![]() Passive elastomeric isolators are preferred over active ones, due to their simplicity, tailorability and ease of fabrication. In a launch vehicle, vibration isolators are used to protect sensitive electronic equipments from the rigors of structural vibrations during the lift-off and ascent phase. This is an open access article under the CC BY-NC-ND license ().Ĭontents lists available at ScienceDirectĬase Studies in Engineering Failure Analysis Finally, it was concluded that micro cracks formed during the deep drawing operation (due to large strains at the fore end corner) propagated during vibration testing resulting in the failure of the body of the vibration isolator. Detailed optical and scanning electron microscopy was conducted on the failed vibration isolator to understand the reasons for cracking. The vibration isolator had a crack of length approximately 42 mm at the fore end corner. Failure of one such vibration isolator made of AISI 304 is reported in the present study after ground level testing has been completed. Vibration isolators are used in launch vehicles to protect sensitive electronic equipments from the rigors of flight structural vibrations during the lift-off and ascent phase. Material Characterization Division, Materials and Metallurgy Group, Vikram Sarabhai Space Centre, Trivandrum 695 022, India A high-repetition-rate laser has been procured and will be used more » to verify these signal and noise scaling relationships at high repetition rates.CASE STUDIES IN ENGINEERING FAILURE ANALYSISįailure analysis of a vibration isolator used in launch vehicle applications A compact, rugged, RF-excited waveguide laser can produce 15 nanosecond pulses at a 100 kHz rate with sufficient energy per pulse to reach the speckle limit of the signal-to-noise ratio. Atmospheric effects can be minimized, albedo can be rapidly scanned, and uncorrelated speckle can be acquired at the maximum possible rate. « lessĪnalysis of noise sources in Differential Absorption LIDAR (DIAL) in the infrared region of the spectrum indicates that the signal-to-noise ratio for direct detection can be improved if multiple-wavelength, short-pulse-length beams are transmitted and received at high repetition rates. In addition, detection of clouds in the mesosphere during the day appears feasible. These indicate that useful measurements of density and inferred temperature should be achievable for the mesopause region, particularly at night and during twilight. Performance simulations for the fixed bandpass operating mode are discussed. ![]() The received signal is integrated as a function of equivalent range over a bandpass that may be either fixed or scanned in the wavelength domain. The detection system consists of a dual scanning Fabry Perot Spectrometer (FPS) followed by a cooled photomultiplier operated in `photon counting` mode. The lidar is switched between transmit and receive modes by a high speed rotating shutter system. The telescope also serves as the collecting optics for the receiving system. The laser emits at a wavelength of 532 nm with an average power of 30 W. The lidar transmitter consists of a commercial injection-seeded pulsed ND:YAG laser coupled to more » a altazimuth mounted Cassegrain telescope with a 1 meter diameter primary mirror. Research utilizing the multi-instrument database will be aimed at assessing climatic variability and coupling processes throughout the atmosphere. The siting of the lidar will allow for data comparison with existing optical, radar and balloon-borne atmospheric studies. After the fiber optic switch, an acousto- optic modulator (AOM) is used to generate a pulse train used to injection seed an erbium doped fiber amplifier (EDFA) to produce eye-safe laser pulses with maximum pulse energies of 66 E) from early 1996 for the long-term measurement of atmospheric parameters as a function of altitude from the lower stratosphere to the mesopause. ![]() Two in-line fiber optic switches are used to switch between online and offline operation. The laser transmitter uses two tunable discrete mode laser diodes (DMLD) operating in the continuous wave (cw) mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. A scanning differential absorption lidar (DIAL) instrument for monitoring carbon dioxide has been developed.
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