This research presents a numerical simulation methodology for optimizing circular composite overlays’dimensions and pressure characteristics with orthotropic mechanical properties,specifically,for metal conduits with...This research presents a numerical simulation methodology for optimizing circular composite overlays’dimensions and pressure characteristics with orthotropic mechanical properties,specifically,for metal conduits with temperature-dependent elastoplastic behavior.The primary objective of the proposed method is to prevent crack propagation during pressure surges from operational to critical levels.This study examines the“Beineu-Bozoy-Shymkent”steel gas conduit,examining its performance across a temperature range of−40 to+50℃.This work builds on prior research on extended avalanche destruction in steel gas conduits and crack propagation prevention techniques.Theanalysis was conducted using a dynamic finite-element approach with the ANSYS-19.2/ExplicitDynamics software.Simulations of unprotected conduits revealed that increasing gas-dynamic pressure can convert a partial-depth crack into a through-crack,extending longitudinally to approximately seven times its initial length.Notably,at T=+50℃,the developed crack length was 1.2%longer than that at T=−40℃,highlighting the temperature sensitivity of crack progression.The modeling results indicate that crack propagation can be effectively controlled using a circular composite overlay with a thickness between 37.5%and 50%of the crack depth and a length approximately five times that of the initial crack,centered symmetrically over the crack.In addition,preliminary stress analysis indicated that limiting the overlay-induced pressure to 5%of the operational pressure effectively arrested crack growth without generating significant stress concentrations near the overlay boundaries,thereby preventing conduit integrity.展开更多
To determine the fracture characteristics of asphalt mixture a novel fracture test with modified loading modes loading fixtures and the control system of the conventional overlay tester is implemented by the asphalt m...To determine the fracture characteristics of asphalt mixture a novel fracture test with modified loading modes loading fixtures and the control system of the conventional overlay tester is implemented by the asphalt material performance tester AMPT .In order to evaluate the validity of the proposed fracture test four different loading rates including 1 2 3 and 4 mm/min are examined in the AMPT. The results indicate that the fracture behavior is similar to creep at a low loading rate and does not show significant marginal tail extension at a high loading rate.It clearly shows the phase of crack initiation crack propagation and fracture at a loading rate of 3 mm/min. Besides eight fracture parameters such as fracture energy tensile strength and tensile modulus are applied to evaluate the fracture characteristics of asphalt mixture.Development of the overlay tester for the fracture test of asphalt mixture can be considered as a new fracture test of asphalt mixture.展开更多
基金supported by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan(Grant No.AP19680589).
文摘This research presents a numerical simulation methodology for optimizing circular composite overlays’dimensions and pressure characteristics with orthotropic mechanical properties,specifically,for metal conduits with temperature-dependent elastoplastic behavior.The primary objective of the proposed method is to prevent crack propagation during pressure surges from operational to critical levels.This study examines the“Beineu-Bozoy-Shymkent”steel gas conduit,examining its performance across a temperature range of−40 to+50℃.This work builds on prior research on extended avalanche destruction in steel gas conduits and crack propagation prevention techniques.Theanalysis was conducted using a dynamic finite-element approach with the ANSYS-19.2/ExplicitDynamics software.Simulations of unprotected conduits revealed that increasing gas-dynamic pressure can convert a partial-depth crack into a through-crack,extending longitudinally to approximately seven times its initial length.Notably,at T=+50℃,the developed crack length was 1.2%longer than that at T=−40℃,highlighting the temperature sensitivity of crack progression.The modeling results indicate that crack propagation can be effectively controlled using a circular composite overlay with a thickness between 37.5%and 50%of the crack depth and a length approximately five times that of the initial crack,centered symmetrically over the crack.In addition,preliminary stress analysis indicated that limiting the overlay-induced pressure to 5%of the operational pressure effectively arrested crack growth without generating significant stress concentrations near the overlay boundaries,thereby preventing conduit integrity.
基金The National Natural Science Foundation of China(No.51178114)the Chinese Western Transportation Construction Technology Project of Transportation Ministry(No.2009318000086)
文摘To determine the fracture characteristics of asphalt mixture a novel fracture test with modified loading modes loading fixtures and the control system of the conventional overlay tester is implemented by the asphalt material performance tester AMPT .In order to evaluate the validity of the proposed fracture test four different loading rates including 1 2 3 and 4 mm/min are examined in the AMPT. The results indicate that the fracture behavior is similar to creep at a low loading rate and does not show significant marginal tail extension at a high loading rate.It clearly shows the phase of crack initiation crack propagation and fracture at a loading rate of 3 mm/min. Besides eight fracture parameters such as fracture energy tensile strength and tensile modulus are applied to evaluate the fracture characteristics of asphalt mixture.Development of the overlay tester for the fracture test of asphalt mixture can be considered as a new fracture test of asphalt mixture.
