Materials Science Forum Vol. 813

Abstract: Linear elastic fracture mechanics (LEFM) indicates that crack-like flaws tend to intensify stress in brittle materials with stress intensity proportional to the square root of the crack size. Under given loading, monolithic brittle materials can only endure cracks smaller than a critical size. In this paper, however, our exploration into the stress state of nacreous composites shows that the crack-induced stress intensification/concentration and its dependence on crack size can be suppressed in composites with ‘brick-and-mortar’ structure. This feature can be attributed to the unique ‘brick-and-mortar’ (B-and-M) structure and the complementary dissimilarity between ‘brick’ (e.g. minerals) and ‘mortar’ (e.g. proteins) phases in mechanical properties. Our findings provide a profound insight into the origin of high strength and high toughness in nacreous composites.

Abstract: The major challenge for producing and manufacturing risers for oil and gas production is to make them light weight so as to reduce the operational cost and improve the overall system requirements to make them an attractive option for marine and offshore industries. In the current research, the composite and metal-composite pipes (1) GFRP only (2) Al-GFRP and (3) PE-GFRP have been manufactured using filament winding machine operated using CADFIL and CADWIND CNC packages. The use of liners (Al and PE) has ensured the fluid tightness and collapse resistance of the pipe system. Small prototype pipes are manufactured based on optimized pipe design parameters for collapse under external pressure and burst under internal pressure using ANSYS 13 FEA analysis software. Experiments are conducted to verify the axial and hoop compressive strengths of the pipes with analytical results. The details of pipe manufacturing process using filament winding machine, simulation procedure to optimize the pipe parameters and validation of the simulation results with experimental results are the focal points of the current work.