AA6082鋁合金熱變形損傷本構(gòu)模型Damage constitutive model for thermal deformation of AA6082 aluminum alloy

利用Gleeble-1500熱力模擬試驗機在溫度為425~525 ℃、應(yīng)變速率為0.01~1 s^-1條件下對AA6082鋁合金進行熱拉伸試驗，研究該合金的熱變形行為。結(jié)果表明：變形溫度、應(yīng)變速率和應(yīng)變對AA6082鋁合金的流變應(yīng)力影響顯著，流變應(yīng)力隨變形溫度的升高而下降，隨應(yīng)變速率的提高而增加；材料熱變形經(jīng)歷了應(yīng)變硬化段、穩(wěn)態(tài)變形段和由損傷引起的流變應(yīng)力陡降段。建立AA6082鋁合金熱變形統(tǒng)一黏塑性損傷本構(gòu)模型，該模型綜合考慮位錯、硬化、損傷、應(yīng)變、應(yīng)變速率和溫度等因素，借助遺傳算法工具箱確定模型中材料常數(shù)。該模型能夠較好地預(yù)測AA6082鋁合金熱變形時的流變應(yīng)力，同時可以較好地描述材料的損傷演化行為。

Thermal deformation tests of AA6082 aluminum alloy were conducted by thermal-mechanical simulator Gleeble-1500 in the temperature range of 425-525 ℃ and strain rate of 0.01-1 s^-1 to investigate the thermal deformation behavior. The results show that the flow stress of AA6082 aluminum alloy is significantly influenced by temperature, strain rate and strain. The flow stress increases with decreasing temperature and increasing strain rate. The thermal deformation goes through strain hardening, steady-state stage and steep-fall stage of flow stress. The unified viscoplastic damage model of AA6082 aluminum alloy was established, taking into account of many factors, such as dislocation, hardening, damage, strain, strain rate and temperature. Material constants in the model were determined by genetic algorithm tool. The model can accurately predict the flow stress of AA6082 aluminum alloy in thermal deformation and describe the damage evolution.

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