基于代表性体积单元的双模铝基复合材料性能拟实研究

Property Simulation of Bimodal Aluminum Matrix Composites Based on the Representative Volume Element Models

目的研究双模铝基复合材料连续区(Continuous Region,CR)和非连续区(Discontinuous Region,DR)力学性能对材料整体力学性能的影响规律,以深入了解双模铝基复合材料的强韧化机理。方法基于Abaqus模拟软件,以双模CNT/Al为研究对象,建立了构型尺度的代表性体积单元(RVE)模型,采用GTN(Gurson-Tvergaard-Needleman)模型来描述双模CNT/Al中CR和DR的变形力学行为,通过定义力学性能参数来简化描述CR和DR复杂的力学性能。针对双模CNT/Al的CR和DR,分别设定力学性能参数HC和HD,并进行一系列的拉伸载荷模拟,研究HC和HD对双模复合材料整体力学性能的影响规律。通过与真实双模CNT/Al的力学性能进行对比,得到双模CNT/Al中CR和DR力学性能与均匀材料力学性能的差异,最后对双模CNT/Al在变形过程中的应力分布情况和断裂后的形貌进行分析。结果当HC小于4时,双模CNT/Al的抗拉强度随HD的增大而下降;当HC大于5时,双模CNT/Al的抗拉强度随HD的增大而增大;双模CNT/Al的屈服强度随着HD和HC的增大而增大,延伸率随着HD和HC的增大而降低。当HD或HC一定时,在HC=HD时,模型材料的延伸率最大。典型双模CNT/Al由“粗晶铝合金+CNT/超细晶Al复合材料”构成,与均匀结构的粗晶铝合金相比,其构型中粗晶铝合金的强度显著提升、塑韧性显著下降;与均匀结构的CNT/超细晶Al相比,其构型中的CNT/超细晶Al复合材料的强度小幅降低、塑韧性小幅提升。当HD大于HC时,裂纹优先在DR产生;当HD小于HC时,裂纹优先在CR区产生;当HD和HC接近时,裂纹产生的区域更加分散。结论建立了一种双模铝基复合材料的有限元模型,从数值上说明了双模CNT/Al复合材料微区与均匀材料的力学性能存在显著差异,为双模铝基复合材料的设计提供了参考。

The work aims to study the effect of the mechanical properties of the continuous region(CR)and the discontinuous region(DR)of bimodal aluminum matrix composites on the overall mechanical performance of the materials,providing theoretical guidance for a deeper understanding of the toughening mechanism of bimodal aluminum matrix composites.Based on the Abaqus simulation software,a representative volume element(RVE)model at the configuration scale was established for the study of bimodal CNT/Al.The GTN(Gurson-Tvergaard-Needleman)model was adopted to describe the deformation mechanics behavior of CR and DR in bimodal CNT/Al,and mechanical performance parameters were defined to simplify the complex mechanical performance parameters of CR and DR.Mechanical performance parameters HC and HD were set for CR and DR of bimodal CNT/Al,and a series of tensile load simulations were conducted to study the effect of HC and HD on the overall mechanical performance of the bimodal composite.By comparing with the real mechanical performance of bimodal CNT/Al,the differences in the mechanical performance exhibited by CRand DR in bimodal CNT/Al and homogeneous materials were obtained.Finally,the stress distribution during the deformation process and the morphology after fracture of bimodal CNT/Al were analyzed.When HC was less than 4,the tensile strength of bimodal CNT/Al decreased with the increase of HD.When HC was greater than 5,the tensile strength of bimodal CNT/Al increased with the increase of HD.The yield strength of bimodal CNT/Al increased with the increase of HD and HC,while the elongation decreased with the increase of HD and HC.When HD or HC was constant,the elongation of the model material was maximum when HC=HD.A typical bimodal CNT/Al consisted of"coarse-grained aluminum alloy+CNT/ultrafine-grained Al composite".In comparison with the uniform structured coarse-grained aluminum alloy in the configuration,it exhibited significantly enhanced strength and significantly reduced ductility.In comparison with the uniform structured CNT/ultrafine-grained Al,the configuration demonstrated a slight decrease in strength and a slight improvement in ductility.When HD was greater than HC,cracks preferentially occurred in the DR.When HD was less than HC,cracks preferentially occurred in the CR region.When HD and HC were close,the area where cracks occurred was more dispersed.A finite element model of bimodal aluminum matrix composites has been established,numerically demonstrating significant differences in the mechanical performance of bimodal CNT/Al composite at the microscale compared to homogeneous materials,providing reference guidance for the design of bimodal aluminum matrix composites.