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Gillo Giuliano

Bio: Gillo Giuliano is an academic researcher from University of Cassino. The author has contributed to research in topics: Superplasticity & Forming processes. The author has an hindex of 14, co-authored 55 publications receiving 557 citations.


Papers
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TL;DR: In this article, a method to determine the material constants of superplastic alloys from a free forming test at constant pressure is described, and the finite element simulation of the free forming process is used to examine the validity of the suggested method.

58 citations

Journal ArticleDOI
TL;DR: In this article, a finite element method (FEM) was used to characterize superplastic materials with the help of free-forming tests in which the stress state induced is biaxial (nearer the real stress conditions to which the material is subject during the forming process).
Abstract: Superplastic forming (SPF) of sheets is a very interesting and useful process when there is a need to produce items with complex geometry and integrated structures characterized by high specific resistance. To accurately model SPF processes it is important to know the constitutive equation of the material. With the help of the finite element method (FEM) this study proposes an innovative method for determining the characteristic parameters of superplastic materials. This method requires the material to undergo free-forming tests in which the stress state induced is biaxial (nearer the real stress conditions to which the material is subject during the SPF processes that are of interest to industry). The dimensions of the sheet and the forming die do not place any constraint on the application of this type of characterization procedure. The method adopted to characterize superplastic materials was validated by means of experimental activity carried out on an AZ31 magnesium-based alloy.

39 citations

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TL;DR: In this paper, constant pressure free bulging for superplastic materials is analyzed by finite element method and expressions to determine the constants of the super-plastic material have been proposed.
Abstract: In recent years, there has been a considerable interest in the application of superplastic forming in the aircraft and automotive industries to realize complex parts. This requires a detailed design of the technological process in order to better exploit its peculiar potentialities. Nowadays, the finite element method represents the mainly used technique to plan the sheet metal forming processes whose simulation requires determination of material constants for superplastic materials. The aim of the present work is aimed to show a simple method to characterize superplastic materials. In this study, constant pressure free bulging for superplastic materials is analysed by finite element method and expressions to determine the constants of the superplastic materials have been proposed. In order to support the proposed method, numerical and experimental activities have been carried out which show the good reliability of values obtained from proposed expressions.

37 citations

Journal ArticleDOI
TL;DR: In this article, the variable pressure-time load profile during a superplastic forming process was predicted to get best performances, in terms of ductility, on the material, and the so obtained curve has been used in experimental free bulging tests on an AZ31 magnesium alloy sheet.
Abstract: In this work, an original algorithm, proposed in [1–2], has been used to predict the variable pressure-time load profile during a superplastic forming process, in order to get best performances, in terms of ductility, on the material. The so obtained curve has been used in experimental free bulging tests on an AZ31 magnesium alloy sheet. Tests results, in particular the maximum bulge height achieved by the material, have been compared with numerical results and with constant-pressure experimental tests.

31 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the development history and applications of Al-Li alloys over the last few years are reviewed, and the main issue of anisotropic behavior of all the alloys is discussed.

360 citations

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TL;DR: In this paper, a generalised forming limit diagram (GFLD) is proposed to allow visual representation of the resulting forming limit strains, which can be used to expand process operating windows.

181 citations

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TL;DR: In this paper, a comprehensive review of widely used forming processes for aluminium alloys, under cold, warm and hot forming conditions, and the material characteristics and equipment used for each process are presented.

177 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of tool rotation on an incremental forming process is investigated in terms of forming forces, temperatures reached and surface roughness, whereas neither the heating of the sheet caused by the friction nor the surface finishing feel the effects of this parameter significantly.

152 citations

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TL;DR: In this paper, the authors focus on the current state and recent developments in different stages of product design: springback prediction, springback compensation and optimization by finite element (FE) analysis.
Abstract: Numerical simulations are being deployed widely for product design. However, the accuracy of the numerical tools is not yet always sufficiently accurate and reliable. This article focuses on the current state and recent developments in different stages of product design: springback prediction, springback compensation and optimization by finite element (FE) analysis. To improve the springback prediction by FE analysis, guidelines regarding the mesh discretization are provided and a new through-thickness integration scheme for shell elements is launched. In the next stage of virtual product design the product is compensated for springback. Currently, deformations due to springback are manually compensated in the industry. Here, a procedure to automatically compensate the tool geometry, including the CAD description, is presented and it is successfully applied to an industrial automotive part. The last stage in virtual product design comprises optimization. This article presents an optimization scheme which is capable of designing optimal and robust metal forming processes efficiently.

135 citations