EXAMINATION OF THE INFLUENCE OF SHEAR MICRO- GEOMETRICAL PROPERTIES ON TRANSVERSE ELASTICITY THE MODULUS OF ROVING COMPOSITE MATERIALS USED IN CRITICAL CONSTRUCTIONS Piotr Wolszczak, Radosław Cechowicz Lublin University of Technology, Automation Faculty, Poland p.wolszczak@pollub.pl ABSTRACT Monitoring of quality is an important task in the production process of critical supporting structures made from roving composites. Results from the research performed on the production samples of girders of helicopter blades presented in this paper, suggest that geometrical measures can be used for prediction of material strength and durability. The correlation between geometrical measurements of shear microstructure and values of the elasticity modulus determined in the transverse shear strength test by short beam method was assessed. 1. INTRODUCTION Composites made up of fibres (glass or carbon) with a circular cross section, arranged unidirectionally and embedded in an epoxy resin matrix constitute an interesting group among machine building materials. The composite of hard, brittle fibres immersed in an epoxy resin of significantly lower strength is strongly anisotropic. Strength of the composite depends on: the direction of load in relation to the fibre axis, the strength of the components, the adhesive forces between the fibres and the resin, on the relative volume of the components and on the geometrical arrangement of fibres in a cross-section. The geometrical arrangement of fibres depends on the manufacturing process [1, 2, 3, 4]. One of the main problems in material strength analysis is to determine the geometrical distribution of fibres in a sample and obtain a measure that can be related to material strength. A literature review assumes that the geometric properties of the microstructure are random [4]. However, in theoretical considerations of composite strength, the following assumptions are made [3]: composite components are homogeneous (there are no defects such as bubbles and impurities in the matrix volume), component materials are isotropic (anisotropy of the fibres is ignored), elastic deformation of composite ingredients is linear, a combination of fibres and matrix is ideal and the strength of the adhesion exceeds the strength of the warp (no slip and