运用应变梯度塑性理论模拟颗粒增强铝合金强度及延伸率的尺寸效应

Simulation of size effect on strength and elongation of Al alloy wity rarticles reinforcement using strain gradient plasticity concept

运用基于细观机制的应变梯度塑性理论模拟了不同晶粒尺度、不同第二相颗粒直径及体积分数的铝合金应力应变曲线。结果表明,在相同条件下,随着第二相颗粒直径的减小,或随着第二相体积分数的增加,合金的强度明显增强。相反,随着第二相颗粒体积分数的增加,或随着第二相颗粒直径的减小,合金的均匀延伸率均有所下低。同时对不同晶粒尺寸的铝合金应力应变相应的分析表明,第二相颗粒分布的不均匀性对其力学性能也有一定的影响。

By using the micro-mechanism-based strain gradient plasticity theory, the stress-strain relationships of Al alloys with different grain size,and different particles diameter and volume fraction were simulated. The results indicated that：at the same condition, the strength of alloy evidently increases with the decrease of particle diameter or with increase of particle volume fraction. In the opposite, the uniform elongation of alloys slightly decreases with the increase of particle volume fraction or with decrease of particle diameter. At the same time,it indicated that the uneven distribution of particle can affect the mechanics capability of alloys by analyzing the stress-strain relationships of Al alloys with different grain sizes.