Crack Damage Effect Of Sandwich Structure With Different Interfacial Delamination Size

Sandwich structures are mostly made of thin and stiff face sheets and weaker core. For the different kinds of core and face, sandwich structures have several types : foam sandwich structure ,honeycomb sandwich structure and echelon sandwich structure. The face/core debond is most severe for sandwich structure loaded in compression. It decreases the load bearing ability and the life of the structure drastically and probably leads to heavy accident. With the broad application of sandwich structures in aviation and other engineering domain, the research of these sandwich structures which have debond or damnification become very important. At present, the focus of the research about sandwich structures are impact damnification, debond damnification and so on.The purpose of this paper is to predict the mechanical behavior and the propagation of the debond of a pure bend panel containing a face/core debond. This research use the FEA software ANSYS to simulate the mechanical behavior and the propagation of the debond of the four-point bend panel. This paper is concentrates on the mechanical behavior of different debond area under the pure bend condition. The three dimension spring element is used to simulate the glue between face/core, Two sets tangential to the face and the other set normal to the face sheet. Comparing the effect of this paper between element Solid45 and Solid95, we can find that the Solid95 element is superior. For the compression loaded panel which has ellipse debond, much more refined study about the effect of the first cracking place under different ratio of short axis to long axis is investigated. There exist a ratio whether the length of long axis or short axis of the ellipse is constant, the first cracking place changed at this ratio, and the ratio changed with the length of long or short axis. Through studying the propagation of the debond when sandwich structures under four-point bending and analyzing the influence of propagation of the debond in distinct condition Such as different size of debond area and the attribute of core and face, the conclusion is that the ratio of the face Young's modulus to the core Young's modulus is invert proportional with the load of the propagation of debond. This paper is also discussed the effect of glue with different attribute. The attribute of glue has little influence to the load of the propagation of debond. At last, comparing with perfect sandwich structure, the sandwich structures which have face/core debond take more dangerous. The conclusion of simulate is basically coincident with experiment data. During the research, we find and summarized some rules and tendencies, provided some useful according to deeper and subsequent research.