Estudo do comportamento mecânico de compósitos de matriz polimérica com fibra de vidro contendo descontinuidades geométricas.

Abstract

With technological advancement the properties required of conventional materials have changed leading to the appearance of materials capable of meeting the desired requirements of new technologies. One is composite materials, which have a wide application in various sectors. On the other hand, the performance of the composite is strongly dependent on the matrix-fiber interface and hence the distribution and orientation of fibers. The Fracture Mechanics is the field of mechanics that uses analytical and experimental methods to describe the behavior of solids and structures with geometrical discontinuities in against mechanical stress. This field appears as a solid foundation for analyzing the behavior of the morphology of composites. This paper analyzes and evaluate the mechanical properties of composite of glass and polyester resin with geometrical discontinuities in (center hole and change of distance between the holes). The characterization was carried out by uniaxial tensile tests and fracture toughness. Thus they observed values of maximum stress at break for the laminates without holes, with a central hole and holes with varying spacing between the holes and the final characteristic of the fracture. To evaluate the possible influence of the presence of the central holes and the variation of the distance between the holes, the mechanical strength was determined for each case. There was also the factor of stress concentration, as was to be expected, it varies with the distance between the holes in the studied composites. The results obtained show that the presence of geometric discontinuity has harmful effect on the mechanical properties of the material, especially when the increased diameter of the central hole of 6 mm to 12 mm in diameter. The behavior to fracture of the studied composites, presented the final fracture of the LGM type (Side and Middle Greyhound) for central holes 6 and 12 mm and with the change of distance between holes 12 and 48 mm away, as for the change of distance between the holes of 6.2 mm away was AGM (Angle and Half Greyhound). The fracture toughness of the bulk composite, for two different thicknesses of plates (8 and 10 mm nominal values), was not satisfactory service for predicting the fracture of composites containing the concentrators strain studied.