金属材料循环应变硬化/软化瞬态响应的数学模型

本文讨论了金属材料循环硬化/软化瞬态响应特性,定量分析了在应力—应变响应中应力幅值(在对称应变控制下)的变化规律,给出了应力幅值变化的数学表达式。该式表明,应力幅值的变化不仅与材料性质和材料进入塑性变形范围的次数有关,而且还与应变幅值的大小有关。与已有的数学模型相比较,本文提出的模型与试验结果符合较好,并且无需拟合诸如循化硬化/软化系数这样的试验参数,因而可以节省大量的费用。此外,使用本文的模型由计算给出了瞬态过程中循环强度系数和应变硬化指数的变化规律,发现二者在寿命前半部分循环中变化很大,而在寿命后半部分循环中变化很小,这与试验得到的结果是一致的。

Mathematical Model for Modeling Cyclic Hardening/Softening Transient Response of Metallic Materials

Cyclic hardening/softening transient reponse of metallic materials is discussed in this paper. The variation of stress amplitude in stress-strain response (by strain control) is quantitatively analyzed.The mathematical formula for modeling the variation of stress amplitude is given. The formula demonstrates that the variation of stress amplitude deals with not only the material characteristics and the reversal number of material deformation into the plastic range, but also the strain amplitude. Comparing with experimental results, the model presented in this paper is better than the other mathematical models. Moreover the model has no need of any experimental parameters such as the cyclic hardening/softening coefficient which comes from a lot of experimental data, so plenty of payout can be saved. The variations of cyclic strength coefficient and cyclic hardening exponent during transient response are also calculated and analyzed in this paper. It is found that both variations are great in the first half of their lifes, but little in the second half, which is in accordance with the experimental results.