Inspection of defects in CFRP-Foam Layered structure composite plates of aerospace materials using lock-in thermography

This study is performed experimentally to investigate damage forces formed on glass-fibre laminated composite plates that are jointed with a component in the shape of butterfly. Pressing it into the mould in a hot press machine produced a glass fibre-epoxy composite plate. Specimens and locking parts in the shape of butterfly were cut using water jet. Experiments were performed in different values of the ratio of the end width of butterfly to the width of the specimen ( w/ b), the ratio of the middle width of butterfly to the end width of butterfly ( x/ w) and the ratio of the half-length of butterfly to the width of the specimen ( y/ b). Using these values, the effects of joint geometry parameters were evaluated. To be able to see the effect of material variations as well, the joint lock in the shape of butterfly was made up of both metal and composite materials. Although the loading capacity of the composite butterfly is lower than that of the metal butterfly, it carries loads for much longer times. Before a composite structure develops damage, damage occurred in the composite butterfly can be seen and, with the repair of the butterfly lock, the life of the composite structure can be extended.

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In situ TEM Studies of agglomeration of sub-nanometer Ru layers in Ru/C multilayers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100121685 ◽

1992 ◽

Vol 50 (1) ◽

pp. 256-257

Author(s):

Tai D. Nguyen ◽

Ronald Gronsky ◽

Jeffrey B. Kortright

Keyword(s):

Layered Structure ◽

Driving Force ◽

High Energy ◽

Superior Performance ◽

In Situ Tem ◽

Rayleigh Instability ◽

Practical Applications ◽

Transmission Electron ◽

Diffraction Patterns

Nanometer period Ru/C multilayers are one of the prime candidates for normal incident reflecting mirrors at wavelengths < 10 nm. Superior performance, which requires uniform layers and smooth interfaces, and high stability of the layered structure under thermal loadings are some of the demands in practical applications. Previous studies however show that the Ru layers in the 2 nm period Ru/C multilayer agglomerate upon moderate annealing, and the layered structure is no longer retained. This agglomeration and crystallization of the Ru layers upon annealing to form almost spherical crystallites is a result of the reduction of surface or interfacial energy from die amorphous high energy non-equilibrium state of the as-prepared sample dirough diffusive arrangements of the atoms. Proposed models for mechanism of thin film agglomeration include one analogous to Rayleigh instability, and grain boundary grooving in polycrystalline films. These models however are not necessarily appropriate to explain for the agglomeration in the sub-nanometer amorphous Ru layers in Ru/C multilayers. The Ru-C phase diagram shows a wide miscible gap, which indicates the preference of phase separation between these two materials and provides an additional driving force for agglomeration. In this paper, we study the evolution of the microstructures and layered structure via in-situ Transmission Electron Microscopy (TEM), and attempt to determine the order of occurence of agglomeration and crystallization in the Ru layers by observing the diffraction patterns.

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