Design

The Energy Absorbing Material (EAM) that we chose was an aluminum honeycomb material shown in Figure 1. This material met all of the requirements and was easy to integrate into our design. The main reason for choosing this material because the material can only absorb energy effectively in one direction. If the load is not applied directly on top of the honeycomb, then the material will fail and absorb a small amount of energy. This worked with our design because the door needs to perpendicular to the wind when the door is open.

After selecting our EAM we created a design that would integrate the material. For the Aluminum Honeycomb we created a two piece housing that would crush the material when an axial wind load was applied. This box only moves in one direction to maximize the amount of energy absorbed by the honeycomb. The actual door section was created from 6061-T4 Aluminum so that material continuity was kept between the missile skin and the outer part of our door. The hinge system is all made out of 304 Stainless steel because it is the lightest material that can support the forces on the door. The final design is shown in the final design photo album.

Final Design

In order to know what loads that would be encountered in range of velocity's experienced by the missile. Using the SolidWorks© Flow Simulation to iterate for the normal axial wind load exerted on the drag panel. By iterating over for select values in the velocity range. Then gathering the data from the wind load at each velocity then interpolating for all other values. This data was then used to predict our footprint and for FEA testing of the doors opening components. The following images show the CFD particle study in shown in the final design photo album, showing the flow streams. shown in the final design photo album is an image of a surface pressure plot at one velocity iteration that was used in interpolating.

Computational Fluid Dynamics, Using Solidworks Flow Simulation

After we decided on a final design we performed FEA on the door to make sure that the door deformed as we excepted it to. In shown in the final design photo album, we used SolidWorks© to show us what the Von Mises stresses were across the door and on all the hinges. This was to check them against the yield strength with our factor of safety between 1.15 and 1.5 and to be sure they will not fail. The deformations in all parts were also obtained from the FEA calculations. These deformations were then checked to make sure a reasonable value was being obtained from the FEA. This analysis ensures that the door will perform properly and will not fail when deployed.

Finite Element Analysis

To calculate the flight path and footprint of the missile, we wrote a MATLAB© code that gave us a total distance traveled as well as a graphical image of the flight path. By inputting the initial altitude and velocity, equations were derived to be able to vary the density of the air as the missile descended towards the ground. The density would then continually change the drag force on our door, effecting the flight path of the missile. Figure 6 shows a graph of the distance traveled for different velocities with a starting height of 30,000 ft.

Calculatied Footprint