Continued advancements in the design and manufacture of engineered composites has allowed composite materials to work their way into the products we use everyday. By definition, a composite material is simply any material that contains two or more constituent materials. The materials that make up a composite are chosen either to enhance or supplement the material properties of the individual materials. The typical material combination seen in today's composites is a material that performs well in tension (fiber or rebar) paired with a material that performs well in compression (epoxy, ceramic, or cement). The most common modern advanced composites are fiber-matrix composites and they can be manufactured with polymer, carbon, metal, or ceramic matrix and an extremely wide range of reinforcement fiber including, carbon, graphite, boron, aramid, and glass. In practice, most engineering materials are not used in the form they are tested. This is no different with composite materials, as a functional composite part is likely to have cutouts, holes, screws, rivets, or irregular shape. Fastener pull-through tests of composites help to address the real life application of composite materials. The basic setup of a composites fastener pull-through test has a supported composite plate, with a fastener (usually a screw or bolt) running through the middle of the plate, perpendicular to the plane of the plate. This fastener is either pulled or pushed until the fastener head passes through the composite plate, measuring the pull-through force. The most important considerations when conducting a pull through test of composite materials are: the plate should be supported such that the fastener pulls through the plate before other failure of the plate occurs and the load applied to the fastener should be directed along the axis of the fastener and perpendicular to the plane of the plate. Fastener pull through tests are especially important for evaluating the use of a composite material for structures, such as aircraft fuselages, that are subject to internal pressure loads. Test fixtures are typically designed to be used in a wide variety of test environments, which are necessary to recreate the real life application conditions of composite materials. The creation of these environments is achieved through the use of saline baths for testing composites used in marine, biological, and outdoor environments and high temperature environmental chambers for composites used in the aviation, aerospace, and automotive industries. ASTM D7332 is the standard test method for testing the fastener pull-through resistance of fiber reinforced composite materials. The purpose of ASTM D7332 is to provide a test method that can be performed consistently, ensuring materials are tested in the same manner and conditions and allowing test results validation between manufactures and customers. NASM 1312-8 is also a standard that can be modified for fastener pull-through testing of composites. Most composite materials have relatively low fastener pull-through strength, however the test machine force capacity required depends on the specific material, fastener, and specimen geometry used. The machine families below can be matched to the wide range of composite materials being tested. Contact a TestResources application engineer to determine the best machine and grip combination for your exact composite testing needs.

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