Long-Term Durability of Glass-Fiber-Reinforced Composites under Operation in Pulp and Reactant Pipelines

Authors: Chekalkin A.A.; Babushkin A.V.; Kotov A.G.; Shakleina S.E.

Source: Mechanics of Composite Materials, Volume 39, Number 3, May 2003 , pp. 273-282(10)

Publisher: Springer

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Abstract:

Composite pipes 215 mm in diameter with a 6-mm wall, 3-mm functional layer, and ±60° glass-fiber-reinforced plastic (GFRP) layers were examined by means of microstructural analysis and mechanical testing. Three types of pipes were considered: unused, after a five-year operation at a pressure of 0.6 MPa and temperature of 70°C, and after a five-year operation at 0.6 MPa and 20°C. The GFRP load-carrying layer and the interfaces were investigated by a metallographic optical microscope, a computerized microscanning equipment, and a software image processing package. The initial and accumulated damages in the microstructure of the composite and interfaces were examined. The mechanical properties of the pipes after a long-term operation were examined on two-layer specimens in three-point bending. The stiffness and strength characteristics were measured in the axial and circumferential directions under tensile and compressive loads at elevated temperatures. Composite pipes, 8 m in length and 215 mm in diameter, were simulated numerically as shells of revolution. The shell model was corrected by a refined Timoshenko theory and a dual-modulus temperature-dependent model of stiffness for the multilayer composite structure. The strength margin of the composite pipes was determined based on real strength properties.

Keywords: composite; glass-fiber-reinforced plastic; microstructure; fractography; mechanical properties; pipeline

Language: English

Document Type: Research article

Affiliations: 1: Perm' State Technical University, Perm', Russia

Publication date: 2003-05-01