Engineering topics

Nagarajan, S.

Publications and source records attributed to Nagarajan, S..

3 records

NASA NTRS1992

Infrared thermographic analysis of polymer composites during ballistic impact

An infrared thermographic system was used to measure the surface temperature profile of composite materials under ballistic impact. The heat deposited was calculated based on the temperature profiles. The extent of damage induced in the materials was determined qualitatively from the measured data. The relative contribution of frictional heat to total energy absorption was evaluated, and the effect of the shape of the projectile on the extent of damage and temperature distribution in the composites was examined. The results show that graphite and polyethylene composite are more effective than Kevlar composite in dissipating heat during the ballistic impact penetration process due to their higher thermal conductivity.

Hsieh, C. Y.↗

NASA NTRS1992

Erbium-doped fiber amplifier elements for structural analysis sensors

The use of erbium-doped fiber amplifiers (EDFA's) in optical fiber sensor systems for structural analysis is described. EDFA's were developed for primary applications as periodic regenerator amplifiers in long-distance fiber-based communication systems. Their in-line amplification performance also makes them attractive for optical fiber sensor systems which require long effective lengths or the synthesis of special length-dependent signal processing functions. Sensor geometries incorporating EDFA's in recirculating and multiple loop sensors are discussed. Noise and polarization birefringence are also considered, and the experimental development of system components is discussed.

Hanna-Hawver, P.↗

NASA NTRS1967

Growth of turbulent magnetic fields.

Weak random initial magnetic field evolution in highly conducting isotropically turbulent fluid, noting exact initial growth expression of magnetic energy spectrum

ENERGY SPECTRUM↗