Prediction of Forming Limit Diagrams for Materials with HCP Structure

• Type: Article in International Scientific Journal
• Date: 2015

Authors

Wu, SH (Author) Other; Song, NN (Author) Other; F.M. Andrade Pires (Author) FEUP; Santos, AD (Author) Other

Journal

Title: Acta Metallurgica Sinica (English Letters)

Vol. 28

Pages: 1442-1451

ISSN: 1006-7191

Publisher: Science Press

Indexing

ISI Web of Knowledge - 0 Citations

Other information

Authenticus ID: P-00K-4QG

DOI: 10.1007/s40195-015-0344-3

Abstract (EN): The forming limit diagram (FLD) is an important tool to be used when characterizing the formability of metallic sheets used in metal forming processes. Experimental measurement and determination of the FLD is time-consuming and therefore the analytical prediction based on theory of plasticity and instability criteria allows a direct and efficient methodology to obtain critical values at different loading paths, thus carrying significant practical importance. However, the accuracy of the plastic instability prediction is strongly dependent on the choice of the material constitutive model [1-3]. Particularly for materials with hexagonal close packed (HCP) crystallographic structure, they have a very limited number of active slip systems at room temperature and demonstrate a strong asymmetry between yielding in tension and compression [4, 5]. Not only the magnitude of the yield locus changes, but also the shape of the yield surface is evolving during the plastic deformation [4]. Conventional phenomenological constitutive models of plasticity fail to capture this unconventional mechanical behavior [4, 6]. Cazacu and Plunkett [6] have proposed generic yield criteria, by using the transformed principal stress, to account for the initial plastic anisotropy and strength differential (SD) effect simultaneously. In this contribution, a generic FLD MATLAB script was developed based on Marciniak-Kuczynski analytical theory and applied to predict the localized necking. The influence of asymmetrical effect on the FLD was evaluated. Several yield functions such as von Mises, Hill, Barlat89, and Cazacu06 were incorporated into analysis. The paper also presents and discusses the influence of different hardening laws on the formability of materials with HCP crystal structures. The findings indicate that the plastic instability theory coupled with Cazacu model can adequately predict the onset of localized necking for HCP materials under different strain paths.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10