分子动力学模拟在电缆绝缘护套材料损伤与修复机理研究的应用

Application of Molecular Dynamics Simulation in the Study of Damage and Repair Mechanism of Cable Insulation Sheath Materials

电缆绝缘护套在敷设、使用过程中受到机械损应力或者热应力等因素的影响会产生微裂纹损伤,如不及时修复,容易导致其机械与绝缘性能快速下降,使材料性能失效,甚至引发线路故障。基于分子动力学理论揭示电缆绝缘护套材料损伤的机理,通过分子动力学模拟计算得到护套材料在损伤自由体积与内聚能变化规律,并分析损伤对材料绝缘性能的影响以及微裂纹产生的机理。针对常规的聚乙烯等电缆护套材料不具备自修复性能的问题,研发电缆护套自修复材料,在材料中引入解离结合可逆的自修复功能基团,当材料损伤时,通过功能基团重新结合达到修复的目的。应用分子动力学对新材料进行模拟计算的结果表明,通过自修复后材料的自由体积降低,内聚能密度提高23%,溶解度参数提高10.9%,证明了新材料自修复的有效性。

During the laying and use of cable insulating sheaths,they are inevitably affected by mechanical or thermal stress,which can cause microcrack damage.If not repaired in a timely manner,the damage can easily lead to a rapid decline in their mechanical and insulation properties,material performance failure,and even circuit faults.This paper reveals the mechanism of damage to cable insulation sheath materials based on molecular dynamics theory.Through molecular dynamics simulation calculations,the changes in the free volume and cohesive energy of the sheath material under damage are obtained.The influence of damage on the insulation performance of the material and the mechanism of microcracks are also analyzed from the perspective of molecular dynamics theory.Due to the lack of self-healing properties in conventional polyethylene and other cable sheath materials,cracks are difficult to repair in a timely manner,resulting in a gradual loss of performance.Therefore,the development of cable sheath self-healing materials introduces reversible host guest self-healing functional groups that dissociate and bind into the material.When the material is damaged,the purpose of repair is achieved through the recombination of functional groups.The results of simulating the new material using molecular dynamics show that after self-healing,the free volume of the material decreases,the cohesive energy density increases by 23%,and the solubility parameter increases by 10.9%,demonstrating the effectiveness of self-healing.