基于内变量的7075铝合金热变形统一粘塑性损伤本构模型

Unified viscoplastic damage constitutive model of 7075 aluminum alloy during hot deformation based on internal state variable

针对难以掌握高强铝合金热变形中的损伤演化规律、精确预测成形性等问题,开展高强铝合金热变形过程统一粘塑性损伤本构模型研究。基于内变量法,考虑孔洞的形核与长大、瞬时塑性变形功率和塑性应变对损伤演变率的影响,建立3种统一粘塑性损伤本构模型。通过遗传算法优化计算得到模型参数,进行计算值与试验值相关性分析。结果表明,采用考虑孔洞的形核与长大影响的粘塑性损伤本构模型能更好地描述7075铝合金的热变形行为,在相同温度下,7075铝合金的损伤积累速率随应变速率的增加呈下降趋势;在相同应变速率下,7075铝合金的损伤积累则逐渐增加,断裂应变逐渐下降。

Aiming at the problems that it is difficult to master the damage evolution of high-strength aluminum alloy and to predict formability accurately,the unified viscoplastic damage constitutive models for high-strength aluminum alloy during hot deformation were studied.Based on internal variable method,considering the influence of nucleation and growth of voids,instantaneous plastic deformation power and plastic strain on the damage evolution rate,three kind of unified viscoplastic damage constitutive models were established.Model parameters were optimized by genetic alorithm,the correlation between the calculated values and the test values was analyzed.The results show that the viscoplastic damage constitutive models considering the influence of nucleation and growth of voids can describe the hot deformation behavior of 7075 aluminum alloys better,the damage accumulation rate of 7075 aluminum alloy decreases with the increase of strain rate at the same temperature,and the damage accumulation increases gradually with the increase of temperature at the same strain rate,and the fracture strain decreases gradually.