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.

Prediction of Fatigue Crack Growth After Single Overload in an Aluminum Alloy

Abstract: An analytical method using crack driving force parameter ∆K ∗ was developed to account for the single overload interaction effects on the constant amplitude fatigue crack growth behavior in D16 (2024-T3 equivalent) aluminum alloy. Crack growth acceleration and retardation were accounted for by using residual stress intensity concept. Fatigue crack growth behavior was predicted using this method for a thin SE(T) specimen subjected to 1) constant amplitude load and 2) constant amplitude load interspersed with single tensile overloads at certain intervals of crack length. Fatigue crack growth tests were performed with these load sequences, and the experimental crack growth results obtained were compared with predictions made by use of the proposed analytical method. All of the fatigue crack growth tests were performed in a servohydraulic test machine. Crack length was measured by the traveling microscope/cellulose acetate replication method. A fairly good correlation was obtained between the experimental and predicted fatigue crack growth curves under the applied loading sequence.

Mixed mode cohesive zone modelling and analysis of adhesively bonded composite T-joint under pull-out load

Abstract: The failure behaviour of three different configurations of adhesively bonded carbon fibre composite T-joints subjected to pull-out load is investigated. Finite element analysis is carried out on the carbon fibre composite T-joint models. A non-linear, contact target-based cohesive zone model with appropriate traction separation law is selected to simulate the pull-out test condition in FE package ANSYS®. The FE analysis results are in close agreement with available experimental results.

Psychophysical thresholds associated with the simulation of linear acceleration

Abstract: This paper presents the range of motion stimuli that produce realistic sensations of longitudinal acceleration during a simulated take-off run in an advanced research simulator. The gain of the translational (surge) and tilt-coordination channel (pitch) were systematically varied, together with the bandwidth of the high-pass filter of the surge channel. Seven experienced pilots judged their motion perception. Based on their subjective response, psychometric curves were constructed in order to determine the minimum and maximum permissible gain settings of the washout algorithm. The results suggest that platform motion was generally overestimated relative to the visually simulated motion. It is therefore concluded that for realistic perception of linear accelerations in a flight simulator, downscaling is essential. The best simulation was obtained with a gain of 0.2 (in combination with a bandwidth of 0.73 rad/s) for the high-pass filter in the translational channel and a gain of 0.6 for the low-pass filter in the tilt-coordination channel.