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In This paper dynamic forming limit diagram has been investigated as fracture criteria for St13 steel. In fact, effect of various strain rates has been studied. This fracture criterion is based on the Marciniak-Kuczynski (M-K) theory and Solutions of equations have been obtained by applying the Newton -Raphson method. After solution three forming limit diagrams has been created: independent strain rate, dependent strain rate and dynamic forming limit diagram. Dynamic damage criteria investigates forming limit diagram in every strain rate. It is observed that the forming limit is increased by increasing the strain rate, Also for considering the anisotropic and the elastic-plastic behavior of material, the Hill 1948 yield criterion and the Swift hardening rule are used respectively. Also this paper is concerned with the uniaxial tensile properties and formability of sheet metal in relation to the strain rate effects. In order to verification of the results several experiments have been done with a Drop Hammer which is a high speed impact machine. For comparison between quasi static and dynamic damage criterions, all of the stages of experiment were simulated in finite element software Abaqus and results are compared together.

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Nowadays the forming limit curves is very useful in forming of metal sheets and the effect of yield criteria is one of the most important parameters in prediction of the limit strain especially in anisotropic aluminum sheets. In this paper, first the effects of advanced BBC2008, Soare2008, Plunkett2008 and Yld2011 yield criteria on limit strain calculation and then on forming limit stress diagram will be investigated. Plastic instability model is studied based on Marciniak-Kuczynski model and the non-linear equations are solved by using Newton-Rophson method. These functions are used to evaluate the limit forming predictability of AA2090-T3 aluminum sheet based on the Swift hardening law and is compared with the forming limit curves predicted by Hill’s 1948 classic yield criterion. It was observed that the classic yield functions is not appropriate for anisotropic aluminum sheets forming estimation. Numerical results obtained from the forming limit diagram for AA5754 with Plunkett2008 yield function and Swift hardening law, although the experimental results confirm at close range to plane strain case, but CPB06ex2 yield criterion to predict the behavior of anisotropic aluminum sheets. The limit strain prediction for AA3104-H19 by using Yld2011 yield criterion and Voce hardening law show better conformity with experimental results.

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Single point incremental forming is a new and flexible method for 3D parts production of sheet metal. In this way, a hemispherical tool forms incrementally the sheet being clamped in perimeter. Because of the nature of localized deformation in this process, the formability is higher and forming forces are lower as compared to traditional sheet metal forming process. However, in this method dimensional accuracy is somewhat low due to spring back and bending occurred in boundaries. Recently, the incremental forming process using frictional heat has been developed. In this research, the experimental effect of generated heat by friction stir of the tool on dimensional accuracy in components of AA3105 sheet has been studied at high rotational speeds. By this method, due to friction movements of tool, the temperature of formation area rises while fixing the general temperature of sheet by spraying cooling liquid. Then, the sheet has low strength in contact region with tool while it has high strength in other areas. As a result, the force imposed on the sheet as well as the undesirable plastic deformation will decrease. Also, by decreasing the yielding stress, elastic strain and spring back decreases as well. An increase in formability because of softening of forming area is another contribution of this strategy. This idea has been studied by production of some parts of truncated-pyramid geometry and changing rotational speed from 1000 to 7000 RPM. The results show that at speed higher than 3000 RPM, formability and dimensional accuracy of the parts increase.

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Manufacturing structures with light weight and high strength in the industry is growing. Therefore, use of bent profiles and tubes in structures is increasing. In this paper, method of the incremental tube forming for bending tube is investigated. In this method using combination of spining and bending tube simultaneously improves the bending process for high-strength metals. The analytical model for incremental tube forming process is provided. The model is used for understanding the physics of the process and determine the amount of the required bending moment. In addition, numerical modeling of the incremental tube forming process for to forecast failures caused by bending is performed. The numerical modeling has been used to evaluate the effective parameters on the incremental tube forming process, such as feeding the second step, the rotational speed of spinning tool, feeding tube axis in the whole process and the effect of attack angle the spinning rolls and the results show The numerical model can be used to examine defects related to the speed of the process and Before producing the appropriate parameters to produce higher quality final product selected.

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In the new sheet metal forming process as incremental sheet forming and spinning forming, this is not perfectly true in Marciniak-Kuczyinski model to assume that sheet deformation occurs in the plane-stress state indispose there are normal compressive stress and through-thickness stress. In this type of forming processes, the obtained limit strains refer to improving the sheet forming. However, in researches the effects of through-thickness shear stresses, also known as out-of-plane shear, has been studied less. The generalized forming limit diagram is a great curve that includes all six components of the stress tensor. In this paper, the effect of normal comprehensive and through-thickness shear stresses on the limit strain AA6011 aluminum sheet using a modified M-K and the anisotropic Yield function, Hill 48 and by using numerical solutions of nonlinear equations, Newton-Raphson method. The first the forming limit diagram was drawn with the assumption that the through-thickness shear stresses and then the effects of normal comprehensive stress and through-thickness shear stress on the limit strains were proved and the generalized forming limit curves were obtained. The results show that forming limits can be increased significantly by both normal compressive stress and through-thickness shear stresses. Also, the effects of normal stress on increasing the formability of sheet compared with the effects of through-thickness shear stress is greater.

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Nowadays, studies have been developing in order to use antimicrobial properties of plants instead of using synthetic preservatives. Jujube is one of the famous herbs.  Jujube (Ziziphus jujube. Mill) belongs to family of Ramnaseh and native to the central areas of the Iran plateau. The fruit, leaves and root of this plant have medicinal and wellness properties. In this study, evaluated some physico-chemical of jujube extract (Extraction yield, Moisture, water activity, Fat content, Ash, Brix) and its effect on the mold of Aspergillus flavus. Extraction of dried and Ground jujube fruit was done by soaking with Hydroethanol solvent. Chemical composition of the extract was determined by GC-MS method. So the evaluated minimum inhibitory concentration (MIC) and the minimum fungal concentration (MFC) of extract against Aspergillus fulvous (PTCC 5004) by the dilution method in a liquid medium. In the next step, different concentrations of the extract were sprayed on corn grains and after placing a disk containing suspension of Mold spores in each petri dish. Growth of mold on corn grains was measured during 7 days. The results showed that the hydroethanolic extract of jujube fruit has an anti-mold effect against Aspergillus fulvous and the minimum inhibitory concentration of extract in the culture medium was determined 350 μg / ml and there was not observed any lethality at concentrations less than 1000 μg / ml. The minimum inhibitory concentration of the extract in the blanched corn grain medium was 5000 μg / ml. Therefore, the hydroethanolic extract of jujube fruit has an inhibitory effect on Aspergillus flavus but does not have the inactivation effect on this mold and its spores.

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In this study, the effect of adding different concentrations of Bene kernel (5 and 10%) and its microliposomes (400 ppm) on the physicochemical and sensory properties of cream was investigated. The treatments of this research were as follow: T1 (cream with 30% fat), T2 (cream with 20% fat and microliposome), T3 (cream with 20% fat+ microliposome and 5% Bene kernel oil), T4 (cream with 20% fat+ microliposome and 10% Bene kernel oil). PH and syneresis during storage and the parameters of viscosity, texture, color index and sensory evaluation were measured. Results showed that in all samples, during the storage, syneresis increased and the amount of pH decreased (P <0.05). By adding Bene kernel oil, the viscosity of the samples increased (P <0.05). The addition of 10% Bene kernel oil reduced the brightness and increase softness of the texture, and it was not approved in terms of sensory evaluation. T3 was chosen as optimal treatment. The results of this study showed that encapsulating Bene kernel oil as source of phenolic and tocopherol compounds and also applying its oil, help us using beneficial properties of Bene and also provides a positive step towards the production of low-fat cream and promoting consumer health.