Bird Strike - Project - 2

Bird strike analysis of simplified model using LS-DYNA

Introduction:

In this project, we have performed the bird strike analysis using Lagrange formulation. The bird is simplified in this case because shell element is used and material used for bird is elastic material. Except that everything is kept quite similar to actual bird strike simulation.

Keyword used:

These are the keywords used in this case. The boundary set SPC is created for bird to move in translational x directions only and for blade to rotate in rotational x-directional only. The contact is made between the turbine blade and bird and blade itself and blade with case. The control card is created with termination time of 5 ms with time-step of 0.01 ms. Solution card is created to perform structural analysis only. The output is controlled using the database card and requested the output for glstat and matsum. The binary d3plot is for the animation. The curve is used to define the material behavior of material (aluminum). There are 7 include files made for each of the parts, control cards and materials. For velocity, velocity generation keyword is used for bird and blade both. The velocity for blade is taken as -0.26 rad/ms and for bird it is 150 mm/ms. The mat keyword possess three types of material and elastic is used for the bird, piecewise linear plasticity is use for the blade and add erosion is used for defining the failure criteria for the bird.

Analysis:

Energy:

From above graph, we can say that the energy is almost conserve. Energy ratio is almost equal to 1. This gives us evidence of good simulation. The rise and fall of the kinetic and internal energy is opposite which is required. Thus, we can proceed ahead with this model.

Erosion of the blade:

The erosion of the fan has occurred in a expected way. As the velocity of the bird is very high and is made of elastic material, it does not deform and erode but fan blade does because it is non-linear material. Thus, bird passes without damaging most of the blade.

Kinetic energy of bird:

The bird kinetic energy has reduced at very great extent within a very short duration and then after remained constant.

Internal energy of blade:

The internal energy of the blade is increasing correspondingly oppose to the decreasing kinetic energy of the bird.

Learning outcomes:

• how to perform bird strike simulation
• how to define initial_velocity_generation for rotational velocity
• how to create include files

Conclusion:

Ls-dyna provide us extensive exhaustive card to perform analysis for different kind of real world simulation. The bird strike simulation can be done using the simplified model for practice.