“Faster process optimization is achieved using the specific attributes of materials, resulting in shorter trouble shooting time during the trial forming stage, which has a significant economic impact.”

This paper proposes a relatively simple and accurate theory for representing metal behavior beyond the elastic limit. It also describes a new experiment and gives a methodology to identify the material coefficients. We think that this work is highly cited because, beside its great theoretical and experimental merits, it can be readily applied in industry, which relies on accurate numerical simulations to optimize manufacturing processes and product performance.

This work describes a new analytical approach for the mathematical representation of plastic anisotropy in sheet metals, which synthesizes many years of research in this active field.

Plasticity is the ability of a material—for instance, a flat sheet—to deform to and retain a given shape—for instance, a car fender. The shape results from the distribution of plastic strains (deformation) imposed by forming loads throughout the part. This distribution depends on many factors including plastic anisotropy, the ability of a material to exhibit different properties when tested in different directions.

The strain distribution determines the success of a forming operation or its failure, primarily by localization of the deformation which leads to fracture. In order to account for the contribution of the material behavior in numerical simulations of sheet forming processes, the description of plastic anisotropy is of prime importance.

In this work, a specific continuum potential, which accounts for the crystal structure of a metal and the average aspects of its microstructure, is proposed to capture the anisotropic behavior. Thus, the numerical simulations, which are performed for process optimization prior to manufacturing set-up, are conducted numerically in a time-efficient manner and with a realistic material response.

Faster process optimization is achieved using the specific attributes of materials, resulting in shorter trouble-shooting time during the trial forming stage, which has a significant economic impact.

It became apparent in the late 1980s that all manufacturing processes in the future would be first simulated before industrial implementation. Sheet metal forming was one of the most important applications where this technology could be applied. One of the issues was to represent the plastic behavior of sheet materials.

Since we work for a material company (aluminum), we felt that we were in the best position to conduct this type of research at an academic level and to provide accurate descriptions of the plastic behavior of our materials to our customers. In an established industry, the main obstacle is to convince enough R&D and business unit decision makers that this technology has value and to get enough support for pursuing this long term effort.

An optimum use of materials can lead to important weight reduction in automotive and aerospace structures which, in turn, can translate into significant waste reduction and energy savings. This research work contributes to these general goals.