Advanced Modelling of Sheet Metal Forming Considering Anisotropy and Young’s Modulus Evolution

The uncertainties of modern, adaptable sheet metal forming systems are classified into model errors and disturbances. To improve the control of production, disturbances in the forming process need to be reduced. For this purpose, a new data flow system was introduced. It connected the data flow of all influencing material parameters into the “material property control function”. To control on-line the forming production line and acquire necessary material data, an indentation test was implemented. The main parameters to follow in this test are pile-up or sink-in values after the embossing of the ball-shaped tool into the material where the innovative approach of fully anisotropic material description was used. To set-up an optimal indentation test, parametric studies were performed with material data of AW 5754-H22. Finite element simulations were used to evaluate the influences of indenter diameter, contact friction and forming history of used the material. Fully anisotropic material behaviour was considered. Novel to this approach were a) the linking of the linear correlation of pile-up with the indentation depth described by gradient k, and b) the linking of gradient k with different pre-strains by a new power function.

show abstract

“…In the numerical program ABAQUS, a material's anisotropy can be described with Hill's yield criterion [17] and [20], as expressed in Eq. (2).…”

Section: • the Most Important Contribution To The Research Of Indentamentioning

confidence: 99%

“…Decreasing the numerical model of the indentation test to one quarter only [20] requires double-sided axis-symmetry ( Fig. 4), which was used to shorten the computer calculation times.…”

Section: Model Mesh and Loadsmentioning

confidence: 99%

Study of Influential Parameters of the Sphere Indentation Used for the Control Function of Material Properties in Forming Operations

Satošek

Valeš

Pepelnjak

2019

SV-JME

View full text Add to dashboard Cite

show abstract

“…Nevertheless, it is not quite enough to understand the mechanical behavior of each layer individually given that the global behavior is also driven by the interaction between layers. Moreover, when very thin skins are considered, such as the ones on the micro-sandwich materials, the mechanical properties can change and new constitutive model parameters are needed to accurately describe the formability and springback phenomena, as claimed by Starman et al (2014). Luzin et al (2005) compare several experimental techniques to measure the Young Modulus of samples made from sub-millimeter thickness layers, and observed that the elastic properties can no longer be measured with conventional mechanical tests.…”

Section: Introductionmentioning

confidence: 99%

Hybrix: Experimental characterization of a micro-sandwich sheet

Pimentel

Alves

Merendeiro³

et al. 2016

Journal of Materials Processing Technology

View full text Add to dashboard Cite

The development of new micro-sandwich sheets (i.e. two metallic skins separated by a composite core), which can be shaped by conventional sheet metal forming processes, became one of the most interesting materials and promising automotive applications in the past few years. However, due to the lack of understanding of certain fundamentals related with the mechanical behavior of micro-sandwich sheets during forming processes, the transfer and scale-up of this promising material to industry has been hindered. To overcome problems concerning the formability of these new materials and make the conventional sheet forming process more adapted, the experimental characterization of the micro-sandwich sheets is absolutely necessary. In this work, a new approach to experimentally characterize micro-sandwich sheets, with the mechanical properties of the core unknown, is presented. Firstly, for the characterization of stress-strain curves and anisotropy, uniaxial tensile tests in 3 different orientations with respect to rolling direction are performed on total micro-sandwich specimens and skin-only specimens. Secondly, the mechanical properties of the core are then deduced from micro-sandwich and skins' mechanical properties, and the constitutive parameters established. Additionally, 5 different Nakazima geometries were punched according to ISO 12004 for formability assessment. Experimental Forming Limit Curves (FLC), punch forces and principal strain data were recorded during the tests using high resolution cameras and system GOM ARAMIS. Finally, the experimental mechanical tests were numerically reproduced. The systematic excellent agreement between numerical and experimental results is a good validation of the methodology proposed in the present work to identify the constitutive properties of the micro-sandwich materials.

show abstract

“…Among the mechanisms, roughly grouped into micromechanical models (e.g. [3] to [6]), uncoupled models (e.g. [1] and [2]) and coupled phenomenological models (e. g. [1], [7] and [8]), the Lemaitre coupled phenomenological model, following the continuum damage mechanics (CDM) may be considered as most appropriate for direct and continuous material characterization.…”

Section: Introductionmentioning

confidence: 99%

Identification of Out-of-Plane Material Characteristics through Sheet-Metal Blanking

Bolka

Slavič

Boltežar

2015

SV-JME

View full text Add to dashboard Cite

The mechanical characteristics of sheet metals are typically identified in the in-plane direction, although the sheet-metal forming processes (e.g., blanking, deep-drawing) are normally applied in the out-of-plane direction. As the mechanical characteristics are not necessarily constant, their direct experimental evaluation through the forming process would enable material monitoring and process optimization, and, additionally, material characterization in the out-of-plane direction. Full, partial (to a certain depth) and sequential (consecutive partial steps to full penetration) blanking experiments are performed on a laboratory blanking apparatus to correlate the out-of-plane material characteristics with the in-plane ones. The well-established in-plane approach to damage is introduced for the out-of-plane direction to determine the isotropic Lemaitre damage variable. Furthermore, yield and ultimate shear stresses are determined and correlated to their respective in-plane counterparts, offering a new insight in the sheet-metal blanking process. Keywords: cutting and forming, constitutive behavior, elastic-plastic material, mechanical testing, ductile damage, out-of-plane experiment Highlights • Experimental out-of-plane sheet-metal material characterization. • Use of in-plane approach for out-of-plane characterization. • Direct material characterization and correlation to in-plane parameters. • Experimental Lemaitre damage characterization in the out-of-plane direction. • Full, partial and sequential blanking experiments on laboratory blanking apparatus.

show abstract

Advanced Modelling of Sheet Metal Forming Considering Anisotropy and Young’s Modulus Evolution

Cited by 13 publications

References 20 publications

Study of Influential Parameters of the Sphere Indentation Used for the Control Function of Material Properties in Forming Operations

Study of Influential Parameters of the Sphere Indentation Used for the Control Function of Material Properties in Forming Operations

Hybrix: Experimental characterization of a micro-sandwich sheet

Identification of Out-of-Plane Material Characteristics through Sheet-Metal Blanking

Contact Info

Product

Resources

About