Abstract
A method is presented for obtaining good images of a sprayed speckle pattern on specimen surfaces at high temperatures, suitable for strain measurement, by digital image correlation (DIC) using plasma spray for speckle preparation in which a bandpass filter, neutral density filters, and a linear polarizing filter are used to reduce intensity and noise in images. This is accomplished by speckle preparation through the use of plasma spray and suppression of black-body radiation through the use of filters. By using plasma spray for speckle preparation and the filters for image acquisition, the method was demonstrated to be capable of providing accurate DIC measurements up to 2600°C. The full-field stretching deformation of the specimen was determined using the DIC technique. Experimental results indicate that the proposed high-temperature DIC method is easy to implement and can be applied to practical, full-field, high-temperature deformation measurements with high accuracy.
Highlights
Carbon fibers represent a large portion of the materials used in aeronautics and aerospace structures, and in the reinforcement of composites
Based on the speckle pattern prepared by the sprayed tungsten powder and the images of deformation acquired by using filters, this paper proposes an experimental approach for measuring the thermo-mechanical properties of carbon fibers at temperatures up to 2600°C
The specimen was heated to 2600°C by electric current at first, and the specimen was stretched until fracturing in a 2600°C environment
Summary
Carbon fibers represent a large portion of the materials used in aeronautics and aerospace structures, and in the reinforcement of composites. They display a very wide range of thermal, electrical, and mechanical properties: elastic moduli vary between 30 and 900 GPa, and strength can be as high as 6 GPa.[1] Not many research studies have been performed on the properties of the fibers and matrices of carbon at high temperatures.[2,3] In recent years, the thermo-mechanical response of carbon fibers has become an area of great interest among researchers. A validation study of the thermal expansion and the tensile Young’s modulus of carbon steel 1020 at temperatures up to 850°C was measured through using specially designed, high-temperature specimen grips by Codrington et al.[5]
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