Vikram Sarabhai Space Centre

About: Vikram Sarabhai Space Centre is a facility organization based out in Thiruvananthapuram, India. It is known for research contribution in the topics: Aerosol & Ultimate tensile strength. The organization has 2092 authors who have published 3058 publications receiving 47975 citations. The organization is also known as: VSSC.

Carboxyl‐terminated poly(propylene glycol) adipate‐modified room temperature curing epoxy adhesive for elevated temperature service environment

Abstract: An investigation was carried out into the effect of modification of an epoxy resin with carboxyl-terminated poly(propylene glycol) adipate (CTPPGA) liquid rubber, on room temperature and elevated temperature adhesive joint strengths, after curing at room temperature (25°C) with tris-2,4,6-(N,N-dimethyl amino methyl) phenol hardner. CTPPGA prepared by the esterification of poly(propylene glycol) (PPG) and molar excess of adipic acid was incorporated into the epoxy resin by the prereact method. CTPPGA modification showed significant enhancement of adhesive joint strengths over the unmodified epoxy and the joint strengths were found to depend on the molecular weight of CTPPGA and its content in the epoxy resin. The elevated temperature lap shear strength measurement made for the CTPPGA-modified epoxy adhesive showed that the adhesive formulation has a temperature service capability up to 120°C. The results are discussed in terms of the data obtained from the tensile tests, DSC analysis, and SEM observations of the fractured surfaces.

Energetic neutral atom observations of magnetic anomalies on the lunar surface

Abstract: [1] SARA, the Sub-KeV Atom Analyzer, on board Chandrayaan-1 recorded the first image of a minimagnetosphere above a lunar magnetic anomaly using energetic neutral atoms (ENAs). It was shown that this magnetosphere, which is located near the Gerasimovich crater, is able to reduce the solar wind ion flux impinging onto the lunar surface by more than 50%. Following this first observation, we investigated all magnetic anomalies that are in the SARA data set. We searched for a possible correlation between the solar wind plasma parameters (dynamic pressure, magnetic field), the local magnetic field, and the reduction in the reflected hydrogen ENA flux (henceforth called shielding efficiency). Having analyzed all observations by SARA, we discovered that the Gerasimovich magnetic anomaly is topologically a very simple, large-scale magnetic structure, which is favorable for this kind of investigation. Most other magnetic anomalies on the lunar surface have more small-scale features in their magnetic field structure, which complicates the interpretation of the observed data. We find a clear correlation between the plasma parameters and the shielding efficiency for the Gerasimovich case. For the other observed anomalies only about half of the cases showed such a correlation. We therefore conclude that the solar wind ions-magnetic anomaly interaction is in general more complex than in the Gerasimovich case.

Microstructure and Properties of a High-Strength Cu-Ni-Si-Co-Zr Alloy

Abstract: A high-strength Cu-Ni-Si alloy was developed with the additions of Co and Zr. The aging curve for the alloy was generated using hardness. Electron microscopy studies were conducted to analyze the phases in the alloy. Two types of phases, one of copper matrix and the other of Ni-Si-Co-Zr intermetallic phase, could be identified using scanning electron microscopy. Transmission electron microscopy studies confirmed the presence of two types of precipitates in solution-treated and aged (STA) condition, i.e., Ni2Si and Co2Si. Mechanical properties and electrical conductivity were evaluated in solution-treated (ST) and STA conditions. Aging of the ST samples at 500 °C for 3 h has shown an increase of 72 and 15% in yield strength (YS) and electrical conductivity, respectively. This increase in YS and conductivity on aging is primarily attributed to the formation of fine Ni2Si and Co2Si precipitates.

Stress relaxation behavior of short pineapple fiber reinforced polyethylene composites

Abstract: Stress relaxation behavior of short pineapple fiber reinforced polyethylene composites in tension has been studied with special reference to the effect of fiber loading, fiber length, chemical trea...