A generalized Hosford yield function for weakly-textured sheets of cubic metals
A generalized Hosford yield function for weakly-textured sheets of cubic metals
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立方金属弱织构板材的广义 Hosford 屈服函数
DOI：
10.1016/j.ijplas.2012.09.007
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发表时间：
2013-02-01
影响因子：
9.8
通讯作者：
Man, Chi-Sing
中科院分区：
文献类型：
--
作者：
Huang, Mojia;Man, Chi-Sing
我们考虑轧制的立方金属薄板，它宏观上是由微小的微晶组成的正交体，微观上是聚集体。微晶的择优取向产生了晶体织构，这是造成板材塑性各向异性的主要原因。用取向分布函数或等效的织构系数来表征晶体织构。对于立方金属薄板的弱织构，我们提出了一种新的推广的Hosford屈服准则，该准则适用于任何应力状态，并且作为区分特征，明确地包含了晶体织构对塑性各向异性的影响。除了主应力外，我们的新屈服函数还取决于主应力方向、某些织构系数(可通过X射线衍射或电子背散射衍射测量)和三个材料参数，即各向同性多晶的指数Eta、单轴屈服应力Y-iso和描述晶体织构影响强度的参数β。我们推导了通过单轴和/或平衡双轴拉伸试验来校准这三个材料参数的公式。作为例子，根据(I)泰勒模型在单轴和平衡双轴拉伸试验中的预测和(Ii)关于两种铝合金的Q值和单轴屈服应力的方向相关性的实验数据来校准这三个材料参数。用泰勒模型校正得到的面心立方和体心立方薄板的指数ETA分别约为10和6.6，与Hosford及其同事早期的研究结果符合得很好。对于所研究的两种铝合金，新的屈服准则可以很好地描述Q值的塑性各向异性和单轴屈服应力的塑性各向异性。(C)2012爱思唯尔有限公司。保留所有权利。
We consider rolled sheets of cubic metals which are macroscopically orthorhombic and microscopically aggregates of tiny crystallites. The preferred orientations of the crystallites create crystallographic texture, which is a main cause for the plastic anisotropy of the sheet metal. Crystallographic texture is characterized by the orientation distribution function or, equivalently, the texture coefficients. In this paper we propose, for weakly textured sheets of cubic metals, a new generalization of the Hosford yield criterion, which is applicable for any state of stress and, as a distinguishing feature, incorporates explicitly the effects of crystallographic texture on plastic anisotropy. Besides the principal stresses, our new yield function depends on the principal stress directions, certain texture coefficients (which can be measured by X-ray diffraction or electron backscatter diffraction), and three material parameters, namely the exponent eta, the uniaxial yield stress Y-iso for the isotropic polycrystal, and a parameter beta which describes the strength of the effects of crystallographic texture. We derive formulas with which the three material parameters can be calibrated by uniaxial and/or balanced biaxial tension tests. As examples, the three material parameters are calibrated against (i) the predictions of the Taylor model in uniaxial and balanced biaxial tension tests and (ii) experimental data on directional dependence of the q-value and uniaxial yield stress that pertain to two aluminum alloys. The values of the exponent eta determined by calibration with the Taylor model are approximately 10 and 6.6 for FCC and BCC sheet metals, respectively, which square well with the earlier findings of Hosford and coworkers. For the two aluminum alloys studied, it is found that both the plastic anisotropy of the q-value and of the uniaxial yield stress can be described reasonably well by the new yield criterion. (C) 2012 Elsevier Ltd. All rights reserved.