Comparative Analysis of Aerodynamic Characteristics of F16 and F22 Combat Aircraft using Computational Fluid Dynamics

This paper presents the computational investigation of air flow over an aircraft at realistic speeds while demonstrating the importance of extending the existing analysis to the complete airplane and how pivotal it is in improving its in-flight performance. The study is done for F16 and F22 aircraft using ANSYS Fluent (19.2) to obtain pressure distribution, shear stress distribution and temperature variation on the complete surface of the aircraft. Since the front section of the aircraft is prone to direct initial impact of surrounding environment, this portion is also examined. Here, as the speed is doubled from Mach 1 to Mach 2, a rise in the value of all the three variables is noticed for the F16 aircraft, whereas the pressure distribution for F22 aircraft shows strange behaviour for the highest speed (Mach 2). On comparing the results over the whole surface, it is seen that F16 experiences smaller pressure (29% lower for Mach 1 and 30% for Mach 2), temperature (9.5% lower for Mach 1 and 30% for Mach 2) and shear stress relative to F22 and the stress shows a huge change (90% lower for Mach 1 and 83% for Mach 2). Results of the present study imply that the design of the aircraft highly influences its performance as the parameters discussed touch their limits

Influence of micro-structural parameters on fatigue life of discontinuous reinforced metal matrix composites

348-355The micro-structural parameters such as reinforcement shape, size, distribution, volume fraction, property mismatch, aging condition, bonding strength, and whisker orientation can influence the fatigue life of discontinuous reinforced metal matrix composites (DRMMCs). The strengthening effect plays a vital role in predicting the fatigue behaviour of DRMMCs. The modified shear lag (MSL) and enhance dislocation density (EDD) are two main factors that describes the strength of DRMMCs. In the present work, fatigue crack growth life model based MSL and EDD strengthening mechanism has been developed by integrating fatigue damage deformation at the crack-tip under the total strain-controlled conditions. The closed form expression predicts the dependency of particle size, reinforcement volume fraction and reinforcement constraint of the matrix on the fatigue crack growth life. The model fitting with experimental data affirms the appropriateness of proposed fatigue crack growth life prediction model for DRMMCs

Influence of micro-structural parameters on fatigue life of discontinuous reinforced metal matrix composites

The micro-structural parameters such as reinforcement shape, size, distribution, volume fraction, property mismatch, aging condition, bonding strength, and whisker orientation can influence the fatigue life of discontinuous reinforced metal matrix composites (DRMMCs). The strengthening effect plays a vital role in predicting the fatigue behaviour of DRMMCs. The modified shear lag (MSL) and enhance dislocation density (EDD) are two main factors that describes the strength of DRMMCs. In the present work, fatigue crack growth life model based MSL and EDD strengthening mechanism has been developed by integrating fatigue damage deformation at the crack-tip under the total strain-controlled conditions. The closed form expression predicts the dependency of particle size, reinforcement volume fraction and reinforcement constraint of the matrix on the fatigue crack growth life. The model fitting with experimental data affirms the appropriateness of proposed fatigue crack growth life prediction model for DRMMCs

Uncovering remarkable contribution of lasers peak intensity region in holography

International audienceFor the scheme of two colour lasers in interference and holography, we uncover remarkable contribution of focusing region (spread) of the peak intensity of superposing laser beams based on the numerical studies and confirm it by mathematical calculations. The pulses having peak intensity for a wider region create better interference pattern, leading to higher modulation depth. Also, such beams having a stronger intensity gradient enhance the range of frequency detuning (difference), which would ease the experimentation in getting better holograms. A comparison of the results achieved with such beams is done with the most commonly used Gaussian beams for the better understanding of the concept for the advancement in holography