An improved damage evolution model to predict fracture of steel sheet at elevated temperature
An improved damage evolution model to predict fracture of steel sheet at elevated temperature
复制标题
预测钢板高温断裂的改进损伤演化模型
DOI：
10.1016/j.jmatprotec.2015.08.007
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发表时间：
2016-02-01
影响因子：
6.3
通讯作者：
Bariani, P. F.
中科院分区：
文献类型：
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作者：
Tang, B. T.;Bruschi, S.;Bariani, P. F.
高强度钢（HSS）在高温下的板材成型工艺越来越多地应用于生产白车身零件，而这些零件以前是在室温下生产的。正确选择与温度相关的参数是数值模拟过程设计中最关键的方面之一。特别是，通常在专用 FEM 代码中实现的成形极限图 (FLD) 对材料成形性的描述在应用于热冲压工艺时显得受到很大限制，因为材料行为取决于温度和应变率。在本文中，对基于连续损伤力学（CDM）的损伤模型进行了修改，以考虑高温的影响，从而能够全面描述热冲压过程中相互作用的耦合热-机械-微观结构事件。然后将修改后的损伤模型应用到热冲压过程的数值模型中，以描述 22MnB5 板材的断裂起始。在 550 摄氏度至 850 摄氏度的高温下，以不同的应变率进行拉伸测试，以确定校准所提出的损伤模型所需的材料参数。在高温下进行了中岛型实验并进行了数值模拟，以验证所提出的方法。裂纹扩展起始临界载荷和断裂位置方面的数值结果与实验结果的比较表明，该模型能够预测热冲压过程中的延性断裂起始。 (C) 2015 Elsevier B.V. 保留所有权利。
Sheet forming processes of High Strength Steel (HSS) at elevated temperature are being increasingly applied to produce parts of the car body-in-white, which were previously produced at room temperature. The proper selection of the temperature-related parameters is one of the most critical aspects in the process design with the numerical simulation. In particular, the description of the material formability by Forming Limit Diagrams (FLDs), which are usually implemented in dedicated FEM codes, appears strongly limited when applied to the hot stamping process, as the material behavior is dependent on both the temperature and strain rate. In this paper, a damage model based on the Continuum Damage Mechanics (CDM) was modified to account for the elevated temperature influence, enabling a comprehensive description of the coupled thermo-mechanical-microstructural events that interact during the hot stamping process. The modified damage model was then implemented in the numerical model of the hot stamping process to describe the fracture onset of 22MnB5 sheets. Tensile tests were carried out at elevated temperatures, in a range between 550 degrees C and 850 degrees C, at different strain rates, to identify the material parameters necessary for the calibration of the proposed damage model. Nakajima-type experiments at elevated temperature were conducted and numerically simulated to validate the proposed approach. The comparison between numerical and experimental results in terms of critical load at crack growth initiation and fracture location shows that the proposed model is able to predict the ductile fracture onset in hot stamping process. (C) 2015 Elsevier B.V. All rights reserved.