【作者】 苏红娟；

【导师】 董湘怀；

【作者基本信息】 上海交通大学 ， 材料加工工程， 2012， 硕士

【摘要】 本文以大块非晶合金Zr₅₅Al₁₀Cu₅Ni₃₀为研究对象,利用单轴压缩实验研究大块非晶合金在过冷液相区的流变行为,基于虚拟应力模型,通过参数优化和拟合,建立新的、精度较高的本构模型。采用DEFORM-3D有限元分析软件对非晶合金在过冷液相区内进行正挤压成形模拟,分析各类参数对其成形工艺的影响规律,设计和制造微齿轮挤压成形模具,成形出各类齿轮。具体内容如下:（1）通过单轴压缩实验,分析Zr₅₅Al₁₀Cu₅Ni₃₀大块非晶合金在过冷液相区的流变行为,基于虚拟应力模型,利用MATLAB遗传算法优化拟合弹性模量,最大应力和最大松弛时间与温度和应变速率的关系,提高了模型对应力峰值及稳态应力值的计算精度;提出了时间调整因子的概念,提高了对应变变化历史的描述准确度,从而得到描述过冷液相区内不同温度、不同应变速率下非晶合金应力-应变关系的新的本构模型,通过单轴压缩实验与虚拟应力模型计算结果的对比,以及正挤压成形模拟与实验的对比,验证了本构模型的正确性。（2）利用已建立的本构模型,对DEFORM-3D有限元分析模拟软件进行二次开发,将非晶合金本构嵌入到材料库中,并对非晶合金进行正挤压成形模拟,分析挤压比、挤压速度、挤压角度和摩擦条件对非晶合金正挤压成形工艺的影响规律,总结非晶合金理想的成形工艺参数。（3）对非晶合金正挤压成形工艺不同变形阶段,不同挤压角度和不同挤压速度下,流动速度场、等效应力、等效应变和等效应变速率分布进行了有限元分析,为实际应用提供了理论指导。并通过模拟微齿轮挤压成形,找出了实际生产中可能出现的问题,提出了解决方案,保证实验的顺利进行及成形齿轮的表面质量和精度。（4）结合微齿轮成形的特点、模拟结果及实验材料本身的特点,设计和制造与微3K-2型行星齿轮减速器中四种齿轮相对应的两套模具,对关键部件进行表面珩磨处理,保证表面光洁度。通过参数调节和控制,成功挤出四种齿轮,内外齿轮齿形清晰饱满,表面平整,基本满足要求,为微齿轮的大规模塑性加工提供了有力参考。更多还原

【Abstract】 The deformation behavior of Zr₅₅Al₁₀Ni₅Cu₃₀ bulk metallic glass in the supercooled liquid region was investigated in this thesis through the axial compression experiments. Based on fictive stress model, a new constitutive model with high precision was established through the optimization and fitting of parameters. The Micro-forward-extrusion forming of Zr55Al10Ni5Cu30 in the supercooled liquid region was simulated by the finite element analysis software DEFORM-3D. The influences of all kinds of parameters on the forming process have been obtained. At last, the extrusion molds for micro gears were designed and fabricated and micro internal and external gears were extruded successfully.The research work can be summarized as below:（1） The deformation behavior of Zr₅₅Al₁₀Cu₅Ni₃₀ bulk metallic glass in the supercooled liquid region was summarized through the axial compression tests. Based on fictive stress model, the relationships of Young’s modulus, maximum stress and maximum relaxation time with temperature and strain rate were established by using MATLAB Genetic Algorithm, so that the values of stress-overshoot and steady-state could be predicted more precisely. A time adjusting factor was also proposed to better describe the stress history. Thus, a new constitutive model was established to describe the stress-strain curves of bulk metallic glass under different temperatures and strain rates in the supercooled liquid region. Not only the comparison between calculated results of model and axial compression test results, but the comparison between simulation and experiment of micro-forward-extrusion proves the accuracy of the new model.（2） After adding the new constitutive model to the DEFORM-3D, the micro-forward-extrusion experiments of bulk metallic glass were simulated. The influences of extrusion ratio, extrusion velocity, extrusion angle and friction on the forming process have been obtained, so that the optimized process parameters can be got.（3） The finite element analysis of flow velocity field distribution, effective stress, effective strain and effective strain rate of micro-forward-extrusion was conducted under different deformation stages, different extrusion angles and different extrusion velocities, which provided academic guidance for the practical application. Through the simulation of extrusion process of micro gears, the possible problems of actual production were found and the corresponding resolution was also proposed to make sure the experiment runs perfect and guarantee the surface quality and dimension accuracy of formed parts.（4） Considering the forming characters of micro gears, simulation results and the properties of material, two sets of mold were designed and fabricated corresponding to the four kinds of gears of micro 3K-2 planetary gear reducer. The surface of key components is treated by Abrasive Flow Machining to ensure good surface finish. Through the adjustment and control of parameters, four kinds of gears were extruded successfully. The SEM photographs show that both the internal and external gears have clear outline and teeth and the surfaces are smooth, which satisfy the need basically and provide the useful theory reference for the mass plastic production of micro gears.更多还原