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SPLIT-DISK TENSILE
TEST FIXTURE (ASTM D 2290)
ASTM Standard D 2290 (Reference 1) formerly included three procedures for testing ring specimens. The old Procedure B and C specimens, extruded and molded unreinforced plastic specimens and larger diameter extruded plastic pipe, respectively, utilized fixtures of the general type shown at the right side of the above photograph. The fixture for testing Procedure A specimens, i.e., parallel-fiber-reinforced ring specimens, shown at the left side of the photograph, was deleted from the standard in 2000, after responsibility for maintaining the standard was transferred from Committee D-30 Composites to Committee F-17 Plastic Piping. However, this now deleted Procedure A is still used for testing filament-wound composite rings, and the fixture is available from Wyoming Test Fixtures, Inc. Although this test method was an ASTM standard from 1964 to 2000, its popularity has varied over the years. One criticism is that some bending is induced in the ring specimen at the split. This is even reflected in the title of the standard, “Apparent Hoop Tensile Strength …”. This is analyzed and discussed in detail in References 2 and 3. Friction between the split disk fixture and the ring specimen is also a concern. These effects are discussed in References 3 and 4. In general, this is still generally considered an acceptable test of composite rings. These former Procedure A specimens are hoop-wound rings of controlled diameter, width, and thickness, viz., 5.750" inside diameter, 0.250" wide, and 0.060" thick, to fit the standard test fixture. The revised ASTM D 2290 standard still designates Procedures A, B, and C. Procedure A is used for testing reinforced-thermosetting resin pipe, Procedure B for thermoplastic pipe of any size, and Procedure C for thermoplastic pipe with nominal diameters of 4.5” and greater. All of these revised procedures use the same fixture configuration (that shown on the right side of the above photograph), the fixture size varying to accommodate the particular specimen size of interest. Within limits, specimens of varying sizes can be tested using the same holders, by using interchangeable pairs of split disks. These various specimen configurations and test procedures are fully defined in the 2000 version of ASTM D 2290 (Reference 1). Details of the fixture and specimen for testing filament-wound rings can be found can be found in earlier versions of the same standard. Sources of Additional Information: 1) 1) ASTM Standard D 2290-00, "Apparent Tensile Strength of Ring or Tubular Plastics and Reinforced Plastics by Split Disk Method," American Society for Testing and Materials, West Conshohocken, Pennsylvania (first issued in 1964). 2) 2) C.E. Knight, Jr., "Failure Analysis of the Split-D Test Method," Composite Materials: Testing and Design (4th Conference), ASTM STP 617, American Society for Testing and Materials, West Conshohocken, Pennsylvania, 1977, pp. 201-214. 3) 3) S.H. Yoon, W.M. Cho, and C.G. Kim, “Measurement of Modulus in Filament Wound Ring Specimen Using Split Disk Test,” Experimental Mechanics, January/February 1997, pp. 25-28. 4) 4) I.A. Jones, V. Middleton, and M.J. Owen, “Roller-Assisted Variant of the Split Disc Test for Filament-Wound Composites,” Composites, Part A, Vol. 27A, 1996, pp. 287-294.
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