Background:

Target:

Projectile:

Warhead design engineers and material scientists require mechanical property information under high deformation rates of loading on a wide variety of materials that have military significance.  Over the past decade, a new class of materials has begun to receive attention because it affects the performance of most all warhead designs. This new class is called “particulate materials” and includes a diverse collection of materials such as sand, explosive grains and potting materials.  One technique used to probe the behavior of such materials is to fill a large “box” with sand and fire a hemispherical-nosed projectile into it.  During such events, the projectile disturbs and crushes the sand.  It has been noted that the disturbed/crushed state of the sand correlates with the conditions that affected it.

Fractured Sand:

Need:There is no good technique for extracting sand samples making so many measurements not very definitive or useful. The Damage Mechanisms Branch has a requirement to develop a new technique for extracting sand samples from the target.

Eglin AFRL Test Results :

The figure to the right shows the target used for sampling. Nearly all of the sand has been excavated to reveal the projectile shot line. Once revealed, researchers take samples along the length of the target. The images below show the partial fractures of the sand particles under a SEI microscope.

Position vs. Time Velocity/Acceleration vs. time

High Speed Impact Sand and Target Sampling Apparatus

a.) Chain and Actuators b.) Vacuum

Florida A&M University Florida State University

Materials and Methods:

Ruben DeSousa, Richard Klimas, Daniel Mortensen, Gina TeofilakSponsor: Dr. William Cooper, Eglin Air Force Research Laboratory

Advisor: Dr. Ongi EnglanderSpecial Thanks: Dynatech Associates, Dr. Jonathan Clark, Dr. Carl Moore

For More Information Visit: http://www.eng.fsu.edu/ME_senior_design/2009/team4/

A mechanism was idealized and conceived from the ground up to include a functional system that would not only remove sand quickly, but more accurately than previous methods. The system, as seen above, consists of a chain and sprocket pulley design. Corrosion resistant steel roller chain(#35, Single Strand, 3/8" Pitch, .200" Dia.) draws the apparatus along the length of the target. A frame has been fashioned to fit securely into the target. Removal of sand is done by a dual ended vacuum as seen in figure b. This design extracts sand from one end, bypasses the motor and ejects the material into any container.

Results:While the original goal was for the system to be fully automated, time constraints allowed for toggle switch automation of the system. With the inclusion of an aluminum frame, the mechanisms movement is smooth and effective.