Numerical failure analysis of a stretch-bending test on dual-phase steel sheets using a phenomenological fracture model
Numerical failure analysis of a stretch-bending test on dual-phase steel sheets using a phenomenological fracture model
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DOI：
10.1016/j.ijsolstr.2010.07.010
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发表时间：
2010-07
影响因子：
3.6
通讯作者：
M. Luo;T. Wierzbicki
中科院分区：
文献类型：
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作者：
M. Luo;T. Wierzbicki
先进高强度钢（AHSS）由于其优越的强度和显著的重量优势，在汽车工业中得到越来越多的应用。然而，它们的延展性受损引起了许多制造问题。其中之一是在冲压过程中经常观察到的所谓的“剪切断裂”。由于传统的方法，如成形极限图（FLD），无法预测这种类型的裂缝，因此人们努力开发能够预测剪切裂缝的破坏准则。本文采用最新发展的修正Mohr-Coulomb （MMC）韧性断裂准则（Bai and Wierzbicki, 2010）来分析双相（DP）钢板在拉伸弯曲过程中的破坏行为。该薄板的塑性断裂和韧性断裂分别用Hill’48正交异性断裂模型和MMC断裂模型完全表征。为拉伸成形模拟器（SFS）试验建立了三种不同单元类型（3D、壳体和平面应变）的有限元模型（Shih and Shi, 2008），并进行了四种不同R/t值（按板料厚度归一化的模具半径）的数值模拟。结果表明，在所有R/t值下，三维和壳单元模拟均能较准确地预测破坏位置/模式、上模载荷-位移响应以及破裂开始时的壁应力和包角。此外，对三维单元模型进行了一系列参数化研究，研究了张力水平（夹紧距离）、刀具摩擦、网格尺寸和断裂轨迹对破坏模式和载荷-位移响应的影响。
Advanced High Strength Steels (AHSS) are increasingly used in automotive industry due to their superior strength and substantial weight advantage. However, their compromised ductility gives rise to numerous manufacturing issues. One of them is the so-called ‘shear fracture’ often observed on tight radii during stamping processes. Since traditional approaches, such as the Forming Limit Diagram (FLD), are unable to predict this type of fractures, great efforts have been made to develop failure criteria that could predict shear fractures. In this paper, a recently developed Modified Mohr–Coulomb (MMC) ductile fracture criterion (Bai and Wierzbicki, 2010) is adopted to analyze the failure behavior of a Dual Phase (DP) steel sheet during stretch-bending operations. The plasticity and ductile fracture of the present sheet are fully characterized by a Hill’48 orthotropic model and a MMC fracture model, respectively. Finite element models with three different element types (3D, shell and plane strain) were built for a Stretch Forming Simulator (SFS) test (Shih and Shi, 2008), numerical simulations with four different R/t values (die radius normalized by sheet thickness) were performed. It has been shown that the 3D and shell element simulations can predict failure location/mode, the upper die load–displacement responses as well as wall stress and wrap angle at the onset of fracture for all R/t values with good accuracy. Furthermore, a series of parametric studies were conducted on the 3D element model, and the effect of tension level (clamping distance), tooling friction, mesh size and fracture locus on failure modes and load–displacement responses were investigated.