基于分子动力学和扩展有限元的金属微胶囊破裂性研究

Study on cracking performance of metal microcapsules based on molecular dynamics and extended finite element method

在树脂矿物复合材料中掺入微胶囊实现材料自愈得到了广泛应用,而新出现的金属微胶囊解决了传统微胶囊力学和鲁棒等性能较差的问题。但因金属微胶囊与基体间的界面力学性能尚未可知,使其破裂性无法确定,进而无法将金属微胶囊推广。针对这一问题,本文提出利用分子动力学方法对金属微胶囊的囊壁/树脂基体界面损伤演化过程进行模拟,获得界面力学性能。以此为基础,运用扩展有限元对金属微胶囊的破裂性进行分析,为金属微胶囊的运用提供研究指导和理论依据。研究结果表明:(1)分子动力学模拟囊壁/基体界面模型损伤演化过程可以分为初始变形、局部破坏和整体破坏3个过程;(2)囊壁/基体界面弹性模量为6.458 GPa,强度极限为62 MPa;(3)金属微胶囊只会在基体裂纹出现后破损,但破损时间早于基体裂纹到达金属微胶囊处。

Microcapsules are widely used in resin mineral composites to achieve self-healing.The new metallic microcapsules solve the problems of poor mechanical and robustness of traditional microcapsules.However,because the mechanical properties of the interface between the metallic microcapsules and the matrix are unknown,the cracking performance of the metallic microcapsules cannot be determined.As a result,it is difficult to determine the practicability of metallic microcapsules,and thus unable to promote them.To solve this problem,molecular dynamics method was proposed to simulate the damage evolution process of metal microcapsule wall/resin matrix interface,and obtain the interface mechanical properties.On this basis,the cracking performance of metal microcapsules was analyzed by using the extended finite element method and the cohesive force model.The results show that:(1)The damage evolution process of the model can be divided into three processes:Initial deformation,local failure and global failure;(2)The elastic modulus of the capsule wall/matrix interface is 6.458 GPa,and the strength limit is 62 MPa;(3)The metal microcapsules can break after the matrix crack appears,but earlier than the matrix crack reaches the metal microcapsules.The results provide a theoretical basis for the application of this new metal microcapsule.