Accession Number : ADA455569


Title :   High Strength and Impact Damage Tolerant Syntactic Foam for High Performance Sandwich Structures


Descriptive Note : Final rept. 1 Sep 2005-31 May 2006


Corporate Author : SOUTHERN UNIV AND A AND M COLL BATON ROUGE LA DEPT OF MECHANICAL ENGINEERING


Personal Author(s) : Li, Guoqiang


Full Text : http://www.dtic.mil/get-tr-doc/pdf?AD=ADA455569


Report Date : 25 JUL 2006


Pagination or Media Count : 44


Abstract : This study explored a novel higher strength and higher impact tolerant syntactic foam for composite sandwich structures. A unique microstructure was designed and realized through a unique manufacturing technology. The foam was fabricated by dispersing rubber latex coated microballoons into a nanoclay and milled microfiber reinforced epoxy matrix. Each component was designed to contribute to a desired property of the foam. The nanoparticle and microfiber served to increase the strength and stiffness (stronger and stiffener); the microballoon served as a light-weight filler (lighter); and the rubber coating served to increase the toughness and the impact tolerance (tougher). The manufacturing process for developing this unique microstructure was developed. Both low velocity impact test and four-point bending test were conducted on the foam core and sandwich beams. The test results showed a considerable increase in energy absorption capacity and the capacity for retaining the residual bending strength. This multi-phase material contained structures bridging over several length-scales. The SEM pictures showed that several mechanisms were activated to collaboratively absorb impact energy, including microballoon crushing, interfacial debonding, matrix cracking, rubber pinning, fiber pull-out, and fiber bridge-over. The localized and microscale damage insured that the sandwich beams retained its strength after the impact.


Descriptors :   *MICROSTRUCTURE , *COMPOSITE STRUCTURES , *HIGH STRENGTH , *LIGHTWEIGHT , *SANDWICH CONSTRUCTION , TEST AND EVALUATION , IMPACT , FOAM , EPOXY COATINGS , ENERGY ABSORBERS , TOUGHNESS , TOLERANCE , STRENGTH(MECHANICS) , IMPACT TESTS , STIFFNESS , CRACKING(FRACTURING)


Subject Categories : COATINGS, COLORANTS AND FINISHES
      PROPERTIES OF METALS AND ALLOYS
      MISCELLANEOUS MATERIALS


Distribution Statement : APPROVED FOR PUBLIC RELEASE