A comparative investigation into the influence of the constitutive model on the prediction of in-plane formability for Nakazima and Marciniak tests

Noder, Jacqueline; Butcher, Cliff

doi:10.1016/j.ijmecsci.2019.105138

Cited by 36 publications

(25 citation statements)

References 142 publications

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“…Figure 15 displays that the pressure correction causes a moderate variation of the data points that do not affect the global tendency given by the linear regressions. The obtained results are in good agreement with those reported in [24,33] in the case of the AA5182-O alloy and an advanced high strength steel. Finally, the correction method adopted in this work to obtain linear deformation paths up to failure is relevant for ultra-thin sheets, since the strain paths obtained in the Nakazima tests exhibited non-linear strain paths.…”

Section: Pressure Effectssupporting

confidence: 89%

“…This could be confirmed by microforming Marciniak tests [35], but these tests are generally performed on a much lower scale than this one (punch of 1.5 mm compared to 35 mm), which is likely to exacerbate other local and scale effects. The corrected FLCs for the pure Cu and CuBe2 alloy in Figure 15 are in good agreement with the results presented by Noder et al [33] for the study of the formability of an AA5182 alloy 1.55 mm thick and DP980, with a sheet thickness of 1.2 mm. These resulting FLCs may be considered as the true forming limits of the selected materials, for perfectly linear strain paths in the absence of normal pressure through the thickness.…”

Section: Pressure Effectssupporting

confidence: 89%

“…According to the procedure described in Min et al [24], a numerical subroutine was developed to correct the FLCs for the tested materials. The new FLC obtained after compensation of the process-dependent effects are analyzed in the light of works already published on thicker steel sheets [24,33].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Development of a Nakazima Test Suitable for Determining the Formability of Ultra-Thin Copper Sheets

Ayachi

Guermazi

Pham

et al. 2020

Metals

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The objective is to propose an accurate method for determining the forming limit curves (FLC) for ultra-thin metal sheets which are complex to obtain with conventional techniques. Nakazima tests are carried out to generate the FLCs of a pure copper and a copper beryllium alloy with a thickness of 0.1 mm. Because of the very small thickness of the sheets, the standard devices and the know-how of this test are no longer valid. Consequently, new tools have been designed in order to limit friction effect. Two different methods are used and compared to estimate the necking: the position-dependent measurement method (ISO Standard 12004-2), and the time-dependent method based on the analysis of the derivatives of the planar strain field. It is shown that the ISO standard method underestimates the forming limit curves. As the results present non linear strain paths, a compensation method is applied to correct the FLCs for the tested materials, which combines the effects of curvature, nonlinear strain paths and pressure. The curvature effect for such thickness and punch diameter on the FLCs is weak. The results show that this procedure enables to obtain FLCs that are close to those determined by the reference Marciniak method, leading to a minimum in major strain that converges to the plane strain state.

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Section: Pressure Effectssupporting

confidence: 89%

Section: Pressure Effectssupporting

confidence: 89%

See 1 more Smart Citation

Development of a Nakazima Test Suitable for Determining the Formability of Ultra-Thin Copper Sheets

Ayachi

Guermazi

Pham

et al. 2020

Metals

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“…Based on the results of photogrammetric measurements, the tool trajectory can be modified to ensure the desired uniform thinning of the sheet along the transverse profile of the ribs. An assessment of possible defects and failures is carried out on the basis of the location of the points corresponding to the actual material deformation in relation to the Forming Limit Curve (FLC) [ 49 , 50 ]. The FLC, as the key feature of the Forming Limit Diagram (FLD), records some pairs of in-plane limit strains (major and minor) and defines the boundary between the safe zone (no necking) and dangerous zone (necking and splitting), which is above the FLC.…”

Section: Resultsmentioning

confidence: 99%

Ultimate Load-Carrying Ability of Rib-Stiffened 2024-T3 and 7075-T6 Aluminium Alloy Panels under Axial Compression

et al. 2021

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Stringer-stiffened panels made of aluminium alloys are often used as structural elements in the aircraft industry. The load-carrying capacity of this type of structure cannot relieve the reduction in strength in the event of local buckling. In this paper, a method of fabrication of rib-stiffened panels made of EN AW-2024-T3 Alclad and EN AW-7075-T6 Alclad has been proposed using single point incremental forming. Panels made of sheets of different thickness and with different values of forming parameters were tested under the axial compression test. A digital image correlation (DIC)-based system was used to find the distribution of strain in the panels. The results of the axial compression tests revealed that the panels had two distinct buckling modes: (i) The panels buckled halfway up the panel height towards the rib, without any appreciable loss of rib stability, and (ii) the rib first lost stability at half its height with associated breakage, and then the panel was deflected in the opposite direction to the position of the rib. Different buckling modes can be associated with the character of transverse and longitudinal springback of panels resulting from local interaction of the rotating tool on the surface of the formed ribs.

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“…They calibrated their model experimentally and investigated the localized deformation. 31 Studies on the effect of texture have been fully developed by previous researchers, [32][33][34][35] but, at the best knowledge of the authors, the influence of grain geometry, their aspect ratio, and heterogeneity on FLD and stress-strain relation has not been investigated until now. In this article, considering the mentioned parameters on the tension behavior, the FLD of aluminum 2024 has been obtained by the finite element method using the crystal-plasticity model.…”

Section: Introductionmentioning

confidence: 99%

An innovation in finite element simulation via crystal plasticity assessment of grain morphology effect on sheet metal formability

Habibi

Darabi

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part L:

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Experimental and numerical study regarding the uniaxial tensile test and the forming limit diagram are addressed in this paper for AL2024 with the face-centered cube structure. First, representation of a grain structure can be obtained directly by mapping metallographic observations via scanning electron microscopy approach. Artificial grain microstructures produced by Voronoi Tessellation method are employed in the model using VGRAIN software. By resorting to the finite element software (ABAQUS) capabilities, the constitutive equations of the crystal plasticity were utilized and implemented as a user subroutine material UMAT code. The hardening parameters were calibrated by a trial and error approach in order to fit experimental tensile results with the simulation. Then the effect of the changing grain size, the heterogeneity factor, and the grain aspect ratio were studied for a uniaxial tensile test to emphasize the importance of the microstudy behavior of grains in material behavior. Furthermore, the polycrystal plasticity grain distribution was employed in the Nakazima test in order to obtain the forming limit diagram. The crystal plasticity-driven forming limit diagram reveals more accurate strains, taking into account the involving the micromechanical features of the grains. An innovative approach is pursued in this study to discover the necking angle, both in tensile test or Nakazima samples, showing a good agreement with the experiment results.

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A comparative investigation into the influence of the constitutive model on the prediction of in-plane formability for Nakazima and Marciniak tests

Cited by 36 publications

References 142 publications

Development of a Nakazima Test Suitable for Determining the Formability of Ultra-Thin Copper Sheets

Development of a Nakazima Test Suitable for Determining the Formability of Ultra-Thin Copper Sheets

Ultimate Load-Carrying Ability of Rib-Stiffened 2024-T3 and 7075-T6 Aluminium Alloy Panels under Axial Compression

An innovation in finite element simulation via crystal plasticity assessment of grain morphology effect on sheet metal formability

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