M. Bharath

Abstract: Researches on bio-composites are increased due to their environment friendly. Some research shows a good improvement in their mechanical property with the polymer/synthetic composites. In this paper, the damage characterization of flax epoxy composite with alumina powder as filler under acoustic emission at various stages are studied. For this work, the alumina powder with various percentages such as 3% and 5% are chosen. In this project, tensile and flexural tests are performed. From the tensile test peak load and strain functions are calculated. Acoustic emission is non-destructive technique used to find the damage mode. AE has the advantage over other method due to its high sensitivity. The three-point bending is performed on the filler infused flax/epoxy composite to evaluate the flexural damage at various percentage of filler composition. The damage characterization is studied based on the frequency obtained over the time. These failure modes such as delamination, matrix cracking fibre damage are associated with frequencies are evaluated using standard mode of damage. Duration (μs) vs. amplitude (dB) and force (N) vs. position (mm) curves are plotted to evaluate the damage. The real time various damage levels occurs during flexural loading and it was evaluated using AE techniques.

Abstract: Concrete canoe making is a prestigious multidisciplinary activity that relates the fields like concrete technology, hydrodynamics, material science, naval architecture, etc. Each year national and international level competitions are organized by various organizations. This work aimed to produce a lightweight single peddler concrete canoe. It was achieved by synergetic effects of the following activities: enhancing the floatability of hardened concrete; creating a maneuverable hull for a fresh paddler; enriching the structural performance of the canoe for the stress reversal for dealing with the curling effect in lightweight concrete and fabricating a canoe for a watertight environment.

Abstract: The working environment temperature of the landing gear shock absorber is affected by the fuselage and the airport temperature, and temperature change will affect the performance of hydraulic oil, thus affecting the damping characteristics of the shock absorber. In this paper, the thin-walled orifice is selected as the test object. Firstly, the shock absorber under different temperatures is tested with the help of the Fluid-Damping-Test-Platform. At each temperature, the shock absorber is loaded at low speed and constant speed respectively, and the variation law of oil damping force with displacement is obtained. Then, based on the dynamic mesh technology, CFD simulation of the flow field in the test shock absorber is carried out to simulate the test process and verify the reliability of the test results. Finally, the conclusion is drawn: the decrease of temperature will lead to the increase of oil viscosity, which will lead to the decrease of Reynolds number, which will lead to the decrease of discharge coefficient, and finally lead to the increase of oil damping force.

Abstract: The oleo-pneumatic shock absorber involves a complex two-phase flow in the working process. In this paper, a simple oleo-pneumatic shock absorber model was established, and the volume-of-fluid (VOF) two-phase flow model was adopted to accurately simulate the distribution of the two-phase flow field in the shock absorber through the commercial software FLUENT 2020 R2. The accuracy of the simulation model was verified by the method of engineering damping force estimation, and the error of the numerical simulation results compared with the engineering estimation results was 7–8%. By numerical simulation, the influence of different orifice lengths and diameters on the maximum pressure, temperature, velocity and oil damping force inside the shock absorber was studied. The results showed that with the increase of the orifice length, the maximum pressure, flow rate and oil damping force in the shock absorber decreased. The temperature decreased first and then increased, but the overall effect was small. However, according to the oil volume fraction contour, the gas–liquid distribution in the shock absorber with an orifice larger than 15 mm was more chaotic. Increasing the diameter of the orifice had a great impact on the shock absorber. The maximum pressure, flow rate and damping force of the oil inside the shock absorber were sharply reduced, and the temperature continued to rise. These research results can provide reference for the optimization design of oleo-pneumatic shock absorbers.