The finite element simulation of high-temperature magnesium AZ31 sheet forming

Abstract

How would you……describe the overall signifi cance of this paper? Finite-element simulations, with a new material constitutive model, are used to predict hot gas-pressure forming of AZ31 magnesium sheet into both simple and complex part geometries. These simulations are shown, through comparisons with formed parts, to provide useful predictions of the forming process. Furthermore, the current limitations of simulation capabilities are also described. …describe this work to a materials science and engineering professional with no experience in your technical specialty? A new material constitutive model is formulated for fi ne-grained AZ31 magnesium sheet material. This model is based upon the deformation mechanisms currently understood to operate at the temperatures, strain rates and stress states which occur in commercial hot blow-forming operations. Commercial fi nite-element-method codes are used with this material model to predict sheet forming in balanced-biaxial and plane-strain stress states, as well as the complex stress states of a commercial trunk closure component. All simulations are compared against formed parts to validate the FE predictions using the new material model. …describe this work to a layperson? Computerized simulations are used to predict the high-temperature forming of magnesium sheet material into complex vehicle components. Finite element (FE) simulations will be vitally important to advancing magnesium alloy sheet forming technologies for vehicle component manufacturing. Although magnesium alloy sheet has been successfully formed into complex components at high temperatures, material constitutive model development for FE simulations has not kept pace with the needs of forming process design. This article describes the application of a new material constitutive model in FE simulations for hot forming of magnesium AZ31 alloy sheet. Simulations of forming both simple geometries from laboratory studies and complex parts from production trials are presented and compared with experimental results.

New approach to gas pressure profile prediction for high temperature AA5083 sheet forming

“…2 (Verma et al, 2009), the pressure was first linearly ramped to 1.38 MPa (200 psi) in 2 min (689 kPa/min or 100 psi/min), and then held constant until contact was established at all locations of the die (i.e. the end of forming).…”

Numerical study of the solution heat treatment, forming, and in-die quenching (HFQ) process on AA5754

“…In recent years, efforts have been made to develop FE models capable of simulating sheet metal forming processes at elevated temperatures accurately, using material models comprised of phenomenological or physically based equations calibrated using the results of uniaxial tension tests [12][13][14][15]. Tabular flow stress data can also be used to describe the material if a sufficient range of values is input, to prevent excessive extrapolation of the data and potentially inaccurate results [16].…”

“…Tabular flow stress data can also be used to describe the material if a sufficient range of values is input, to prevent excessive extrapolation of the data and potentially inaccurate results [16]. A failure criterion is necessary to model the material behaviour upon the nucleation of damage and beyond the point of necking, to accurately simulate the later stages of the forming process [15,17]. For non-isothermal processes, coupled thermo-mechanical simulations are conducted using temperature dependent material models, to account for the heat transfer between the blank and the tool parts [18].…”

Developing a Zener–Hollomon Based Forming Limit Surface for Warm Sheet Forming of Magnesium Alloy

“…The Coulomb friction coefficient at the interfaces between the tooling components and the sheet material was assumed as 0.1 at 25-150 • C, 0.2 at 200 and 250 • C, and 0.4 at 300 • C. The selection of relatively high values of friction coefficients at higher temperatures is based on friction study on magnesium alloys at different lubrication conditions at elevated temperatures [32][33][34][35]. Local increase of friction coefficient at high temperatures is due to the possible failure of lubricant and friction coefficient selection strategy discussed in [36].…”