Theoretical study of void closure in nonlinear plastic materials

Zhang, Xiaoxun; Cui, Zhenshan

doi:10.1007/s10483-009-0509-7

Cited by 22 publications

(18 citation statements)

References 36 publications

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“…Tiny voids can hardly be considered by such a macroscopic approach, since their volume is very small and becomes negligible with respect to the volume of the workpiece. As pointed out in 2009 by Zhang and Cui [13] and Zhang et al [44], there is at present a lack of applicable and accurate criterion in evaluating void closure. Based on micromechanical results from the literature, the authors proposed two numerical models for void closure.…”

Section: Criteria For Void Closurementioning

confidence: 99%

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Void closure criteria for hot metal forming: A review

Saby

Bouchard

Bernacki

2015

Journal of Manufacturing Processes

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International audienceVoid elimination through mechanical closure remains of prime importance for industrial applications. This paper presents a critical review on a large number of studies dealing with void closure in hot metal forming processes. In the literature, two main approaches were identified at two different scales: a macroscopic approach at the process scale and a micro-analytical approach at the void scale. Using the macroscopic approach, entire processes are generally considered with workpieces containing one or several voids, dealing with hot forging, hot rolling and related processes. Qualitative results, as well as empirical criteria and empirical prediction models are presented and discussed in this paper. Using the micro-analytical approach, an isolated void in an infinite matrix is considered and its evolution is analytically predicted. Analytical and semi-analytical prediction models involve a certain number of assumptions that are discussed in an industrial context. This paper presents a comparison between seven prediction models, in terms of void volume evolution under conditions that are typical for industrial applications. Stress triaxiality ratios are over the range [−1.2, 0] and several material behaviours are considered. It is shown that empirical models. Empirical models are hardly generalizable, as they are based on particular case studies involving one given void state or one given process. On the other hand, analytical and semi-analytical models suffer from strong assumptions. Consequently, their use in an industrial context remains limited. The use of a meso-scale approach is shown as a potentially powerful approach, as it may take advantage of both existing approaches from literature

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Section: Criteria For Void Closurementioning

confidence: 99%

“…where parameters c 1 and c 2 are tabulated functions of m [13]. The volumetric strain-rate is plotted in Fig.…”

Section: Analytical Solutionsmentioning

confidence: 99%

Void closure criteria for hot metal forming: A review

Saby

Bouchard

Bernacki

2015

Journal of Manufacturing Processes

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“…Based on the analytical evolution of a sphere found by Duva and Hutchinson [4] and the analytical evolution of a crack-like shape found by He and Hutchinson [6], Zhang and Cui [22] proposed a model for predicting the volume evolution of an initially spherical void, by analytically taking into account the change of shape during deformation. A semi-empirical model was also proposed by the same authors [23], by adding correction terms to the solutions obtained by Duva and Hutchinson [4], in order to empirically take into account the change of shape during deformation.…”

Section: Introductionmentioning

confidence: 99%

A geometry-dependent model for void closure in hot metal forming

Saby

Bouchard

Bernacki

2015

Finite Elements in Analysis and Design

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International audienceDuring production of large metal workpieces, an internal presence of voids is usually observed. Such internal defects are generally closed up using hot metal forming processes, such as hot forging or hot rolling. Prediction models for void closure, associated with process simulation, are extremely powerful tools and might significantly support process design. However, there is at present a lack of accurate models being able to predict void closure according to industrial conditions, particularly in terms of void geometries. In this paper, an original model for void closure is presented, accounting for the void׳s geometry and orientation, as well as the mechanical state during deformation. The model is build and calibrated based on a wide campaign of finite element simulations at the scale of a representative volume element. Various void geometries are defined and several mechanical states are prescribed on a range that is representative of industrial loadings. The model׳s accuracy is verified using industrial data and was compared to several models from literature. Great advantages are obtained for non-spherical voids in terms of void volume evolution

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“…They found that a critical amount of effective strain was needed to close the voids. Zhang and Cui (2009a) developed an analytical model for the closing of a spherical void during axial compression of a cylinder. They verified their model using two-dimensional FEM.…”

Section: Introductionmentioning

confidence: 99%