玻璃钢激光烧蚀碳化致微波传输衰减的数值模拟

当激光辐照玻璃钢烧蚀碳化至一定程度时，产生的树脂碳产物对微波传输产生衰减作用。针对该现象，开展了数值建模研究，将激光辐照-微波传输衰减效应分解为激光辐照、材料热响应、提取模型表征量、微波传输衰减分析等过程。通过玻璃钢材料的激光耦合特性和表面温度测试，对建立的玻璃钢层合板激光辐照温度场计算模型进行了验证；通过材料体温度分布的时间演进分析，提取了网格单元温度超过阈值温度的持续时间加权和S_{t, Tc}、网格单元温度超过阈值温度的持续时间与温度乘积的加权和S_{Tt, Tc}两个模型表征量，采用单个实验数据标定系数、整体数据点匹配分析方法，对微波传输衰减实验与数值模拟结果进行了分析。分析结果表明，S_{t, Tc}比S_{Tt, Tc}更适于表征玻璃钢烧蚀碳化致微波传输衰减效应，温度阈值为873 ℃时计算结果与实验结果最匹配，其R2为0.9956。这说明，通过计算激光辐照玻璃钢温度响应并提取微波传输衰减效应表征量S_{t, Tc}，可实现对玻璃钢激光烧蚀碳化致微波传输衰减效应的模拟和预测。

Numerical simulation of ablation and carbonization of GFRP irradiated by laser induced microwave transmission decay

It is found that ablation and carbonization of GFRP irradiated by laser will induce microwave transmission decay since some char products appear. To study this phenomenon, a numerical simulation investigation was carried out, which was considered composing of laser irradiating, material thermal response, characteristics quantity modeling, and microwave transmission decay analysis. A temperature calculation numerical model of GFRP laminated plate irradiated by laser was built and validated by measuring its laser coupling characteristics and surface temperature. By analyzing the temporal evolution process of GFRP volumetric temperature field, two model characteristics quantities were built: weighted sum of duration time of mesh elements temperature exceed-ing threshold temperature T_c, described as S_{t, Tc}, and weighted sum of product of temperature and duration time of mesh elements temperature exceeding threshold temperature, described as S_{Tt, Tc}. The experiment and numerical simulation results of microwave transmission decay were analyzed, applying a method which calibrated the model characteristics quantities by a selected experimental result, and analyzed matching deviation of the entire data. It is found that, S_{t, Tc} is well characterizing the microwave transmission decay effect of GFRP rather than S_{Tt, Tc}, and the best matching result of R2 is 0.9956 when the temperature threshold is 873 ℃. It is demonstrated that the model can simulate and predict the microwave transmission decay by calculating the temperature response of GFRP irradiated by laser and distilling S_{t, Tc} from the volumetric temperature temporal evolution.