New Methodology for Prestressing Fiber Composites

Abstract

The development of composite materials is characterized by the improvement of their mechanical properties (stiffness and strength) which have widened their application for structural fields like automobile, aerospace, and naval industries. The mechanical properties of composite materials can be upgraded during the manufacturing process by applying an appropriate load on the fibers and curing the corresponding matrix at certain temperature. For that purpose a machine was designed and built to exert load and heat on a composite of carbon fiber mat or glass fiber mat and matrix. The result is a rig agreed with horizontal tensiometer that can be called a prestress machine. This machine holds a certain tension on the fibers while the matrix is being cured. The main parts of the prestress machine are the mold, pulling crosshead, oven and sensors. This paper presents the steps of constructing and using this machine. Experimental investigations were carried out to determine the complete set of stiffness characteristics E_ij, G_ij, v_ij and strength characteristics σ_i,n, ε_i,n. The outcome results show that this machine can produce prestressed composite materials with much better mechanical properties comparing to those properties of the non-prestressed composite materials.