckzinsky (M-K) method using Barlat and Lian أکثر

  Two-layer metallic sheets have wide applications in various industries due to their superlative characteristics. This paper presents analytical model to investigate the formability of two-layer sheets based on Marciniak and Kuckzinsky (M-K) method using Barlat and Lian non-quadratic yield criterion. FEM simulation is also performed to calculate the forming limits based on bifurcation theory. Forming limit diagrams (FLDs) and forming limit stress diagrams (FLSDs) determined by analytical and numerical approaches are compared with experimental results of Al3105-St14 two-layer sheet to verify the validity of theoretical models. The formability of two-layer sheet is also compared with the formability of its components. The results show that the forming limit diagram of two-layer sheet is located between the FLDs of separate layers. The effects of the anisotropy and the orientation of layers on formability of two-layer sheet are studied. The higher formability will be achieved in the case of coincidence of rolling directions of layers. تفاصيل المقالة
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  4 - بررسی اثر نانوکورکومین در درمان کبد چرب غیرالکلی در موشهای هایپرکلسترولمی
  سحر فرزانه سپیده فرهی نیا
  با توجه به کاربرد وسیع نانوذرات در پزشکی، بررسی پاتولوژی آنها ضروری بنظر می رسد. ویژگی مهم نانوذرات، اندازه کوچک آنها است. تجمع بیش از حد چربی در کبد و التهاب آن موجب سیروز کبدی می گردد. هدف از این مطالعه، تعیین اثر نانوکورکومین بر بیماری کبد چرب و کلسترول، تری گلیسیرید أکثر

  با توجه به کاربرد وسیع نانوذرات در پزشکی، بررسی پاتولوژی آنها ضروری بنظر می رسد. ویژگی مهم نانوذرات، اندازه کوچک آنها است. تجمع بیش از حد چربی در کبد و التهاب آن موجب سیروز کبدی می گردد. هدف از این مطالعه، تعیین اثر نانوکورکومین بر بیماری کبد چرب و کلسترول، تری گلیسیرید، لیپوپروتئین با دانسیته بالا (HDL)، لیپوپروتئین با دانسیته پایین (LDL)، آسپارتات آمینوترانسفراز (AST) و آلانین آمینوترانسفراز (ALT) سرم می باشد. در این مطالعه 60 سر موش نر در 6 گروه ده تایی تقسیم شدند که شامل: گروه کنترل، گروه کلسترول، گروه کلسترول و کورکومین و سه گروه دریافت کننده دوزهای مختلف نانوکورکومین که به صورت گاواژ تغذیه شدند. میزان پروفایل لیپیدی و آنزیم های کبدی اندازه گیری و نمونه بافت کبد موش ها پس از تثبیت در بافر فرمالین و رنگ آمیزی با هماتوکسیلین و ائوزین مورد مطالعه قرار گرفتند. تحلیل داده ها توسط نرم افزارSPSS انجام شد. بررسی ها نشان داد که درگروه تغذیه شده با دوز بالای نانوکورکومین میزان تری گلیسرید، کلسترول، LDL، ASTو ALT به طور معنی داری کاهش و در دو گروه دریافت کننده دوز 50 و 100 نانوکورکومین، نسبت به گروه کورکومین(غیرنانو) و گروه کلسترول کاهش معنی داری را نشان دادند. پروفایل لیپیدی، AST و ALT گروه کورکومین غیرنانو نسبت به گروه کنترل کاهش معنی داری نداشت اما تغیر در میزانHDL معنی دار بود. تغییرات آسیب شناسی کبد گروه دریافت کننده ی کلسترول موجب ایجاد توده های چربی و گروه های تغذیه شده توسط دوز 50 نانوکورکومین اثری از توده چربی نداشتند. نتایج نشان داد که می توان از دوزهای مناسب نانوکورکومین برای درمان بیماری کبد چرب غیرالکلی استفاده نمود. تفاصيل المقالة
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  5 - Numerical Determination of the Forming Limit Diagram for 304 Stainless Steel Based on Phase Change in Deep Drawing Process
  مسعود نصر اصفهانی مهران مرادی فرهاد حاجی ابوطالبی
  Up to now a large number of models have been developed to measure or predict the damage in equipments. Some of these models have been implemented in ABAQUS software. To implement damage parameters in the software, it is necessary to perform complex and expensive practic أکثر

  Up to now a large number of models have been developed to measure or predict the damage in equipments. Some of these models have been implemented in ABAQUS software. To implement damage parameters in the software, it is necessary to perform complex and expensive practical tests. One of these damage models is Forming Limit Diagram (FLD).The purpose of this research is deriving required parameters for modeling damage by numerical method and using of software. To study and compare of the accuracy of this method, these parameters have been derived with experimental method. FLD parameters for metastable austenitic stainless steel 304 have been extracted from Erichsen test and then phase change from austenite to martensite during deep drawing have been modeled with CLEMEX and SIGMAPLOT software. By defining changes of physical and mechanical properties of elastic-plastic material, the obtained results are transmitted to ABAQUS via developing a VUMAT subroutine in FORTRAN. Then Erichsen test has been simulated in ABAQUS and aforementioned subroutine was used to define changes of properties in simulation. Critical points susceptible for necking in all test cups are determined and numerical FLD was drawn based on principal strains in these points. Finally, the results of this method and practical tests were compared تفاصيل المقالة