1,636 research outputs found
Mixed-mode cyclic debonding of adhesively bonded composite joints
A combined experimental-analytical investigation to characterize the cyclic failure mechanism of a simple composite-to-composite bonded joint is conducted. The cracked lap shear (CLS) specimens of graphite/epoxy adherend bonded with EC-3445 adhesive are tested under combined mode 1 and 2 loading. In all specimens tested, fatigue failure occurs in the form of cyclic debonding. The cyclic debond growth rates are measured. The finite element analysis is employed to compute the mode 1, mode 2, and total strain energy release rates (i.e., GI, GII, and GT). A wide range of mixed-mode loading, i.e., GI/GII ranging from 0.03 to 0.38, is obtained. The total strain energy release rate, G sub T, appeared to be the driving parameter for cyclic debonding in the tested composite bonded system
Interaction of mixed mode loading on cyclic debonding in adhesively bonded composite joints
A combined experimental and analytical investigation of an adhesively-bonded composite joint was conducted to characterize the fracture mode dependence of cyclic debonding. The system studied consisted of graphite/epoxy adherends bonded with EC 3445 adhesive. Several types of specimens are tested which provide the cyclic debond growth rate measurements under various load conditions: mode 1, mixed mode 1 to 2, and mostly mode 2. This study shows that the total strain-energy-release rate is the governing factor for cyclic debonding
Cyclic debonding of adhesively bonded composites
The fatigue behavior of a simple composite to composite bonded joint was analyzed. The cracked lap shear specimen subjected to constant amplitude cyclic loading was studied. Two specimen geometries were tested for each bonded system: (1) a strap adherend of 16 plies bonded to a lap adherend of 8 plies; and (2) a strap adherend of 8 plies bonded to a lap adherend of 16 plies. In all specimens the fatigue failure was in the form of cyclic debonding with some 0 deg fiber pull off from the strap adherend. The debond always grew in the region of adhesive that had the highest mode (peel) loading and that region was close to the adhesive strap interface
Sexual reproduction of yellow ecotype of Neurospora intermedia in nature
The vegetative stage of yellow ecotype of Neurospora intermedia occurs on various substrates but there has been no evidence of its telomorphic stage in nature. This paper presents evidence for the sexual reproduction of this ecotype in nature on maize cobs
Mid infrared polarization engineering via sub-wavelength biaxial hyperbolic van der Waals crystals
Mid-infrared (IR) spectral region is of immense importance for astronomy, medical diagnosis, security and imaging due to the existence of the vibrational modes of many important molecules in this spectral range. Therefore, there is a particular interest in miniaturization and integration of IR optical components. To this end, 2D van der Waals (vdW) crystals have shown great potential owing to their ease of integration with other optoelectronic platforms and room temperature operation. Recently, 2D vdW crystals of α-MoO3 and α-V2O5 have been shown to possess the unique phenomenon of natural in-plane biaxial hyperbolicity in the mid-infrared frequency regime at room temperature. Here, we report a unique application of this in-plane hyperbolicity for designing highly efficient, lithography free and extremely subwavelength mid-IR photonic devices for polarization engineering. In particular, we show the possibility of a significant reduction in the device footprint while maintaining an enormous extinction ratio from α-MoO3 and α-V2 O5 based mid-IR polarizers. Furthermore, we investigate the application of sub-wavelength thin films of these vdW crystals towards engineering the polarization state of incident mid-IR light via precise control of polarization rotation, ellipticity and relative phase. We explain our results using natural in-plane hyperbolic anisotropy of α-MoO3 and α-V2 O5 via both analytical and full-wave electromagnetic simulations. This work provides a lithography free alternative for miniaturized mid-infrared photonic devices using the hyperbolic anisotropy of α-MoO3 and α-V2 O5
A Boy Named Courage: A Surgeon’s Memoir of Apartheid. By Himmet Dajee with Patrice Apodaca. Malvern, Penn.: Cynren Press, 2018. ISBN-13: 978-1-947976-00-9 (hbk)
This is a review of a book written by an ex-South African cardiothoracic surgeon of Indian origin who laments the fact that his own country could not allow him to study here
Origin of Ferroelectricity in Orthorhombic LuFeO
We demonstrate that small but finite ferroelectric polarization (0.01
C/cm) emerges in orthorhombic LuFeO () at (600
K) because of commensurate (k = 0) and collinear magnetic structure. The
synchrotron x-ray and neutron diffraction data suggest that the polarization
could originate from enhanced bond covalency together with subtle contribution
from lattice. The theoretical calculations indicate enhancement of bond
covalency as well as the possibility of structural transition to the polar
phase below . The phase, in fact, is found to be
energetically favorable below in orthorhombic LuFeO ( with
very small energy difference) than in isostructural and nonferroelectric
LaFeO or NdFeO. Application of electric field induces finite
piezostriction in LuFeO via electrostriction resulting in clear domain
contrast images in piezoresponse force microscopy.Comment: 12 pages, 8 figure
Cohomology of bundles on homological Hopf manifold
We discuss the properties of complex manifolds having rational homology of
including those constructed by Hopf, Kodaira and
Brieskorn-van de Ven. We extend certain previously known vanishing properties
of cohomology of bundles on such manifolds.As an application we consider
degeneration of Hodge-deRham spectral sequence in this non Kahler setting.Comment: To appear in Proceedings of 2007 conference on Several complex
variables and Complex Geometry. Xiamen. Chin
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