Strengthening mechanisms, deformation behavior, and anisotropic mechanical properties of Al-Li alloys: A review

Generalised forming limit diagrams showing increased forming limits with non-planar stress states

A review on forming techniques for manufacturing lightweight complex—shaped aluminium panel components

The influence of tool rotation on an incremental forming process

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.

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Numerical product design: Springback prediction, compensation and optimization

Superplastic forming of advanced metallic materials

Constitutive equation for superplastic Ti–6Al–4V alloy

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.

The determination of material parameters from superplastic free-bulging tests at constant pressure

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.

On the Evaluation of Superplastic Characteristics using the Finite Element Method

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.

Gillo Giuliano

Papers

Superplastic forming of advanced metallic materials

Constitutive equation for superplastic Ti–6Al–4V alloy

The determination of material parameters from superplastic free-bulging tests at constant pressure

On the Evaluation of Superplastic Characteristics using the Finite Element Method

On the optimisation of superplastic free forming test of an AZ31 magnesium alloy sheet