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基于非线性强度特征的深埋隧道围岩有限应变求解
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作者 陈嘉骏 路喆津 +2 位作者 孟超 胡世红 赵炼恒 《铁道科学与工程学报》 EI CAS CSCD 北大核心 2024年第10期4148-4160,共13页
深埋隧道的围岩强度随着围压的增大而呈现出明显的非线性变化,且其具有高地应力这一显著特征使得准确评估隧道掘进过程中围岩的力学响应难以实现。引入岩石的非线性强度特征,建立深埋隧道围岩的对数应变方程,并考虑已有研究中大多忽略... 深埋隧道的围岩强度随着围压的增大而呈现出明显的非线性变化,且其具有高地应力这一显著特征使得准确评估隧道掘进过程中围岩的力学响应难以实现。引入岩石的非线性强度特征,建立深埋隧道围岩的对数应变方程,并考虑已有研究中大多忽略的岩石应变硬化特性,在有限差分循环迭代过程中使用当前节点的塑性剪切应变进行内部变量求解,提出基于统一应变硬化−应变软化本构模型和非线性剪胀模型的围岩弹塑性耦合有限应变解析方法。模型退化为小应变分析时,解析结果与经典理论解答基本一致,可以验证方法的有效性。影响参数分析表明:忽略岩石剪胀系数的非线性衰减将低估有限应变围岩的塑性区范围;随岩石剪胀特性的增强,洞壁位移、残余区半径和塑性区半径逐渐增加,且其增加幅度随围压减小而明显。岩石应变软化特性主要影响围岩残余区和软化区的占比,引起围岩位移的变化,其特性增强将显著减小塑性区半径。是否考虑岩石应变硬化特性对围岩塑性区范围的评估至关重要,但应变硬化特性的增强对塑性区的半径影响较小,其特性增强主要表现为对围岩软化区和硬化区占比的改变。采用该方法可有效评估深埋隧道有限应变围岩的塑性区范围,并为支护结构体系的设计提供理论指导。 展开更多
关键词 非线性强度特征 剪胀特性 应变硬化−应变软化 深埋隧道 有限应变
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Effect of strain rate and deformation temperature on strain hardening and softening behavior of pure copper 被引量:4
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作者 黄树海 舒大禹 +1 位作者 胡传凯 朱世凤 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第4期1044-1054,共11页
The effects of the deformation temperature and the strain rate on the hot deformation behavior of pure copper were investigated based on compression tests. The expressions of strain hardening rate, dynamic recrystalli... The effects of the deformation temperature and the strain rate on the hot deformation behavior of pure copper were investigated based on compression tests. The expressions of strain hardening rate, dynamic recrystallization critical stress, saturated stress, dynamic recovery volume fraction and dynamic recrystallization volume fraction were determined. According to the processing map, the instability regions occur in regions of 400?450 °C, 0.001?0.05 s?1 and 450?750 °C, 0.05?1 s?1. The deformation mechanism in the stability region is dynamic recrystallization. The flow stress was predicted. The results also show that the true stress–true strain curves predicted by the extracted model are in good agreement with the experimental results. 展开更多
关键词 COPPER hot compression deformation strain hardening strain softening
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Effect of strain hardening and strain softening on welding distortion and residual stress of A7N01-T4 aluminum alloy by simulation analysis 被引量:8
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作者 闫德俊 刘雪松 +2 位作者 李军 杨建国 方洪渊 《Journal of Central South University》 SCIE EI CAS 2010年第4期666-673,共8页
The effect of strain hardening and strain softening behavior of flow stress changing with temperature on welding residual stress, plastic strain and welding distortion of ATN0 1-T4 aluminum alloy was studied by finite... The effect of strain hardening and strain softening behavior of flow stress changing with temperature on welding residual stress, plastic strain and welding distortion of ATN0 1-T4 aluminum alloy was studied by finite simulation method. The simulation results show that the weld seam undergoes strain hardening in the temperature range of 180-250 ℃, however, it exhibits strain softening at temperature above 250 ℃ during welding heating and cooling process. As a result, the strain hardening and strain softening effects counteract each other, introducing slightly influence on the welding residual stress, residual plastic strain and distortion. The welding longitudinal residual stress was determined by ultrasonic stress measurement method for the flat plates of A7N01-T4 aluminum alloy. The simulation results are well accordant with test ones. 展开更多
关键词 strain hardening strain softening plastic strain welding residual stress
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