STRAINS AND STRESSES OF THREE—LAYER COMPOSITE BARS AND BEAMS

Abstract

Summary New composite anisotropic materials (CM) glass, carbon and boric plastics are more and more frequently used in engineering construction. By tuning strength and stiffness characteristics of CM under tension or bending with their density or price it is possible to get laminated construction of maximum strength and stiffness and minimum mass or price. The purpose of this work is to analyse regularity of distribution of stiffness or strains and stresses in three-layer bars, subjected to tension or bending by changing geometric characteristics of layer, materials and their position in cross-section of bars. The bar layers were formed of carbon plastic (A), hot (Sk) and cold hardening (Sc) glass plastics and epoxy resin (D). Equations were obtained describing the alteration of bar and beam stiffness and the alteration of normal stresses, all depending on relative thichness Ψ of bar or beam. The relative thickness Ψ is the ratio of middle layer height to the whole height. It has been shown that maximum s...