研究論文
6000系アルミニウム合金板の穴広げ限界の予測手法
キーワード:
6000 series aluminum alloy,
hole expansion limit,
forming limit strain,
fracture limit strain,
strain gradient
2022 年 72 巻 12 号 p. 702-707
詳細
2022 年 72 巻 12 号 p. 702-707
This study investigates the applicability of the forming limit strain (FLS) and fracture limit strain (FrLS) determined from uniaxial tensile tests for predicting the hole expansion limit of a 6000-series aluminum alloy sheet. Since the stress state at the hole edge in hole expansion is uniaxial, the FLSs and FrLSs of the test sample are determined from the uniaxial tensile tests at various cut angles from the rolling direction. The experimental methods for determining the FLS and FrLS are presented. In the hole expansion experiment, the development of the strain distribution at a position 3 mm apart from the hole edge was precisely measured using digital image correlation method for three different hole diameters, and the maximum principal strain along the hole edge, ε1, was compared with the FLS and FrLS. We have confirmed that the fracture in the hole expansion experiment always occurred at the hole edge and when ε1 reached the FrLS, regardless of the hole diameter. Therefore, the FrLS can be a criterion for predicting the hole expansion limit of the test sample.
