An Experimental Methodology to Characterize the Uniaxial Fracture Strain of Sheet Metals Using the Conical Hole Expansion Test

Narayanan, A.; Abedini, Armin; Khameneh, F.; Butcher, Cliff

doi:10.1007/s11665-022-07460-6

Cited by 3 publications

(2 citation statements)

References 33 publications

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“…Novel test methods have been developed to suppress necking instabilities and obtain proportional loading until fracture. Examples include the conical hole expansion and hole tension tests for uniaxial tension [6][7][8], the VDA238-100 v-bend and dihedral punch tests for plane strain tension [9,10], and miniature biaxial punch tests [11,12]. Fracture characterization in simple shear has been challenging due to its high fracture strains and propensity for premature edge cracking in tension [13].…”

Section: Introductionmentioning

confidence: 99%

“…Finite element analysis (FEA) was employed to validate the stress state within the coupons. Subsequently, the numerical results obtained from the FEA were compared to the experimental data acquired through digital image correlation (DIC) strain measurement [8,[33][34][35][36]. The proportional fracture locus of the DP1180 steel was then calibrated and lengthscale effects of the finite-elements model and DIC discussed.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Numerical Fracture Characterization of DP1180 Steel in Combined Simple Shear and Uniaxial Tension

Khameneh

Abedini

Butcher

2023

Metals

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Current tests for plane stress characterization of fracture in automotive sheet metals include simple shear, uniaxial, plane strain, and biaxial tension, but there is a significant gap between shear and uniaxial tension. Presently, it remains uncertain whether the fracture strain experiences a reduction between simple shear and uniaxial tension or undergoes an exponential increase as the triaxiality decreases. Fracture in combined simple shear and tension is complicated by premature edge cracking in tension along with a strong sensitivity of fracture strain to the measurement lengthscale. To address these issues, several existing simple shear geometries were modified and evaluated, with a focus on obtaining approximately linear strain paths corresponding to combined uniaxial tension and simple shear suitable for experimental fracture characterization using digital image correlation (DIC). An experimental and numerical investigation was conducted using two planar geometries that do not require through-thickness machining and can be easily tested on a universal test frame. Finite-element analysis was used to investigate the influence of the notch eccentricity on the stress state and predicted fracture location. The most promising geometry in each coupon type was then selected and tested for a dual-phase advanced high-strength steel, DP1180. The performance of the two planar geometries was evaluated based on the linearity of strain and stress state, along with the location of fracture initiation. The best geometry was then used to evaluate and recalibrate the modified Mohr-Coulomb (MMC) fracture locus with data in combined shear and tension. The initial MMC calibration using four fracture tests that suppressed necking provided an accurate estimate for the fracture strain in combined uniaxial tension and simple shear. The MMC model correctly predicted a valley in the fracture strain between these two loading conditions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Fracture Characterization of DP1180 Steel in Combined Simple Shear and Uniaxial Tension

Khameneh

Abedini

Butcher

2023

Metals

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On the Characterization of Fracture in Uniaxial Tension: Experiments and Modeling of DP1180 Steel Sheet

Khameneh,

Abedini,

Narayanan

et al. 2023

J. of Materi Eng and Perform

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Sheared Edge Formability Characterization of High Strength Aluminum Alloys at Room and Elevated Temperatures using Hole Expansion Tests

Narayanan

George

Cheong

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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High strength 6000- and 7000-series aluminum alloys have significant potential for automotive light weighting due to their high strength-to-weight ratios. Alternate thermal processing routes and warm forming operations with rapid heating to 150 - 300°C are being explored to expand their forming process windows. While the constitutive and formability behavior of these alloys at elevated temperatures is an active area of research, limited data is available on their sheared edge stretchability, particularly under elevated temperature forming conditions. To this end, the influence of cutting clearance on the edge fracture limits of two precipitation hardening alloys, AA6013-T4 and AA7075-T6, and a non-heat treatable AA5182-O were first investigated at room temperature using the conical hole expansion test. A 12% clearance was found to be suitable for the three materials and used to process the hole expansion samples prior to warm forming. Microhardness tests were used to characterize the depth and severity of the shear affected zone (SAZ) for the AA7075-T6 before and after the warm forming cycle. The forming temperature was found to increase the hole expansion ratio by approximately 400%, 150%, and 520% for the AA5182-O, AA6013-T4, and AA7075-T6 respectively relative to the room temperature tests. The edge stretchability during W-temper forming of the AA6013 and AA7075 at room temperature was also assessed. It was observed that W-temper forming negatively influenced the hole expansion of AA6013 by approximately 30% relative to the T4 condition. Conversely, the hole expansion ratio for AA7075 when formed in W-temper increased by over 35% with respect to the T6 temper.

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An Experimental Methodology to Characterize the Uniaxial Fracture Strain of Sheet Metals Using the Conical Hole Expansion Test

Cited by 3 publications

References 33 publications

Experimental and Numerical Fracture Characterization of DP1180 Steel in Combined Simple Shear and Uniaxial Tension

Experimental and Numerical Fracture Characterization of DP1180 Steel in Combined Simple Shear and Uniaxial Tension

On the Characterization of Fracture in Uniaxial Tension: Experiments and Modeling of DP1180 Steel Sheet

Sheared Edge Formability Characterization of High Strength Aluminum Alloys at Room and Elevated Temperatures using Hole Expansion Tests

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