Session: 01-02-01: Adaptive and Multifunctional Structures

Paper Number: 147199

147199 - Application of Composites and Additive Manufacturing to Armament Systems 

The emphasis on lightweight large caliber weapons systems has placed the focus on the use of advanced composite materials. In the past composites have been applied to direct fire cannons and electromagnetic railguns. Those efforts focused on thermoplastics and high-tension winding. Unfortunately, traditional thermoplastics cannot handle the temperatures needed for howitzer and mortar applications.

For howitzers there are traditional thermosets that can handle the use temperatures, but they cure at high temperatures, and this results in a gap forming between the tube and the gun tube. Service temperatures for a mortar tube exceed the temperature capability of most high temperature thermoset materials during rapid fire, with high bore pressures and propellant flame temperatures exacerbating the problem. The mortar baseplate couples the load directly to the ground from any firing angle and any soil resulting in a very complex loading situation. Several efforts are currently underway to deal with these applications.

Armaments, especially large caliber armaments, tend to be complicated, highly loaded, and low production rate items. The complicated geometries and low rates of production lends itself to additive manufacturing (AM). One extremely attractive benefit of AM is the ability to print at the point of need. This ability can greatly simplify the logistics train and will help units stay in the fight even when cut off from resupply. However, until recently the high material property requirements and physical size have made converting these parts to AM impractical.

One current AM effort is a 155mm muzzle brake. This brake is currently cast with long lead times and a significant portion require rework. The part is roughly 33 inches long, 15 inches tall and 20 inches wide. Attempts have been made to manufacture this brake via Electron Beam Additive Manufacturing and Wire Arc Additive Manufacturing. Additionally, an effort is underway to optimize the design and print it using laser powder bed fusion.

Another effort is focused on evaluating bound metal printing as possible means of fabricating at the point of need. A program is underway to compare bound metal solutions from MarkForged, BASF, Rapida and others. The program will consist of printing coupons and conducting material property testing to compare these different materials / systems. Parts will then be fabricated, and field tested.

This presentation will go over these and other efforts currently underway at the DEVCOM Armaments Center along with their goals, progress, and future plans.

Presenting Author: Andrew Littlefield US Army DEVCOM AC Benet Labs

Presenting Author Biography: Dr. Littlefield is the lead composite engineer at CCDC AC Benét Laboratories, Watervliet, NY, where he works on composite gun tubes and shrouds, electromagnetic railgun launchers, gun barrel vibration absorbers, and simulated proof testing of mortar base plates. Prior to joining CCDC AC, he worked for the U.S. Air Force Research Laboratory on applying composites to spacecraft structures. He received the 2010 Army Science Conference Best Paper Lethality Award and several research and development awards. He has authored several journal and conference papers and technical reports. He has patents for a self-powering prognostic gun tag, an electromagnetic gun launcher, and composite mortar base plate and tube. Dr. Littlefield holds a Ph.D. in mechanical engineering from Rensselaer Polytechnic Institute (RPI).