基于模态柔度的复合材料梁层间损伤识别试验研究

摘要

In this paper,the change ratio of modal flexibility curvature MFCI of composite beam modal was used to discuss the NDT method of composite materials.Firstly, the first three natural frequencies and acceleration amplitudes of the composite beam were tested and calculated through hammering method.Then acceleration amplitude was exchanged to modal displacement amplitude with the method of spectrum conversion.The interlaminar damage of composite beam was detected by calculating the MFCI.The four groups of samples considering damage size,damage location and damage layers were designed and made.The experimental results show that the MFCI 5.200 6 of the damage unit is significantly higher than the average MFCI 0.720 5 of the Non⁃damage unit,the value of abscissa reflects the damage location and mutated spacing shows the size of damage;the MFCI of damage in three different layers are 5.200 6,5.982 8 and 6.883 0,which can indirectly reflect the damage occurred in different interlaminar position.In the multiple damage cases,the damage location can be indentified,but the average value of MFCI 1.192 is much smaller than 5.294 in the single damage case. Due to mutual interference,the multiple damage weakenes the efficiency of damage identification.The exper⁃imental results prove that the method of the change ratio of modal flexibility curvature has the significant effect on the judgment of composite beam interlaminar damage.%利用复合材料梁的模态柔度曲率改变率（MFCI）来探讨复合材料无损检测方法。采用锤击法测量计算出复合材料梁的前三阶固有频率和加速度幅值，并采用频谱转换法将加速度幅值转换成振型位移幅值，计算出复合材料梁的模态柔度曲率改变率（MFCI）值，进而检测出复合材料梁的损伤位置。以损伤的大小、位置、层为要素制作了4组不同工况的对比试件。实验结果表明，损伤单元 MFCI 的值5．2006明显高于各无损伤单元 MFCI 的平均值0．7205，并且它所对应的横坐标的值反映出损伤位置，发生突变单元的间距反映出损伤的大小；3个不同层上损伤 MFCI 的值分别为5．2006、5．9828、6．8830，可间接反映出损伤发生在不同的层间位置上。多损伤的情况下，损伤 MFCI 的平均值为1．192也能识别出损伤位置，但比单损伤 MFCI 的平均值5．294小很多，说明复合多损伤互相干扰，消弱了损伤识别的效率。通过实验证明了模态柔度曲率改变率法对判断复合材料梁的层间损伤有显著效果。