考慮微觀結(jié)構(gòu)特征長度演化的內(nèi)變量黏塑性本構(gòu)模型
發(fā)布時間：2018-10-29 09:48
【摘要】：在金屬晶體材料高應(yīng)變率大應(yīng)變變形過程中,存在強(qiáng)烈的位錯胞尺寸等微觀結(jié)構(gòu)特征長度細(xì)化現(xiàn)象,勢必對材料加工硬化、宏觀塑性流動應(yīng)力產(chǎn)生重要影響。基于宏觀塑性流動應(yīng)力與位錯胞尺寸成反比關(guān)系,提出了一種新型的BCJ本構(gòu)模型。利用位錯胞尺寸參數(shù),修正了BCJ模型的流動法則、內(nèi)變量演化方程,引入了考慮應(yīng)變率和溫度相關(guān)性的位錯胞尺寸演化方程,建立了綜合考慮微觀結(jié)構(gòu)特征長度演化、位錯累積與湮滅的內(nèi)變量黏塑性本構(gòu)模型。應(yīng)用本文模型,對OFHC銅應(yīng)變率在10-4~103 s-1、溫度在298~542K、應(yīng)變在0~1的實驗應(yīng)力-應(yīng)變數(shù)據(jù)進(jìn)行了預(yù)測。結(jié)果表明:在較寬應(yīng)變率、溫度和應(yīng)變范圍內(nèi),本文模型的預(yù)測數(shù)據(jù)與實驗吻合很好;與BCJ模型相比,對不同加載條件下實驗數(shù)據(jù)的預(yù)測精度均有較大程度的提高,最大平均相對誤差從9.939%減小為5.525%。
[Abstract]:In the process of high strain rate and large strain deformation of metallic crystal materials, there is a strong phenomenon of microstructural length refinement, such as dislocation cell size, which is bound to have an important effect on material work hardening and macroscopic plastic flow stress. Based on the inverse relationship between the stress of macroscopic plastic flow and the size of dislocation cell, a new BCJ constitutive model is proposed. Based on the parameters of dislocation cell size, the flow rule of BCJ model and the evolution equation of internal variables are modified. The evolution equation of dislocation cell size considering the correlation of strain rate and temperature is introduced, and the evolution of characteristic length of microstructures is established. Visco-plastic constitutive model of internal variables for dislocation accumulation and annihilation. Using this model, the experimental stress-strain data of OFHC copper at 10-4 103s-1, temperature 298N 542K and strain 0U 1 have been predicted. The results show that the predicted data of this model are in good agreement with the experiment in a wide range of strain rate, temperature and strain. Compared with the BCJ model, the prediction accuracy of the experimental data under different loading conditions is greatly improved, and the maximum average relative error is reduced from 9.939% to 5.525%.
【作者單位】： 昆明理工大學(xué)機(jī)電工程學(xué)院;
【基金】：國家自然科學(xué)基金項目(11462008)
【分類號】：O344.4
，
本文編號：2297353
[Abstract]:In the process of high strain rate and large strain deformation of metallic crystal materials, there is a strong phenomenon of microstructural length refinement, such as dislocation cell size, which is bound to have an important effect on material work hardening and macroscopic plastic flow stress. Based on the inverse relationship between the stress of macroscopic plastic flow and the size of dislocation cell, a new BCJ constitutive model is proposed. Based on the parameters of dislocation cell size, the flow rule of BCJ model and the evolution equation of internal variables are modified. The evolution equation of dislocation cell size considering the correlation of strain rate and temperature is introduced, and the evolution of characteristic length of microstructures is established. Visco-plastic constitutive model of internal variables for dislocation accumulation and annihilation. Using this model, the experimental stress-strain data of OFHC copper at 10-4 103s-1, temperature 298N 542K and strain 0U 1 have been predicted. The results show that the predicted data of this model are in good agreement with the experiment in a wide range of strain rate, temperature and strain. Compared with the BCJ model, the prediction accuracy of the experimental data under different loading conditions is greatly improved, and the maximum average relative error is reduced from 9.939% to 5.525%.
【作者單位】： 昆明理工大學(xué)機(jī)電工程學(xué)院;
【基金】：國家自然科學(xué)基金項目(11462008)
【分類號】：O344.4
，
本文編號：2297353
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