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 5 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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Uncertainty quantification for conical hole expansion test of DP800 sheet metal

Pham,

Barlo,

Islam

et al. 2024

Int J Mater Form

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The hole expansion ratio (HER) observed in a standardized hole expansion test (HET) is commonly used to determine the edge fracture of steel sheets. A large variation of the measured HER restricts the practical application of the method. This study presents a systematic investigation on uncertainties in the HER of DP800 sheet material, including the hole-edge quality, pre-strain due to the hole-punching process, the friction coefficient, and the determination of fracture. An artificial neural network was trained to develop a surrogate model using a database gained from a thousand finite element simulations of the HET. Monte-Carlo simulations were performed using the trained surrogate model to characterize the distribution of the HER. Sensitivity analysis via Sobol’s indices is calculated to determine the influence of the input variables on the output. It is found that the pre-strain and pre-damage generated during the hole punching process in the shear-affected zone dominate the variation of the HER. Discussions on reducing the output’s variation are detailed. In general, these findings provide valuable insights for the determination of HER as well as the edge crack behavior of the investigated DP800 steel sheet.

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

Cited by 5 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

Uncertainty quantification for conical hole expansion test of DP800 sheet metal

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