Advanced Materials and Manufacturing,
ASA(ALT),
Phase I

Impact Resistant Baseplate

Release Date: 03/30/2021
Open Date: 04/14/2021
Application Due Date: 05/18/2021
Close Date: 05/18/2021
Solicitation: 21.4
Topic Number: A214-006
Duration: 6 months
Amount Up To: $256K

Objective

Develop a lightweight cost-effective design for a mortar weapon system baseplate (i.e. of a composite material or structure) that handles high impact loading while in contact with soil.

Description

Many different systems, cranes, construction equipment, howitzers, etc., use some form of plate structure to couple loads to ground. These structures often consist of a flat plate with spades on the bottom to interface with the ground. The plate is normally connected to the main structure via a strut and ball-and-socket joint allowing for the plate to adjust to uneven ground. This arrangement means that the load can go through the plate at various angles. The plate also needs to interact with various soil conditions in addition to loads coming from different angles and directions. This tends to result in very heavy and robust metallic structures, which can be a severe detriment to any systems that need to be relocated by hand. For current applications the production versions of these plates are made of cast aluminum or a steel weldment.

The Army is looking for lightweight baseplate design that is resistant to the impulse load of the mortar round (which can be up to 500 kips of force) and can be made to conform to the plate with spades design. The material and associated fabrication method should also be low cost such that the final baseplates are in the same price range as current metal ones (no more than $3000.00 for an M3A2 81mm baseplate and $16,600.00 for a M9A1 120mm baseplate). The system should have a fatigue life at least as good as its metallic counterpart (which means it functions correctly for 3,000 firing cycles). The final space claim of the new ground interface plate should also be roughly the same as the old one. The system weight should be less than the current systems, ideally under 20 lbs for an 81mm baseplate and under 100 lbs for a 120mm baseplate.

Phase I

Develop and demonstrate a system that is resistant to impact loading. Provide the conceptual design or model of a ground interface plate that utilizes this material. Demonstrate that the material is an improvement over the standard carbon fiber and epoxy materials (e.g. IM7, Endurance 4505A resin w/ 4506B hardener). The ground interface plate design should be able to handle an impact load of 130 kips at a 45 degree angle from the top of the plate. The plate should fit within a 2 ft diameter by 6 inch tall envelope. The deliverable for this phase will be a report detailing the new design. If a new material is proposed a 1 pound sample of the proposed material will also be required.

Phase II

Refine the material system and produce the selected design using a process representative of plant-scale production manufacturing. Use the material to fabricate a full-size baseplate and demonstrate that it can survive the impulse load. Calculate fatigue life of the baseplate and show that it exceeds 3000 cycles. Generate a design, including fatigue life, for a second ground interface plate that can survive a 500 kip impulse and fits within a 3 ft diameter by 12 inch tall envelope. The material deliverable shall be 10 kg of the developed material and the proposed smaller ground interface plate.

Phase III

Finalize the development of a design solution at production level quantities that can be readily implemented on existing manufacturing equipment. Non-DoD applications include deep well components, sporting goods, fixturing, etc.

Submission Information

For more information, and to submit your full proposal package, visit the DSIP Portal.

References:
  1. Tomich, A., Littlefield, A., Molligan, D., Burris, R., “3D Woven Composite Mortar Baseplate,” SAMPE 2014, 3 – 5 Jun 2014, Seattle, WA.
  2. Littlefield, A, and Sibilia, J,” Simulated Proof Testing of Mortar Baseplates,” Proceedings of 26th Army Science Conference, 1 – 4 Dec 2008, Orlando, FL.
  3. Root, J., O’Hara, P. and Littlefield, A.,, “Modular Mortar Baseplate,” US Patent Number: 8707849 (29 Apr 2014)
  4. Soheillian, R., Stewart, C., Mone, R., Gurijala, A., “Enhancing the Through Thickness Modulus of Carbon Fiber Composites using Z-Axis Oriented Milled Carbon Fiber,” Boston Materials, 10 Dec 2020. https://bostonmaterials.co/wp-content/uploads/2020/12/201211-Enhancing-Through-Thickness-Modulus-of-CF-Composites.pdf
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  6. Soheilian, R., and Gurijala, A., “Systems and Methods for Forming Short-Fiber Films, Comprising Thermosets, and Other Composites,” US Patent Application No. 16/495,890, 9 Jul 2020.
  7. Mencattelli, L., Pinho, S., “Realising bio-inspired impact damage-tolerant thin-ply CFRP Bouligand structures via promoting diffused sub-critical helicoidal damage,” Composites Science and Technology, Volume 182, 2019, https://doi.org/10.1016/j.compscitech.2019.107684.
  8. Rivera, J., Yaraghi, N., Huang, W., Gray, D., Kisailus, D., “Modulation of impact energy dissipation in biomimetic helicoidal composites,” Journal of Materials Research and Technology, Volume 9, Issue 6, 2020, Pages 14619-14629, https://doi.org/10.1016/j.jmrt.2020.10.051.
  9. Suksangpanya, N., Yaraghi, N., Kisailus, D., Zavattieri, P., “Twisting cracks in Bouligand structures,” Journal of the Mechanical Behavior of Biomedical Materials, Volume 76, 2017, Pages 38-57, https://doi.org/10.1016/j.jmbbm.2017.06.010.
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