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为了给复合材料结构的调制热波成像检测提供基础理论依据和操作参数窗口,用基于有限单元法的计算机数值模拟研究了复合材料层压板分层、脱粘的调制热像检测规律。分析了相位差与调制频率及缺陷深度的关系,提出了最佳检测频率、半高频带和盲频的预测方法,验证了利用盲频来估计缺陷深度的方法,提出利用最佳检测频率来估计缺陷深度的新方法。研究结果表明:最佳调制频率和盲频近似与缺陷深度的平方成反比;最大相位差及半高频带宽随缺陷深度的增大而减小;利用盲频和最佳调制频率都可以对缺陷深度进行定量估计,在缺陷深度为1~4mm的范围内,两种方法的估计误差分别在约9%和11%以内。
In order to provide the theoretical basis and operating parameters window for the modulated thermo-wave imaging of composite structures, the thermo-graphic detection rules of layered and debonded composite laminates were studied by computer numerical simulation based on finite element method. The relationship between phase difference, modulation frequency and defect depth is analyzed. The optimal detection frequency, half-high frequency band and blind frequency prediction method are proposed. The method to estimate the defect depth by blind frequency is validated. The optimal detection frequency A new method of estimating the depth of defects. The results show that the optimal modulation frequency and the blind frequency approximation are inversely proportional to the square of the depth of the defect. The maximum phase difference and half-height bandwidth decrease with the increase of the defect depth. Both the blind frequency and the optimal modulation frequency The depth of quantitative estimation, the defect depth of 1 ~ 4mm range, the estimated error of the two methods are about 9% and 11%.