(西南交通大學(xué) 應(yīng)用力學(xué)與工程系，成都 610031)
摘 要: 對(duì)6061-T6鋁合金進(jìn)行系統(tǒng)的單軸應(yīng)變循環(huán)和應(yīng)力循環(huán)實(shí)驗(yàn)，揭示該材料在室溫和高溫下的循環(huán)變形行為，討論環(huán)境溫度、加載速率、峰/谷值保持對(duì)其應(yīng)變循環(huán)特性及棘輪行為的影響。結(jié)果表明，6061-T6鋁合金表現(xiàn)出弱的循環(huán)軟化特性，其棘輪行為不僅依賴于平均應(yīng)力和應(yīng)力幅值的大小，還依賴于加載歷史。盡管該合金的單拉行為對(duì)應(yīng)變率的變化不敏感，但其循環(huán)變形行為卻體現(xiàn)出明顯的時(shí)間相關(guān)特性，即：應(yīng)變循環(huán)下，在峰/谷值有保持時(shí)的響應(yīng)應(yīng)力幅值明顯小于沒有保持時(shí)的值，且隨著保持時(shí)間的增加，響應(yīng)應(yīng)力幅值將進(jìn)一步減小；應(yīng)力循環(huán)下，在峰值有保持時(shí)產(chǎn)生的棘輪應(yīng)變比沒有保持時(shí)的值大，且隨著峰值保持時(shí)間的增加及應(yīng)力率的降低，棘輪應(yīng)變明顯增大。
關(guān)鍵字: 6061-T6鋁合金；循環(huán)載荷；棘輪行為；時(shí)間相關(guān)
（Department of Applied Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China）
Abstract:A series of experiments were carried out under uniaxial cyclic straining and cyclic stressing to observe the time-dependent cyclic deformation behaviors of 6061-T6 aluminium alloy at room and elevated temperatures. The main attention was paid to the effects of ambient temperature, loading rate, and peak/valley hold on the strain cyclic characteristics and ratchetting. The results show that 6061-T6 aluminium alloy presents weak cyclic softening feature; the ratchetting behaviour of the material depends not only on the current values of applied mean stress and stress amplitude, but also on their loading histories. Although 6061-T6 aluminium alloy is not sensitive to the variation of strain rate in monotonic tension, its cyclic deformation presents remarkable time-dependence, i.e., the responded stress amplitude in the cyclic straining with peak/valley strain hold is smaller than that obtained without any hold, and decreases further as the hold-time increases; the ratchetting strain produced in the cyclic stressing with peak stress hold is larger than that without any hold and increases as the hold-time increases and the stress rate decreases.
Key words: 6061-T6 aluminium alloy; cyclic loading; ratchetting; time-dependence
