Inverse determination of the flow curve in large range of strains for cylindrical tensile specimen

Abstract

In this study, an inverse method with the integration of finite element simulation and optimization algorithms is proposed to determine the flow curve of cylindrical specimen characterized by the modified Voce hardening model. The tensile test is repetitiously simulated with different combinations of model parameters designed through Latin hypercube design method, where the baseline values and variation ranges of model parameters are identified through Leroy–Bridgman method, obtaining different simulated load–displacement curves. The corresponding response is defined as the sum of the absolute area difference between the simulated load–displacement curves and the experimental one. The relationship between the model parameters and the response is established through response surface methodology and the optimal parameters combination in the modified Voce model is then determined through nonlinear programming by quadratic Lagrangian. In the case of uniaxial tensile test of mild steel Q345, the inversely identified flow curve is validated by numerically reproducing the experimental load–displacement curve and necking profile. The results indicate that the proposed inverse method is capable of evaluating the flow curve in large range of strains for cylindrical specimen accurately.

A Review of Flow Characterization of Metallic Materials in the Cold Forming Temperature Range and Its Major Issues

“…These are true of the flow models at the elevated temperature. For example, models by Fields-Bachofen [70], Zhang [72], Chen et al [77], Lin and Chen [78], Johnson-Cook [79], Khan-Huang-Liang [80,81], Ludwigson [82], Zerilli and Armstrong [83], Voyiadjis-Almasri [84], Bodner-Partom [85], Nadai and Manjoine [86], and Joun et al [16] can be considered to be extended Ludwik models. On the other hand, models by Hartley-Srinivasan [87], Kim-Tuan [88], Rusinek-Klepaczko [89] and Ghosh [30], and models by Voce-Kocks [91], Double-Voce [18], Hockett-Sherby [92], modified Hockett-Sherby [93], El-Magd et al [94], Voce generalized [95], Bergstorm [96] and Voyiadjis-Abed [97] are classified as extended Swift (represented by Ludwik model) and Voce models, respectively.…”

Methods for measuring friction-independent flow stress curve to large strains using hyperbolic shaped compression specimen

“…Such kind of method utilizes FE analysis to minimize the discrepancy between experimental and simulated response by iteratively updating the flow stresses or the parameters of selected hardening model. 7 Shin et al 8 proposed an inverse method for the identification of compressive flow stress curve and friction coefficient by minimizing the differences between the simulated and experimental load-displacement curves and between the bulge shapes of the FE model and the experimental specimen. Zhuang et al 9 adopted an inverse method to determine the flow curve of medium-thick metal plate by using cylindrical compression specimen.…”