基于分子动力学模拟的超低温SiO_(2)材料开裂影响因素分析

Analysis of Influencing Factors on Cracking of SiO_(2) Materials Based on Molecular Dynamics Simulation at Ultra-low Temperatures

本研究针对岩石主要成分SiO_(2)的常见分子结构,运用LAMMPS分子动力学软件构建了SiO_(2)预制裂纹试样微观尺度下裂纹扩展分析数值模拟模型,分析了不同加载速率、力加载方式、不同温度下力加载及模型厚度条件下的裂纹扩展规律,揭示了超低温下固体材料裂纹起裂扩展的微观影响因素及其规律。研究发现:加载速率变化会引起裂纹扩展路径变化,但不同加载速率下总体势能、动能、区域平均应力以及总体温度的变化规律基本相似;不同温度下力加载,裂纹总长和裂纹平均扩展速率随温度的增加而增加。分子动力学模拟技术能有效反映微观环境对固体介质裂纹扩展的影响规律,为探究岩石类等建筑材料的脆性破坏机理研究提供了新途径。

Aiming at the common molecular structure of SiO_(2),the main component of rock,the numerical simulation model of crack propagation analysis under the micro scale of SiO_(2) prefabricated crack sample is constructed by using lamps molecular dynamics software.The crack propagation laws under different loading rates,force loading methods,force loading at different temperatures and model thickness are analyzed,and the micro influencing factors and laws of crack initiation and propagation of solid materials at ultra-low temperatures are revealed.It is found that the change of loading rate will cause the change of crack propagation path,but the change laws of overall potential energy,kinetic energy,regional average stress and overall temperature are basically similar under different loading rates.Under stress loading at different temperatures,the total crack length and average crack growth rate increase with the increase of temperature.Molecular dynamics simulation can effectively reflect the influence law of micro environment on crack propagation in solid media,and provides a new way to explore the brittle failure mechanism of rock and other building materials.