Identification of the post-necking hardening response of rate- and temperature-dependent metals

INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES

卷:115

Article

Korkolis, Yannis P.¹ 

[1] Univ New Hampshire, Dept Mech Engn, 33 Acad Way, Durham, NH 03824 USA

关键词: Work-hardening;    Necking;    Rate-dependence;    Temperature-dependence;    Stainless steel;    Optimization;    Response surface methodology;   

DOI  :  10.1016/j.ijsolstr.2017.03.012

来源: Elsevier

【 摘 要 】

A method for identifying the material hardening curves past the limit of necking in uniaxial tension and across a range of strain-rates and temperatures in a fully-coupled way is proposed. Experiments on microtubes of 304 L stainless steel, which is a rate- and temperature-dependent material, were performed using a custom isothermal testing setup. Digital Image Correlation and Infrared Thermography provided full-field measurements of the strain and temperature during testing. The identification procedure uses a finite element (FE) model of the experiments and the problem is cast as one of mathematical optimization. The corresponding objective function has input parameters that control the post-necking shape of the hardening curves and a scalar output that represents the proximity between the FE predictions of the force-average axial strain response and the experimental data. Since the objective function in not available in closed form and is expensive to evaluate, an efficient optimization procedure that requires a limited number of function evaluations is proposed. The method proposed here is then applied to identifying the post-necking hardening response under different assumptions, starting from a single material curve with no rate and temperature effects included, to a family of curves with both rate and temperature considered in a coupled way. To validate the family of hardening curves identified for 304 L stainless steel, a fully-coupled FE model is used to simulate a conventional tension test. This model is shown to be able to reproduce this experiment, including the strain and temperature fields which develop during testing. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

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