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This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
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Pavel Strunz Debashis Mukherji Přemysl Beran Ralph Gilles Lukas Karge Michael Hofmann Markus Hoelzel Joachim Rösler Gergely Farkas 《Metals and Materials International》2018,24(5):934-944
An addition of boron largely increases the ductility in polycrystalline high-temperature Co–Re alloys. Therefore, the effect of boron on the alloy structural characteristics is of high importance for the stability of the matrix at operational temperatures. Volume fractions of ε (hexagonal close-packed—hcp), γ (face-centered cubic—fcc) and σ (Cr2Re3 type) phases were measured at ambient and high temperatures (up to 1500 °C) for a boron-containing Co–17Re–23Cr alloy using neutron diffraction. The matrix phase undergoes an allotropic transformation from ε to γ structure at high temperatures, similar to pure cobalt and to the previously investigated, more complex Co–17Re–23Cr–1.2Ta–2.6C alloy. It was determined in this study that the transformation temperature depends on the boron content (0–1000 wt. ppm). Nevertheless, the transformation temperature did not change monotonically with the increase in the boron content but reached a minimum at approximately 200 ppm of boron. A probable reason is the interplay between the amount of boron in the matrix and the amount of σ phase, which binds hcp-stabilizing elements (Cr and Re). Moreover, borides were identified in alloys with high boron content. 相似文献
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B. Schönfelder G. Gottstein L. S. Shvindlerman 《Metallurgical and Materials Transactions A》2006,37(6):1757-1771
While the motion of twist boundaries can be readily studied by atomistic simulations with molecular dynamics (MD) under the
action of an elastic driving force, the approach fails for tilt boundaries. This is due to the interaction of the elastic
stress with the grain boundary (GB) structure, which causes plastic strain by GB sliding. A novel concept, the orientation
correlated driving force, is introduced to circumvent this problem. It is shown that this concept can be successfully applied
to the study of the migration of tilt boundaries. The migration behavior of several twist and tilt GBs was investigated. The
transition from low-to high-angle boundaries can be captured, and a structural transition of tilt boundaries was found at
high temperatures, which also affected the migration behavior. The results compare well with experimental results of the motion
high-angle boundaries, but for low-angle boundaries, the agreement is poor.
This article is based on a presentation made in the “Hillert Symposium on Thermodynamics & Kinetics of Migrating Interfaces
in Steels and Other Complex Alloys,” December 2–3, 2004, organized by The Royal Institute of Technology in Stockholm, Sweden. 相似文献
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A modified natural surfactant was administered to a patient with life-threatening adult respiratory distress syndrome caused by viral pneumonia. Subsequently, there was a marked improvement in gas exchange. In order to assess the mechanism for improved oxygenation, computed tomography of the lungs was done. Quantitative analysis of the scans taken before and after surfactant administration indicates that improvement in gas exchange was largely due to the expansion of underinflated and collapsed lung areas. Although this is a single case report, it provides insight into the possible beneficial effect of instilled surfactant in severe respiratory distress from viral pneumonia. 相似文献
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In the oxidation of TiAl alloys, the role of scale-growth stresses formed during oxidation has, thus far, been unknown. In the present paper the oxide-growth stresses were investigated by the deflection-test method in monofacial oxidation (DTMO) accompanied by acoustic-emission measurements. On unmodified surfaces the growth stresses are compressive and reach levels of around –100 MPa. At the same time, significant acoustic emission occurs indicating that even under isothermal conditions, stresses are relieved by a scale-cracking mechanism. For oxide scales on TiAl surfaces, which had been ion implanted with chlorine before oxidation, a very thin protective alumina layer is formed which, however, develops growth stresses in the range of several GPa, accompanied by intensive acoustic emission. In all stress–time curves, a dynamic situation is observed. This consists of phases of stress relief by scale microcracking and phases of stresses increase due to crack healing and further oxide growth. As a result, the level of stress as a function of oxidation time, is characterized by an oscillating course. 相似文献