New test method to determine the constituent contents of polymeric composites. (News Briefs).Researchers at NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. are proposing a modification of the standard burn-off test to characterize carbon/glass hybrid composites, ASTM ASTM abbr. American Society for Testing and Materials D3171-99. Hybrid composites are increasingly being used in infrastructure, aerospace, and automotive applications. These hybrids use two different fibers to reinforce the resin resin, any of a class of amorphous solids or semisolids. Resins are found in nature and are chiefly of vegetable origin. They are typically light yellow to dark brown in color; tasteless; odorless or faintly aromatic; translucent or transparent; brittle, fracturing , thereby gaining some of the advantageous properties of both fibers. Typically, carbon and glass are used since this combination provides high performance and low cost. Critical issues in such materials are the fiber mix ratio and the fiber and void contents. At present, there is no simple way to determine these features, although many techniques exist for measuring the components of single reinforcement reinforcement /re·in·force·ment/ (-in-fors´ment) in behavioral science, the presentation of a stimulus following a response that increases the frequency of subsequent responses, whether positive to desirable events, or composites. The proposed amendment calls for heating the specimen in a muffle furnace furnace, enclosed space for the burning of fuel. There are many kinds of furnaces, the type depending upon the fuel and the use to which the heat produced within it is put. Most familiar are the furnaces used in the heating of buildings. in a series of steps designed to sequentially separate out the resin, carbon fibers, and glass fibers. In addition, void contents of these composites can also be calculated. Results obtained with the proposed method on both commercial and laboratory-prepared samples were found to be in excellent agreement with values obtained by labor-intensive microscopic microscopic /mi·cro·scop·ic/ (mi?kro-skop´ik) 1. of extremely small size; visible only by the aid of the microscope. 2. pertaining or relating to a microscope or to microscopy. examinations. Knowledge of the constituents in hybrid composites is needed for the development of models that accurately predict composite strength and failure behavior. The ultimate goal of this work is to use parameters such as those determined by this new test to establish a mathematical link between micromechanics properties that initiate and control the modes of composite failure and the physics of composite failure behavior. CONTACT: Walter McDonough, (301) 975-3661; walter.mcdonough@nist.gov. |
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