D. Varas

Numerical Analysis of the Hydrodynamic Ram Phenomenon in Aircraft Fuel Tanks

Hydrodynamic Ram (HRAM) is a phenomenon that occurs when a high-energetic object penetrates a fluid-filled container. The projectile transfers its momentum and kinetic energy through the fluid to the surrounding structure increasing the risk of catastrophic failure and an excessive structural damage on adjacent components. It is of particular concern in the design of wing fuel tanks for aircraft because it has been identified as one of the important factors in aircraft vulnerability. In order to study the aforementioned phenomenon, water filled aluminium tubes (to different volume percentages) were subjected to impact of spherical projectiles. This work is focused on the analysis of energies, momenta and pressure contours obtained by means of a previously developed and validated numerical model in order to achieve a better understanding of the fluid/structure interaction problem that takes place during the HRAM phenomenon.

Analysis of high-speed impact problems in the aircraft industry

The high cost of the energy needed to propel aircraft and ground vehicles has meant that reducing the weight in these systems is vital in order to reduce operational costs. This factor has a significant influence on the design of structures in the aeronautical industry and more recently in others such as high-speed rail networks and road haulage. This is a particularly sensitive issue for the civil aviation industry, given that the cost of fuel is one of the main expenses incurred by passenger airlines. Bearing in mind that fuel represents up to 40% of the total weight of an aircraft, a reduction of its weight results in a concurrent reduction in the amount of fuel needed as well as a significant reduction of the gross weight taken into account.

Numerical Study of the Effects of Metallic Plates in the Attenuation of the HRAM Phenomenon

Hydrodynamic Ram (HRAM) is a phenomenon that occurs when a high-energy object penetrates a fluid-filled container. The projectile transfers its momentum and kinetic energy through the fluid to the surrounding structure increasing the risk of catastrophic failure and excessive structural damage. In this work a numerical study of the influence of metallic plates, inside a fluid-filled aluminium tube, in the attenuation of the HRAM phenomenon effects is performed. The numerical results regarding walls displacement and pressure inside the tank will be compared with a case in which there are no barriers inside the tube. The simulations are performed with the software LS-DYNA applying the ALE technique.

Simulations of High Velocity Impacts of Ice on Carbon/Epoxy Composite Laminates

In this work simulations of high velocity impacts of ice spheres on carbon/epoxy laminates are accomplished. The Drucker-Prager model has been chosen to describe the mechanical behavior of the ice under high velocity impact conditions. Results have been validated by means of experimental tests performed in a wide range of impact velocities. The delaminated area was chosen as comparison variable, and reflects that the model predicts adequately the impact process.