US Army Research Laboratory Aberdeen Proving Ground United States
The absence of documented properties for damage tolerant adhesives is a limiting factor in the research and development of improved bonding for Army applications. Research efforts are ongoing to study the effects of aluminum coupon thickness, bond line thickness, surface preparation, and presence of an overflow fillet for a high strength epoxy and ductile methacylate adhesive. A unique feature of this study was the use of untrained GEMS Gains in the Education of Mathematics and Science high school and middle school students to fabricate the samples to meet the large sampling set requirements for statistical analysis. Sample fabrication was limited to approximately 75 minutes to cover both the educational and experimental laboratory aspects of the GEMS program. The GEMS students were assigned to 4 teams consisting of 12 members, with approximately a 10 minute intermission break between teams. The workflow protocol needed for successful single-lap-joint fabrication required a high degree of efficiency to accommodate the scheduling and educational bounds of the GEMS program. ARL technicians performed extensive tooling and adhesive handling development prior to the arrival of the GEMS students. This protocol development was successful as the students were able to fabricate test samples with fairly tight tolerances. Further workflow protocols were developed to facilitate post-curing of the adhesive for rigorous mechanical testing by the GEMS students within 2 days of initial fabrication. The lessons learned for experimental workflow protocols will be reported with the anticipation of expanding adhesive joint test configurations as part of the GEMS program.