National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

Transformation of hydrothermally derived nanowire cluster intermediates into CdSiO3 nanobelts

Abstract: In this communication, we demonstrate that cadmium metasilicate nanobelts could be fabricated via a facile, eco-friendly, low cost hydrothermal treatment in the absence of surfactants and organic additives, followed by calcination. The monoclinic phase formation of the sample is described in detail by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and fourier transform infrared (FT-IR) studies. The field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) measurements of as-formed samples and samples calcined at 600 °C for 3 h indicate that the as-formed CdSiO3 sample consists of entangled nano-wire bundles with diameters ranging from 20 to 80 nm and lengths in the order of several micrometers. The calcined sample consists of nanobelts of slightly increased diameter and increased length compared to the as-formed samples. The selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) images reflect the polycrystalline nature of nanobelts. The probable mechanism for the formation of nanobelts is also discussed.

Low velocity impact damage tolerance studies on glass-epoxy laminates - Effects of material, process and test parameters

Abstract: An effort has been made to study the effects of variable incident impact energy and laminate thickness (obtained by varying the number of fabric layers at constant moulding pressure and also by varying the pressure for a fixed number of fabric layers), on the low velocity impact damage tolerance of GFRP composite laminates (woven E-glass fabric in a room temperature cure epoxy system LY556/HY951) Repeated drop tests were conducted using an in-house built drop weight impact tester Number of drops to failure (Nf), was considered as the impact damage tolerance index Correlations between Nf and composite material parameters (fiber weight fraction - Wf, laminate thickness - t, number of fabric layers - L) and a test parameter (incident impact energy - E) were found out and the bounding limits for these were defined Critical values of impact energy (Ec) and laminate thickness (tc) were defined (for the particular resin - hardener system chosen for the study) which can quite possibly be used as designer's guidelines A new ratio, (t/Wf), was introduced for the study of composite systems where both fiber weight fraction and laminate thickness get affected upon alteration of a process parameter (the pressure - P as in this case)

Comparative Study of Different Pressure-Sensitive-Paint Image Registration Techniques

Abstract: Image alignment plays an important role in pressure-sensitive-paint (PSP) data processing. A systematic comparative13; study of two commonly used approaches, namely, image transformation using image-warping transforms13; before ratioing and, alternatively, image mapping on to three-dimensional model space (using resection methodology13; prior to ratioing) prior to ratioing, is attempted here. PSP results along with conventional static port data as13; on a generic aircraft model at a freestream Mach number of 0.6 and incidence of 10 deg (taken from earlier work)13; are utilized to critically assess the merit of the preceding two approaches. The analyses show that image-warping13; methods can result in larger errors in regions of strong spatial gradients of pressure and on bodies that are significantly13; three dimensional. Further, the resolution obtained from the resection approach is significantly greater (of13; the order of less than a pixel) compared to the transform methods.