含分层缺陷复合材料夹芯梁力学特性及失效模式的试验研究

Mechanical behavior and failure modes of composite sandwich columns with face/core debond

为研究分层缺陷对复合材料夹层结构承载特性的影响,对含面芯分层缺陷的复合材料夹芯梁开展了系列轴向压缩试验,采用高速摄影仪记录结构的变形形态及破坏过程,对结构出现的欧拉屈曲、剪切屈曲、局部面板褶皱、纤维压缩破坏等失效模式进行分析,并探讨了梁长度、表层厚度、芯层厚度、缺陷尺寸等参数对结构承载特性的影响。试验结果表明:表层厚度对结构的失效模式及承载能力有着直接影响;对于贯穿型矩形缺陷,当缺陷因子μ≥0.05时,结构发生局部屈曲失效;局部屈曲为非稳态失效,当面板出现局部褶皱后,面芯分层缺陷迅速沿轴向向两端扩展,扩展路径可由面芯界面层进入芯层,造成芯层的剪切破坏。

In order to study the effects of face/core debond on load capacity of composite sandwich columns, a series of experimental studies of the in-plane compressive failure mechanism of foam cored sandwich columns with implanted through-width face/core debonds is carried out. The high-speed photography technology is used to provide a visualized insight into the failure mechanisms of compo- site sandwich columns. Four failure modes such as Euler buckling, core shear buckling, face-sheet wrinkling and face-sheet crushing are analyzed. Parametric studies are performed to evaluate the effect of column length, face sheet thickness, core thickness and debond length on the failure mode and ulti- mate load. The observation of response of specimens during testing shows that the face sheet thickness has a direct influence on the failure mode. If the defect factor μ≥0.05, failure occurs with the result of buckling of the debonded face sheet followed by a rapid debond growth towards the ends of the speci- men： Subsequently, extensive cracking and delamination occur in the core which lead to the core crushing and fiber compression failure.