NATIONAL INSTITUTE OF AEROSPACE

Frank L. Palmieri

Frank L. Palmieri

Frank PalmieriTel: +1 (757) 864-8802; Fax: +1 (757) 864-8312
Email: frank.l.palmieri@nasa.gov

Research Interests

  • Surface engineering and surface characterization;
  • Structural bonding of advanced aerospace materials;
  • Mechanical testing and chemical analysis;
  • Micro- and nano-fabrication/lithography; and
  • Materials/polymer formulation, processing and characterization.

Education

  • Ph.D. (2008), Chemical Engineering, Dept. Chemical Engineering, The University of Texas at Austin, TX
  • B.S.  (2002), Chemical Engineering, School of Engineering, Virginia Commonwealth University, Richmond, VA

Current Research

  • Laser Surface Preparation of Titanium Adherends for High Temperature Adhesives:

Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Laser ablation imparts both topographical and chemical changes to a surface, which can lead to increased bond durability and repeatability. A laser-based process provides an alternative to chemical-dip, manual abrasion, and grit blast treatments, which are expensive, hazardous, polluting, and less precise. The goal of this work is the testing of a surface preparation technique based on laser ablation as a replacement for the chemical etch and abrasive processes currently applied to Ti-6Al-4V alloy adherends. Failure mode, surface roughness, and chemical makeup are analyzed using fluorescence enhanced visualization, microscopy, and X-ray photoelectron spectroscopy, respectively. Single lap shear tests were conducted on bonded and aged specimens to observe bond strength retention and failure mode. Results to date suggest that laser ablation is a viable process for inclusion with or/and replacement of one or more currently used titanium surface treatments. On-going work will focus on additional mechanical tests to further demonstrate improved bond durability.

  • Flexible, space durable microwave antenna arrays based on meta-material backplane:  

The concept included the design, fabrication, and testing of conformal patch antennas that incorporate artificial magnetic conductors (AMC’s) into the substrate below the radiating patches.  The AMC is a meta-material which creates an electronic band gap at the operating frequency of the antenna.  This band gap prevents the propagation of parasitic surface waves along the antenna backplane.  In this fashion, the AMC substrates are expected to improve the performance of the antenna by improving both the electrical efficiency and the shape of the electric field patterns. Other aspects of the concept included a conformal patch array, a monolithic microwave integrated circuit (MMIC) feed system, and a protective dielectric layer over the top of the antenna.

  • Manufacturing methods of damage tolerant membranes for solar sail applications:

Expandable structural systems such as solar sails, solar power arrays, antennas, and numerous other large aperture devices are used in space to collect, reflect and/or transmit electromagnetic radiation.  Such structures are lightweight membranes and must package efficiently for launch; however, they must be expanded (deployed) in-orbit to achieve the desired geometry.  This work is an integrated approach to develop thin-film, damage-tolerant, membranes using advanced manufacturing.  Bio-inspired hierarchical structure is printed on films using additive manufacturing to achieve improved tear resistance and to facilitate membrane deployment.  Test results show this initial work produces higher tear resistance than neat film of equivalent mass.

  • Laser surface preparation for bonding of Carbon Fiber Reinforced Plastic (CFRP) followed by ageing adherends in hot wet environments:

Fiber reinforced resin matrix composites offer weight savings without sacrificing strength and mechanical performance.  Since service history is not well established, a long-term environmental aging study was undertaken. Direct-write UV laser (355 nm) processing was used to ablate cross-hatched patterns with a 2 mil line pitch into CFRP adherend surfaces. Adhesive bonds were prepared by secondary bonding of 3M™ Scotch-Weld™ AF-555M between pre-cured, unidirectional composite adherends comprised of Toray™ T800H/3900-2. Single lap shear specimens were fabricated and subsequently aged in an unstressed configuration at 71 °C (160 °F) and 85 % relative humidity for up to 772 days.  The lap shear strengths were measured periodically at both room temperature and 160 °F, and failure modes were determined and compared to control specimens that had been stored for equal periods of time at room temperature under low humidity. With hygrothermal aging, apparent shear strengths decreased and the failure mode progressed from cohesive (within the adhesive layer) to fiber tear (within the top plies of the adherend laminate) similar to specimens without laser ablation treatment.

  • Laser surface preparation of Carbon Fiber Reinforced Plastic (CFRP) for improved durability and crack arrestment:

Research is conducted as part of an SAA with Boeing to determine if laser surface preparation can be used to improve in CFRP composite joints. CFRP composite specimens are surface treated by laser ablation using various patterns and powers. Specimens are bonded using a tough adhesive to maximize stress the adherend/adhesive interface during testing. Boeing Rapid Adhesion Tests (B-RAT) and wedge tests are used to qualitatively select laser parameters and patterns, that demonstrate the most desirable failure modes.  Double Cantilever Beam (DCB) tests were selected based on B-RAT results to measure the propagation strain energy release rate under stable crack growth conditions.

Recent Publications

  1. Palmieri, Frank; Watson, Kent; Morales, Guillermo; Wohl, Christopher; Williams, Thomas; Hicks, Robert; Connell, John. Laser Ablation Surface Preparation of Ti-6Al-4V for Adhesive Bonding. SAMPE Conference Proceedings, May 2012, Baltimore, MD. (in press)
  2. Siddarth, Chauhan; Palmieri, Frank; Bonnecaze, Roger T.; Willson, C. Grant. Feature filling modeling for step and flash imprint lithography. J. Vac. Sci. Technol. B (2009), 27(4), 1926-1932.
  3. Siddarth, Chauhan; Palmieri, Frank; Bonnecaze, Roger T.; Willson, C. Grant. Pinning at template feature edges for step and flash imprint lithography. J. App. Phys. (2009), 106(3), 4902-4908.
  4. Heath, William H.; Palmieri, Frank; Adams, Jacob R.; Long, Brian K.; Chute, Jerred; Holcombe, Thomas W.; Zieren, Shelley; Truitt, Matthew J.; White, Jeffery L.; Willson, C. Grant. Degradable crosslinkers and strippable imaging materials for step-and-flash imprint lithography. Macromolecules (2008), 41(3), 719-726.
  5. Palmieri, Frank; Adams, Jacob; Long, Brian; Heath, William; Tsiartas, Pavlos; Willson, C. Grant. Design of reversible cross-linkers for step and flash imprint lithography imprint resists. ACS Nano
    (2007), 1(4), 307-312.
  6. Palmieri, Frank; Stewart, Michael; Jen, Kane; Wilson, C. Grant; Schmid, Gerard. Step-and-flash imprint lithography for patterning interconnect dielectrics. Solid State Technology (2007), 50(9), 42-45.
  7. Palmieri, Frank; Willson, C. G et. al. Multi-level step and flash imprint lithography for direct patterning of dielectrics. Proceedings of SPIE-The International Society for Optical Engineering (2006), 6151.
  8. Schmid, Gerard M.; Stewart, Michael D.; Wetzel, Jeffrey; Palmieri, Frank; Hao, Jianjun; Nishimura, Yukio; Jen, Kane; Kim, Eui Kyoon; Resnick, Douglas J.; Liddle, J. Alexander; Willson, C. Grant. Implementation of an imprint damascene process for interconnect fabrication. Journal of Vacuum Science and Technology, B: Microelectronics and Nanometer Structures–Processing, Measurement, and Phenomena (2006), 24(3), 1283-1291.
  9. Kim, E. K.; Stewart, M. D.; Wu, K.; Palmieri, F. L.; Dickey, M. D.; Ekerdt, J. G.; Willson, C. G. Vinyl ether formulations for step and flash imprint lithography. Journal of Vacuum Science and Technology, B: Microelectronics and Nanometer Structures–Processing, Measurement, and Phenomena (2005), 23(6), 2967-2971.
  10. MacDonald, Susan; Hughes, Greg; Stewart, Michael; Palmieri, Frank; Willson, C. Grant. Design and fabrication of highly complex topographic nanoimprint template for dual Damascene full 3-D imprinting. Proceedings of SPIE-The International Society for Optical Engineering (2005), 5992.
  11. Stewart, Michael D.; Wetzel, Jeffery T.; Schmid, Gerard M.; Palmieri, Frank; Thompson, Ecron; Kim, Eui Kyoon; Wang, David; Sotodeh, Ken; Jen, Kane; Johnson, Stephen C.; Hao, Jianjun; Dickey, Michael D.; Nishimura, Yukio; Laine, Richard M.; Resnick, Douglas J.; Willson, C. G. Direct imprinting of dielectric materials for dual damascene processing. Proceedings of SPIE-The International Society for Optical Engineering (2005), 5751.
  12. Watson, Kent A.; Palmieri, Frank L.; Connell, John W. Space environmentally stable polyimides and copolyimides derived from [2,4-Bis(3-aminophenoxy) phenyl]diphenylphosphine oxide. Macromolecules (2002), 35(13), 4968-4974.

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