Formability evaluation for low conductive sheet metal by novel specimen design in electromagnetic forming

Li, Fenqiang; Mo, Jinhan; Li, Jianjun; Zhao, Jun

doi:10.1007/s00170-016-8893-9

Cited by 22 publications

(14 citation statements)

References 12 publications

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“…This range of strain rates lies within the loading conditions attained in dynamic forming processes (e.g. see Dariani et al (2009), Golovashchenko et al (2013) and Li et al (2017), among others). Moreover, the numerical results reported by N'souglo et al (2020) and Zheng et al (2020) indicated that the effect of inertia on neck retardation starts to be important for L−1 in the range 0.06 − 0.1.…”

Section: The Effect Of Porositysupporting

confidence: 55%

A new analytical model to predict the formation of necking instabilities in porous plates subjected to dynamic biaxial loading

2021

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Section: The Effect Of Porositysupporting

confidence: 55%

A new analytical model to predict the formation of necking instabilities in porous plates subjected to dynamic biaxial loading

2021

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“…However, in many instances, failures occur at regions other than the apex, which lead to a non-constant strain path. This can be observed in the results of Li et al [10], where failure is seen at the die entry radius. In electrohydraulic forming, Rohatgi et al [11] observed fracture at the ligament in cruciform-shaped specimens.…”

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confidence: 58%

Novel Approach and Interpretation for the Determination of Electromagnetic Forming Limits

Demir¹,

Goyal

Hahn

et al. 2020

Materials

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A new method to determine electromagnetic forming limits curves (EM-FLCs) for sheet metals is proposed. The different strain paths (between uniaxial and biaxial tension) are achieved by specific tool coil and specimen designs. It is ensured that the apex of the specimen deforms on a constant strain path, and excess bending at the apex is avoided. This is done so that the determined EM-FLCs are comparable to their quasi-static counterparts. The method determines the EM-FLCs for the aluminum alloys AA-1050a-H24 and EN AW-5083-H111 and the magnesium alloy Mg AZ31-O. Overall, it is observed that the necking limits in electromagnetic forming (EMF) are higher compared to quasi-static forming. The fracture surfaces of electromagnetically deformed specimens are examined to reveal the existence of out-of-plane shear stresses. A numerical analysis corroborates this observation and their variation with strain rate. The presence of such stresses is proposed as a possible reason for the increased necking limits in EMF. As reasons for higher forming limits, previous research has identified inertial stabilization, strain rate hardening, die impact, and change in deformation mechanism. The current study reaffirms the positive effect of inertial stabilization and makes key observations in the increase of twinning in EMF of Mg AZ31-O.

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“…The calculations presented in this section are performed for two different imposed initial major strain rates 361ε 0 xx = 500 s −1 and 10000 s −1 , for which the value of the inertia parameter isL −1 ≈ 0.005 and ≈ 0.1, respectively. et al ( 2009), Golovashchenko et al (2013) and Li et al (2017), among others). Moreover, the numerical results reported by N'souglo et al (2020) and Zheng et al (2020) indicated that the effect of inertia on neck retardation starts to be important forL −1 in the range 0.06 − 0.1.…”

Section: The Effect Of Porosity 360mentioning

confidence: 93%

A new analytical model to predict the formation of necking instabilities in porous plates subjected to dynamic biaxial loading

Kumar¹,

N'souglo²,

Rodríguez-Martínez³

2021

Preprint

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In this paper, we have developed a linear stability analysis to predict the formation of necking instabilities in porous ductile plates subjected to dynamic biaxial stretching. The mechanical behavior of the material is described with the Gurson-Tvergaard-Needleman constitutive relation for progressively cavitating solids (Gurson, 1977; Tvergaard, 1981, 1982; Tvergaard and Needleman, 1984) which considers the voids to be spherical and the matrix material isotropic with yielding defined by the von Mises (1928) criterion. The analytical model is formulated in a two-dimensional framework in which the multiaxial stress state that develops inside the necked region is approximated with the Bridgman (1952) correction factor, superimposing a hydrostatic stress state to the uniform stress field that develops in the plate before localization. As opposed to the linear stability models published so far to model dynamic necking in ductile plates, which consider the material to be fully dense and incompressible, the approach developed in this paper provides new insights into the interplay between porosity and inertia on plastic localization. In addition, the predictions of the theoretical model for the critical strain leading to necking formation have been compared with unit-cell finite element calculations performed in ABAQUS/Explicit (2019). Satisfactory quantitative and qualitative agreement has been found between the theoretical and computational approach for loading paths ranging from plane strain tension to nearly equibiaxial tension, loading rates varying from 100 s−1 to 10000 s−1, and different values of the initial void volume fraction ranging from 0.01 to 0.1. Both analytical and finite element results suggest that the influence of porosity on necking localization increases, due to early voids coalescence, as the loading rate increases and the loading path approaches equibiaxial tension. The original formulation developed in this paper serves as a basis for analytically modeling the dynamic formability of porous ductile plates, and it can be readily extended to consider more complex porous plasticity theories, e.g. constitutive models which consider the anisotropy of the material (Benzerga and Besson, 2001) and/or voids with different shapes (Gologanu et al., 1993; Monchiet et al., 2008).

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Formability evaluation for low conductive sheet metal by novel specimen design in electromagnetic forming

Cited by 22 publications

References 12 publications

A new analytical model to predict the formation of necking instabilities in porous plates subjected to dynamic biaxial loading

A new analytical model to predict the formation of necking instabilities in porous plates subjected to dynamic biaxial loading

Novel Approach and Interpretation for the Determination of Electromagnetic Forming Limits

A new analytical model to predict the formation of necking instabilities in porous plates subjected to dynamic biaxial loading

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