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

Thin sheets of aluminum alloys are widely used for the packaging of pharmaceutical and cosmetic products and in the food industry; however they present critical issues during the forming process. The blow forming process, which is widely used in the glass and plastics industries and for the hot forming of metal sheets, allows solving the problems related to the lubrication and the small tolerance ranges of the tools required by the well-known deep drawing process to form a thin sheet. In this work, the blow forming process is proposed for the first time to cold form thin metal sheets. Its advantage is connected with the use of equipment with a simple shape and, therefore, less expensive. Specifically, this work evaluates the time needed to form a simplified part; this is a critical aspect to apply this forming process to the food packaging industry. Moreover, this process represents the first step to developing a method-ology for evaluating the constitutive equation of thin sheets as an alternative to tensile test that has some critical issues connected with specimens&#8217; manufacturing and test carrying out. 

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Cold Blow Forming of a Thin Sheet in AA8006 Aluminum Alloy

In this study experimental bulging tests carried out on the superplastic AZ31 magnesium‐based alloy are investigated to determine the influence of the forming pressure on the final thickness at the dome apex. A statistical analysis concurs to establish i) a mathematical relation of the thickness as the height measured at the dome apex varies and ii) that the influence of forming pressure on the thickness trend versus dome apex height is not negligible.

Pressure influence on the final thickness at the dome apex in superplastic bulging tests for magnesium‐based az31 alloy

Using a finite element calculation code, this work analyses the influence of friction during a stamping test conducted on the AA6060 aluminium-based alloy. The study focuses on phenomena happening when the sheet necking appears. This condition, based on the Hill’s localized necking theory and the Swift’s diffuse necking theory, is dependent on the material hardening index. This work shows that the punch stroke at the necking condition point is maximum when the main strain measured on the sheet surface are unbalanced and close to a balanced biaxial tension condition.

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Friction influence on the AA6060 aluminium alloy formability

Modellazione dei processi di formatura superplastica

This work presents a finite element model to analyze the distribution of the strains due to an axisymmetric stretching of a metal sheet. The sheet is characterized by a variable initial thickness. The resulting strain state is compared with that of a sheet with a constant initial thickness. The results of the present study allow asserting that the distribution of strains in the sheet can be controlled by setting opportunely the trend of the sheet initial thickness. In this way, it is possible to see that, starting from a sheet with variable initial thickness, a lighter final product is obtained, whose final thickness distribution is more uniform than that of the product obtained from a classic stretching process that requires a sheet with constant initial thickness. Encouraging results from an experimental activity carried out on an AA6060 aluminum alloy sheet, whose trend of initial thicknesses was prepared by removing material from a commercial sheet with a constant thickness, allow us to note the good agreement with what was theoretically highlighted.

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Gillo Giuliano

Papers

Cold Blow Forming of a Thin Sheet in AA8006 Aluminum Alloy

Pressure influence on the final thickness at the dome apex in superplastic bulging tests for magnesium‐based az31 alloy

Friction influence on the AA6060 aluminium alloy formability

Modellazione dei processi di formatura superplastica

Strain State in Metal Sheet Axisymmetric Stretching with Variable Initial Thickness: Numerical and Experimental Results