Yuxin Sun

Theoretical analysis and multi-objective optimisation for gradient engineering material arresting system

ABSTRACT Aircrafts may overrun the runway during take-off and landing, leading to a catastrophe involving aircraft damage and even loss of life. In order to protect aircrafts and crews from casualty, a gradient engineering material arresting system (GEMAS) was developed to arrest the overrun aircrafts with different size in comparatively short distances securely. This paper presented an analytical model to predict the crushing resistance exerted on the aircraft landing gear, and the corresponding numerical model was established to validate the accuracy of the analytical results. Response surface model for design of experiment (DOE) as well as numerical simulations was employed to conduct multi-objective optimisation to seek for the optimal design parameters for GEMAS. Besides, parametric investigations were performed to discuss the effects of initial height, dipping angle and material strength on the design response (drag ratio and penetration depth) for the GEMAS according to the DOE results. Finally, multi-objective optimisation design was engaged in improving the arresting system by means of a desirability approach, aiming at obtaining the specific drag ratio and the minimum penetration simultaneously.

Fluid–structure interaction analysis of the drop impact test for helicopter fuel tank

Abstract The crashworthiness of helicopter fuel tank is vital to the survivability of the passengers and structures. In order to understand and improve the crashworthiness of the soft fuel tank of helicopter during the crash, this paper investigated the dynamic behavior of the nylon woven fabric composite fuel tank striking on the ground. A fluid–structure interaction finite element model of the fuel tank based on the arbitrary Lagrangian–Eulerian method was constructed to elucidate the dynamic failure behavior. The drop impact tests were conducted to validate the accuracy of the numerical simulation. Good agreement was achieved between the experimental and numerical results of the impact force with the ground. The influences of the impact velocity, the impact angle, the thickness of the fuel tank wall and the volume fraction of water on the dynamic responses of the dropped fuel tank were studied. The results indicated that the corner of the fuel tank is the most vulnerable location during the impact with ground.

An Exact Analytical Solution for Thermoelastic Response of Clamped Beams Subjected to a Movable Laser Pulse

The thermoelastic dynamic response of a clamped Bernoulli beam was studied when it was irradiated by a movable, temporally non-Gaussian, laser pulse. Both the energy absorption depth and the time decaying effects were considered. The temperature distribution, deflection, vibration acceleration, and stress of the beam were derived analytically, and the variations of them with time and space were illustrated. It was shown that the vibration frequency is independent of the scanning speed of the laser pulse. It is important to notice that, although the deflection of the beam is small, high vibration acceleration can be induced in microbeams, which is important for failure and fracture of the beam. Moreover, compressive stress is induced in the beam, but the importance of temperature-induced stress and deformation-induced stress may be different according to the duration time and moving speed of the laser pulse.