Calculation of forming limit diagrams using Hill's 1993 yield criterion

Rezaee-Bazzaz, A.; Noori, Hadi; Mahmudi, R.

doi:10.1016/j.ijmecsci.2011.01.007

Cited by 22 publications

(10 citation statements)

References 29 publications

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“…2 The FLD provides the limiting strains that a sheet metal can sustain School of Mechanical Engineering, Iran University of Science and Technology, Iran while being formed. Laboratory testing has shown that the forming limit diagrams are influenced by several factors including strain hardening exponent and anisotropy coefficients, [3][4][5] strain rate, [6][7][8][9][10][11][12][13] temperature, 8,[13][14][15][16] grain size and microstructure, [17][18][19][20][21] sheet thickness, [22][23][24] strain path changes [25][26][27][28] and heat treatment. [29][30][31] In recent years many experimental techniques have been developed to investigate the FLD from different aspects.…”

Section: Introductionmentioning

confidence: 99%

A comparative study on determination of forming limit diagrams for industrial aluminium sheet alloys considering combined effect of strain path, anisotropy and yield locus

Janbakhsh

Djavanroodi

Riahi

2012

The Journal of Strain Analysis for Engineering Design

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Suitability of AA2024-T3 and AA5083-H111 aluminium sheet alloys for forming operations in room temperature were examined by using forming limit diagrams with different strain paths. In the experimental part, circular bulge, nongrooved tensile as well as grooved tensile specimens were used. This was done to simulate the following: (a) biaxial stretching region (positive range of minor strain), (b) uni-axial strain path and (c) strain path from uni-axial tension to plane strain region of the forming limit diagram, respectively. The effects of combined strain paths coupled with material anisotropy were taken into account in each stage. Tensile properties as well as formability parameters were correlated in accordance with the attained forming limit diagrams. Average plastic strain ratio and planar anisotropy, in addition to work hardening exponents of the samples, were calculated from the test data and the effects on the forming limit diagrams were discussed. Moreover, comparisons were made between experimental and theoretical forming limit diagrams. It is shown that experimental forming limit diagrams are in very good agreement with the theoretical predictions, particularly when BBC2000 yield criteria are used for the M-K model. In addition, theoretical prediction by using the Hill93-Swift model showed small deviation with the experimental forming limit diagrams. Finally, finite element simulations were carried out to investigate the numerical forming limit diagrams through an industrial sheet metal forming simulation software. It was consequently shown that, due to frictional effects resulting from hemispherical-shaped punch, the finite element results depicted small deviation compared to the experimental data.

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Section: Introductionmentioning

confidence: 99%

A comparative study on determination of forming limit diagrams for industrial aluminium sheet alloys considering combined effect of strain path, anisotropy and yield locus

Janbakhsh

Djavanroodi

Riahi

2012

The Journal of Strain Analysis for Engineering Design

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“…Assuming that the sheet where the biaxial tensile stress is applied has an initial defect at a narrow region across the plate width in a direction perpendicular to the major principal stress direction as shown in Figure 10, the initial imperfection of the plate is expressed as Equation (5). Generally, for FLD based on M-K model, 0 f is at least 0.98 [5,[25][26][27][28][29]. Therefore, in this paper, 0 f was assumed to be 0.995.…”

Section: M-k Modelmentioning

confidence: 99%

“…where t A0 is the initial thickness of the uniform region A and t B0 is the initial thickness of the imperfection region B. f 0 can be assumed or obtained by the surface roughness experiment. Generally, for FLD based on M-K model, f 0 is at least 0.98 [5,[25][26][27][28][29]. Therefore, in this paper, f 0 was assumed to be 0.995.…”

Section: M-k Modelmentioning

confidence: 99%

Acquisition and Evaluation of Theoretical Forming Limit Diagram of Al 6061-T6 in Electrohydraulic Forming Process

Woo

Song

Kang

et al. 2019

Metals

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The current study examines the forming limit diagram (FLD) of Al 6061-T6 during the electrohydraulic forming process based on the Marciniak–Kuczynski theory (M-K theory). To describe the work-hardening properties of the material, Hollomon’s equation—that includes strain and strain rate hardening parameters—was used. A quasi-static tensile test was performed to obtain the strain-hardening factor and the split-Hopkinson pressure bar (SHPB) test was carried out to acquire the strain rate hardening parameter. To evaluate the reliability of the stress–strain curves obtained from the SHPB test, a numerical model was performed using the LS–DYNA program. Hosford’s yield function was also employed to predict the theoretical FLD. The obtained FLD showed that the material could have improved formability at a high strain rate index condition compared with the quasi-static condition, which means that the high-speed forming process can enhance the formability of sheet metals. Finally, the FLD was compared with the experimental results from electrohydraulic forming (EHF) free-bulging test, which showed that the theoretical FLD was in good agreement with the actual forming limit in the EHF process.

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“…Forming limit diagram provides the limiting strains a sheet metal can sustain whilst being formed. Laboratory testing has shown that the forming limit diagrams are influenced by several factors including strain hardening exponent and anisotropy coefficients [18][19][20], strain rate [21][22][23], temperature [24], grain size and microstructure [25][26], sheet thickness [27], strain path changes [28][29], and heat treatment [30].…”

Section: Forming Limit Diagrams (Fld)mentioning

confidence: 99%