eng Science and Education Publishing American Journal of Mechanical Engineering 2328-4110 2016-12-17 4 7 289 292 10.12691/ajme-4-7-11 AJME20164711 article Juraj Šarloši juraj.sarlosi@gmail.com 1 Jozef Bocko 1 Department of Applied Mechanics and Mechanical Engineering, Technical University in Košice, Košice, Slovakia In this article we deal with deriving the elastic modulus of composite materials. Modulus values in each direction are various, for example in parallel direction and the perpendicular direction. It depends on the material properties for fibers from material for matrix, density of fibers in the composite material, as well as on whether it is a single or multi-layer composite material and from the direction the filaments in the matrix. http://pubs.sciepub.com/ajme/4/7/11/ajme-4-7-11.pdf fibers matrix composite material effective modulus transverse modulus improved formulas in-plane sher modulus poison's ratio mixture rules