颗粒增强铝基复合材料损伤演化模型的建立与强力旋压数值模拟

发布时间：2018-02-23 04:12

本文关键词： 颗粒增强铝基复合材料本构方程损伤演化模型强力旋压数值模拟　出处：《北京有色金属研究总院》2015年硕士论文　论文类型：学位论文

【摘要】：颗粒增强铝基复合材料具有高比强度、高比刚度、高耐磨性、高尺寸稳定性、低密度和低热膨胀系数等一系列优异的综合性能,在先进武器装备和航天技术领域有良好应用前景。强力旋压具有材料利用率高、加工灵活、适合制造大径厚比管材等优势,是加工复合材料管材的有效方法。颗粒增强铝基复合材料在强力旋压加工过程中,由于增强体的存在,基体的连续性容易被破坏,其塑性会降低,成形零件不可避免会产生内部微裂纹,即为损伤。微裂纹不断长大和汇合,最终会引发复合材料的宏观断裂。本文采用建立复合材料损伤演化模型和数值模拟相结合的方式,预测复合材料在高温变形过程中的宏观断裂现象以及强力旋压加工过程中损伤值的变化规律,为实际生产工艺制定和优化提供理论依据。本文对颗粒增强铝基复合材料进行了热模拟实验,得到了该材料高温变形条件下的应力应变曲线,建立了材料的高温本构方程,计算了本构方程的相关参数,并对本构方程进行了实验对比验证,结果显示误差值为3.8%,说明该本构方程能够较好的描述复合材料的高温流变行为。基于连续损伤力学理论,考虑变形温度和应变速率的影响,建立了颗粒增强铝基复合材料高温变形过程中的损伤演化模型。利用Lemaitre提出的弹性模量法进行高温多道次拉伸实验,得到了复合材料不同变形条件下的损伤演化曲线。对损伤演化曲线数据拟合确定了模型参数为A(Z)=2.22769-0.09438In Z+0.00238ln2 Z,对损伤临界值拟合确定了复合材料宏观断裂的判断依据为DC(Z)=0.50915-0.00577ln Z。采用高温压缩实验对损伤演化模型进行验证,结果表明该模型可以较好的预测复合材料在高温变形过程中的宏观断裂现象。基于模拟软件,建立了颗粒增强铝基复合材料强力旋压有限元模型。在软件中耦合了损伤演化模型,并导入了损伤参数。通过数值模拟,分析了复合材料强力旋压过程中应力应变的变化规律,旋轮接触区三向应力的大小,材料流动的稳定性以及损伤值的变化规律。并讨论了不同旋压温度、减薄率和进给比对复合材料强力旋压等效应力和损伤值的影响。结果显示损伤值随温度的升高而降低,随减薄率的增加而升高,随进给比的增加而升高。绘制了损伤值的三维曲面,通过曲面图可以选择材料加工的安全参数范围,避免材料发生宏观断裂。通过物理实验对数值模拟的预测进行验证,结果较为吻合。
[Abstract]:Particle reinforced aluminum matrix composites have a series of excellent properties, such as high specific strength, high specific stiffness, high wear resistance, high dimensional stability, low density and low coefficient of thermal expansion. It has a good application prospect in the field of advanced weapon equipment and aerospace technology. Strong spinning has the advantages of high material utilization ratio, flexible processing, suitable for manufacturing large diameter to thickness ratio pipe, etc. Particle reinforced aluminum matrix composites are easy to be destroyed because of the existence of reinforcements, and their plasticity will be reduced. It is inevitable that the forming parts will produce internal microcracks, that is, damage. The microcracks will grow and converge, which will eventually lead to the macroscopic fracture of composite materials. In this paper, the damage evolution model and numerical simulation of composite materials are established by combining the damage evolution model and numerical simulation. The macroscopic fracture phenomenon of composites during high temperature deformation and the variation of damage value during the process of strength spinning are predicted. In this paper, the thermal simulation experiments of particle reinforced aluminum matrix composites are carried out, the stress-strain curves of the materials under high temperature deformation are obtained, and the constitutive equations of the materials at high temperature are established. The related parameters of the constitutive equation are calculated, and the experimental results show that the error is 3.8. the result shows that the constitutive equation can describe the rheological behavior of composites at high temperature. Based on the theory of continuous damage mechanics, the constitutive equation can describe the rheological behavior of composites at high temperature. Considering the influence of deformation temperature and strain rate, the damage evolution model of grain reinforced aluminum matrix composites during high temperature deformation was established. The elastic modulus method proposed by Lemaitre was used to carry out multi-pass tensile tests at high temperature. The damage evolution curves of composite materials under different deformation conditions were obtained, and the model parameters were determined as Agna 2.22769-0.09438In Z 0.00238ln2Z by fitting the data of damage evolution curves, and the judgment basis for the macroscopic fracture of composites was determined as follows: 1. DC(Z)=0.50915-0.00577ln Z. the damage evolution model is verified by high temperature compression test. The results show that the model can be used to predict the macroscopic fracture of composites during high temperature deformation. In this paper, a finite element model for the strength spinning of particle reinforced aluminum matrix composites is established. The damage evolution model is coupled in the software, and the damage parameters are introduced. Through numerical simulation, the variation of stress and strain in the process of strength spinning of the composite is analyzed. The magnitude of triaxial stress in the contact zone of rotary wheel, the stability of material flow and the variation of damage value are discussed, and the different spinning temperatures are discussed. The effect of thinning rate and feed ratio on the equivalent stress and damage value of the composite strength spinning shows that the damage value decreases with the increase of temperature and increases with the increase of thinning rate. With the increase of feed ratio, the 3D surface with damage value is drawn, and the safety parameter range of material processing can be selected by the surface diagram, which can avoid the macroscopic fracture of material. The prediction of numerical simulation is verified by physical experiments. The results are in good agreement.
【学位授予单位】：北京有色金属研究总院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB333

【参考文献】