An Integrated Methodology for HER Determination in Hole Expansion Test

Cruz, Daniel J.; Santos, Abel D.; Amaral, Rui; Mendes, Joaquim; Miranda, Sara S.; Fernandes, J.V.

doi:10.1007/978-3-030-68277-4_16

Cited by 1 publication

(4 citation statements)

References 18 publications

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“…The instrumented device presented in [25] was used to acquire the real-time evolution of the hole expansion throughout the test. The image acquisition system presented in Figure 1 comprises a digital web camera (Microsoft LifeCam Studio Win USB 1080p) with a maximum image resolution of 2560 × 2048 pixels and a maximum frame rate of 30 fps, and an illumination device installed at the center of the top of the system.…”

Section: Methodsmentioning

confidence: 99%

“…The parameters considered for the edge detection step and Hough Transform are summarized in Table 2. The final inner diameter, 2r, is converted from pixels to millimeters using a conversion factor that takes into account multiple factors, including the resolution of the acquisition image system, as discussed in Section 2; the thickness of the material; and the displacement of the punch at the time the image was acquired [25]. The methodology described can be applied to sheet materials with thicknesses ranging from 0.5 to 3 mm, and can measure hole diameters with a maximum accuracy of ±0.1 mm.…”

Section: Hole Diameter Measurement Algorithmmentioning

confidence: 99%

“…Cruz et al [25] developed an instrumented device to acquire the real-time evolution of the hole dimensions during the test. They also developed a DIP tool, based on the Circular Hough Transform (CHT), to automatically detect and measure the different hole diameters, enabling a more accurate determination of the final hole expansion ratio.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 2.Resolution of the used image acquisition system calibrated for different measurement plane displacements, ∆d m.plane (adapted from[25]). …”

mentioning

confidence: 99%

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Application of Digital Image Processing Techniques to Detect Through-Thickness Crack in Hole Expansion Test

Cruz

Amaral

Santos

et al. 2023

Metals

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Advanced high-strength steels (AHSS) have become increasingly popular in the automotive industry due to their high yield and ultimate tensile strengths, enabling the production of lighter car body structures while meeting safety standards. However, they have some setbacks compared to conventional steels, such as edge cracking through sheet thickness caused by forming components with shear-cut edges. When characterizing the formability of sheet metal materials, the hole expansion test is an industry-standard method used to evaluate the stretch-flangeability of their edges. However, accurately visualizing the first cracking is usually tricky and may be subjective, often leading to inconsistent results and low reproducibility with some impact of the operator on both direct and post-processing measurements. To address these issues, a novel digital image processing method is presented to reduce operator reliance and enhance the accuracy and efficiency of the hole expansion test results. By leveraging advanced image processing algorithms, the proposed approach detects the appearance of the first edge cracks, enabling a more precise determination of the hole expansion ratio (HER). Furthermore, it provides valuable insights into the evolution of the hole diameter, allowing for a comprehensive understanding of the material behavior during the test. The proposed method was evaluated for different materials, and the corresponding HER values were compared with the traditional method.

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Section: Methodsmentioning

confidence: 99%

Section: Hole Diameter Measurement Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Figure 2.Resolution of the used image acquisition system calibrated for different measurement plane displacements, ∆d m.plane (adapted from[25]). …”

mentioning

confidence: 99%

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