Researching strength of glued composite compounds with thermal-tension fittings

Abstract

Problem. A review of methods for determining the strength of reinforced bonded and mechanical joints is given. The need to study glued joints is aimed at replacing the welding operation of bar reinforcement with a more economical gluing operation. Types of samples and structural dimensions for testing a layer in glued reinforced joints for tensile and shear are presented. A set of studies is proposed for the selection of composite materials when filling the intercostal cavity between the rods and the sleeve opening to reveal the maximum strength of such an integral connection. A diagram of the static tension of a glued reinforced joint is constructed, which has a jump-like nature when the coordinates P * - strain e are destroyed, which is associated with the gradual destruction of the fibers of the wound layer. A methodology for the manufacture of glued composite joints for reinforcing sleeves is proposed, and the tensile stress σ * and shear stress τ * are determined for them.Goal. Reinforced polymer composite materials are applied for bonding epoxy resin-coated rods after the selection of their components, and on this basis the strength of the bonded joints is compared with the strength of such reinforcement and the strength of its welded joints. Methodology. A methodology for the manufacture of glued composite joints is proposed for reinforcing bars – a sleeve and, specifically, the tensile stress σ* and shear τ* for them. Results. By sampling from five grades of composite materials, the maximum strength of the composite bonded joint layer based on the reinforcement of basalt fiberepoxy resin EDP-22 was established, provided that the ratios are 1:10 of their weight units, while such a composite layer is 90% and 71 % of the strength of thermally stressed reinforcement made of 35HS and 25H2S steels and exceeds by 24 % and 18 % the strength of the weld of their welded joints, respectively. Originality. For the first time, a methodology for the manufacture of bonded composite joints reinforcing rods – sleeve was proposed and the highest strength of the composite layer of the bonded compound based on the reinforcement of EDP-22 basalt fiber-epoxy resin was established. Practical value. Since the strength of glued joints takes intermediate values between the strength of thermally stressed reinforcement and its welded joints, they can be successfully recommended instead of the welding operation for gluing reinforcing bars with a sleeve with a screw profile of the hole by filling the intercostal cavity with a composite filler of basalt fiber – an epoxy binder based on EDP-22 with a ratio of 1:10 weight units when it comes to the manufacture of precarriage trusses of bridges, overall construction methods ore and others.