CFRP蒙皮/聚合物泡沫夹芯复合板瞬态响应及其导波无损检测机理研究

Carbon fiber reinforced plastic (CFRP) skin/polymer foam core sandwich composite structures have been widely used in shipbuilding and aircraft industries. These industries cry for efficient and real-time nondestructive testing techniques for them. The ultrasonic guided wave inspection technique for CFRP skin/polymer foam core sandwich composite plates will be studied in this project. Firstly, the characteristic equation of guided waves propagating in the composite plates will be derived using the theory of waves in viscoelastic anisotropic media.The influence of geometrical and material parameters on the dispersion and attenuation of the guided waves will be analyzed based on numerical results. Secondly, the transient response of the composite plates will be studied using the eigenfunction expansion method, based on which the influence of the characteristics of sound sources on the excitation of different guided wave modes will be studied. Furthermore, the guided wave modes used for inspection will be chosen carefully according to the criteria of weak dispersion, weak attenuation and high sensitivity to the defects. Then the excitation control of these modes will be explored. Finally, the interaction between the guided wave modes used for inspection and the defects such as cracks, delaminations and disbonds will be studied. The influence of the size of these defects on the scattered waves will be determined as well as the mechanism of mode conversion. The achievement of this project will lay the groundwork for the guided wave inspection technique of the CFRP skin/polymer foam core sandwich composite plates.

随着碳纤维增强塑料(CFRP)蒙皮/聚合物泡沫夹芯复合材料在船舶及航空工业运用的普及, 相关行业迫切需要发展出针对该复合材料的高效实时检测技术。本项目将围绕CFRP蒙皮/聚合物泡沫夹芯复合板的导波检测技术展开研究。首先，利用黏弹各向异性介质中波传播理论导出CFRP蒙皮/聚合物泡沫夹芯复合板内导波传播的特征方程, 并进行数值求解, 明确复合板几何及材料参数对导波色散及衰减的影响; 其次, 采用本征函数展开法对该复合板瞬态响应进行研究, 明确声源特性对各导波模式激发的影响; 进一步，根据弱色散、弱衰减、对缺陷敏感度高等原则研究检测导波模式的选取, 并探讨其激发控制；最后，利用有限元法对检测导波模式与复合板内断裂、分层、脱粘等缺陷相互作用展开研究，明确不同类型缺陷的尺寸对散射波的影响，并确定模式转换机制。本项目研究成果将为CFRP蒙皮/聚合物泡沫夹芯复合板的导波检测技术奠定坚实的基础。

随着碳纤维增强塑料(CFRP)蒙皮/聚合物泡沫夹芯复合材料在船舶及航空工业运用的普及, 相关行业迫切需要发展出针对该复合材料的高效实时检测技术。本项目围绕CFRP蒙皮/聚合物泡沫夹芯复合板的导波检测技术展开研究。所获成果主要包括以下几点:.1.利用弹性及黏弹横观各向同性介质中波传播理论导出了CFRP蒙皮/聚合物泡沫夹芯复合板中导波色散方程, 并利用Fortran语言编写了数值求解程序;.2 利用本征函数展开法导出了CFRP蒙皮/聚合物泡沫夹芯复合板瞬态动力学响应解,并编写了数值计算程序;.3 根据弱色散、弱衰减、对缺陷敏感度高等原则选取第一与第二阶模式作为检测导波模式, 此外，研究表明, 当外力垂直作用于复合板表面时, 可实现第一阶模式的高效激发, 当外力平行作用于复合板表面时, 可实现第二阶模式的高效激发;.4.利用有限元法对检测导波模式与复合板内断裂、分层、脱粘等缺陷相互作用进行了深入研究;.5.搭建了CFRP蒙皮/聚合物泡沫夹芯复合板导波激发与接收系统，进行了检测导波模式激发及缺陷检测试验。