Issue 24

A. V. Babushkin et alii, Frattura ed Integrità Strutturale, 24 (2013) 89-95; DOI: 10.3221/IGF-ESIS.24.09 89 Special Issue: Russian Fracture Mechanics School Research of the effectiveness of mechanical testing methods with analysis of features of destructions and temperature effects A.V. Babushkin, D.S. Lobanov, A.V. Kozlova, I.D. Morev Perm National Research Polytechnic University, 614990, Komsomolsky av., 29, Perm, Russia bav651@yandex.ru A BSTRACT . In this paper is carried out the comparative analysis of effectiveness of test methods of determination of stiffness and strength properties of highly filled unidirectional fiberglass (Direct "E" roving 0.7 - orthophthalic polyester resin 0.3) via tensile testing along the reinforcement and three-point bending testing at several bases. The necessity of deviation from standard procedures is substantiated. Deformation and failure features of the material under quasi-static loading, as well as at low and high temperatures, are shown. K EYWORDS . Composite materials; Highly filled fiberglass; Test methods; Deformation and failure; High and low temperature. I NTRODUCTION or designing and providing reliable operation of high loaded shell structures from layered-fiber cross-reinforced composites are relevant issues of an adequate definition of effective elastic and strength properties of the material. These issues are usually resolved with help of mathematical modeling or tests. In this case, the structural- phenomenological modeling should be also based on the test determination of properties and features of the mechanical behavior of structural components of the composite. For modeling of a cross-reinforced fiberglass are most relevant properties of texture layer - that is a unidirectional fiber composite. Determination of unidirectional fiber composite properties is usually based on ASTM D 3039. In the test research of composite materials in the product is convenient to use method of beam-specimens bending on different bases, as this method allows determine the longitudinal strength and elastic modulus, shear modulus and shear (interlayer) strength [1]. According to this method, the properties are determined by three-point bending testing on different bases of beam-specimens, which are cut in the appropriate direction of finished product. This approach allows take into account technological features of the material production into product. However, this method gives obviously lower results, as work conditions of relatively short reinforcing fibers in cut specimen and continuous fibers in the product are significantly different. Anyway, in both cases, the result is based on test data. In practice, the lower results at test are interpreted as a certain margin of safety in product designing. Naturally, questions of estimation of this stock value and the adequacy of various test methods for providing structural mathematical modeling on the one hand, and product design in the framework of phenomenological approaches - on the other, arise. In this paper is held a comparative analysis of different methods of test determination of unidirectional fiberglass stiffness and strength properties, deformation and fracture characteristics of these materials under quasi-static loading and also at low and high temperatures. F