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NASA COMPRESSION
AFTER IMPACT
This version of the NASA Compression After Impact (CAI) Compression Test Fixture is an alternative to the more popular Boeing Compression After Impact Compression Test Fixture, Model CU-CI or WTF-CI, described in the previous section of this catalog. Another NASA version, more closely resembling the Boeing fixture, is also available. Both NASA fixtures are described in detail in Reference 1, both utilizing a specimen 10" long and 5" wide, i.e., 4" longer and 1" wider than the Boeing specimen described in References 2 through 4. Hence, more than twice as much material is required per specimen. Thus, the NASA versions have become much less commonly used. As a result, the Boeing version has been standardized by ASTM (Reference 5), whereas the NASA version has not. The NASA fixture version shown here consists of four separate assemblies, each clamping onto an edge of the specimen as shown in the photograph. These assemblies stabilize the specimen against buckling. The lower assembly rests on the base of the testing machine, and the compressive loading is applied to the test specimen through the top assembly using a flat platen mounted in the crosshead of the testing machine. As in the Boeing method, a quasi-isotropic laminate is typically, although not necessarily, tested. Before being compression loaded to failure, the specimen is subjected to an impact loading, typically using a drop-weight impact testing device such as that defined in Reference 6. Sources of Additional Information: 1) 1) NASA Reference Publication 1092, "Standard Tests for Toughened Resin Composites," NASA-Langley Research Center, Hampton, Virginia, Revised Edition, July 1983. 2) 2) Boeing Specification Support Standard BSS 7260, "Advanced Composite Compression Tests," The Boeing Company, Seattle, Washington (originally issued February 1982, revised December 1988). 3) Boeing Document D888-10026, "Test Methods for Advanced Composites, Revision A, Section 7.4, The Boeing Company, Seattle, Washington, January 1996. 4) 4) SACMA Recommended Method SRM 2R-94, "Compression After Impact Properties of Oriented Fiber-Resin Composites," Suppliers of Advanced Composite Materials Association, Arlington, Virginia, 1994. 5) 5) ASTM Standard D7137-05 (2005), "Standard Test Method for Compression Residual Strength Properties of Damaged Polymer Matrix Composite Plates,” American Society for Testing and Materials, West Conshohocken, Pennsylvania (first issued in 2005). 6) 6) ASTM Standard D7136-05 (2005), "Standard Test Method for Measuring the Damage Resistance of a Fiber-Reinforced Polymer Matrix Composite to a Dynamic Impact Event,” American Society for Testing and Materials, West Conshohocken, Pennsylvania (first issued in 2005).
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