轻骨料水泥基多功能吸波材料的制备及有限元分析

Preparation and Finite Element Analysis of Lightweight Aggregate Cement-based Multi-function Absorbing Materials

为分析轻骨料种类及粒径对吸波材料性能的影响,采用五种从微米级至毫米级粒径的轻骨料制备了轻质水泥基吸波材料,测试其电磁参数和反射损耗(RL),采用有限元分析方法构建了二维截面模型,模拟吸波材料内部电磁场分布情况,并测试了吸波材料的力学性能和导热系数。结果表明,增加轻骨料掺量和增大粒径可改善水泥基材料的阻抗匹配性能,提升平均RL,拓宽有效吸波频宽,吸收峰向高频移动。20 mm厚度时,吸波材料在低频1.2 GHz处最优RL为-29.1 dB,在较高频5.9 GHz处最优RL为-20.9 dB,有效吸波频宽最宽可达14.49 GHz。有限元模拟结果表明,轻骨料可改变电磁波传输方向,增加电磁波损耗途径,相邻骨料之间可产生较强损耗,其次是在骨料内部产生损耗,这为骨料种类、粒径选择与轻质吸波材料设计提供理论基础。增大轻骨料粒径会降低吸波材料的密度、力学强度与导热系数,使其吸波效能更好,保温效果更优。

In order to analyze the effects of lightweight aggregate type and particle size on the properties of wave absorbing materials,five kinds of lightweight aggregate with particle sizes ranging from micron to millimeter were used to prepare lightweight cement-based absorbing materials,and their electromagnetic parameters and reflection loss(RL)were tested.2D cross-section model was constructed by finite element analysis method to simulate the electromagnetic field distribution inside the wave absorbing materials.The mechanical properties and thermal conductivity of the wave absorbing materials were tested.The results show that the impedance matching performance of cement-based materials and the average RL are improved via increasing the content of lightweight aggregate and particle size,as well as broaden the effective absorption bandwidth,and the absorption peak is moved to high frequency.When the thickness is 20 mm,the optimal RL of the wave absorbing material is-29.1 dB at the low frequency of 1.2 GHz and-20.9 dB at the high frequency of 5.9 GHz,and the maximum effective absorbing bandwidth can reach 14.49 GHz.The finite element simulation results show that the electromagnetic wave transmission direction can be changed by adding lightweight aggregate,the electromagnetic wave loss path is increased,and a strong loss is produced between neighboring aggregates,then the loss occurs inside aggregate,which provides a theoretical basis for the selection of aggregate type,particle size and the design of lightweight absor-bing materials.The density,mechanical strength and thermal conductivity of wave absorbing materials are reduced via increasing the particle size of lightweight aggregate,the wave absorption efficiency and the heat preservation effect are better.