Gear teeth in gear transmission systems suffer seriously from fatigue failure during service. In this work, a 2 D double-tooth model was constructed with periodic boundary conditions. The fatigue fracture behavior of ...Gear teeth in gear transmission systems suffer seriously from fatigue failure during service. In this work, a 2 D double-tooth model was constructed with periodic boundary conditions. The fatigue fracture behavior of gear teeth was analyzed using the extended finite element method(XFEM), with emphases on the impacts of initial crack geometries and cyclic load factors. The results suggested that the shortest fatigue life is expected for 0° orientation cracks initiating at the maximum principal stress. Cracks that initiate closer to the bottom land of gear tooth are relatively safe. Moreover, to evaluate the fatigue load conditions, load ratio, load range, and mean load should be all taken into considerations. Further XFEM simulation for material selection was performed to guide the gear design. Among various material parameters, the material constant C and tensile strength are the most significant ones in determining the fatigue life.展开更多
Causes of scale deposition in flue gas turbine expander of FCCU were analyzed based on some aspects,including the types and operating conditions of flue gas turbines,properties and composition of feedstocks and cataly...Causes of scale deposition in flue gas turbine expander of FCCU were analyzed based on some aspects,including the types and operating conditions of flue gas turbines,properties and composition of feedstocks and catalysts,and operating conditions of the reactor and regenerator.Some countermeasures were proposed for preventing scale deposition in flue gas turbine of FCCU.展开更多
A high-precision identification method for steam turbine rotor crack is presented. By providing me nrst three measured natural frequencies, contours for the specified natural frequency are plotted in the same coordi- ...A high-precision identification method for steam turbine rotor crack is presented. By providing me nrst three measured natural frequencies, contours for the specified natural frequency are plotted in the same coordi- nate, and the intersection of the three curves predicts the crack location and size. The cracked rotor system is mod- eled using B-spline wavelet on the interval （BSWI） finite element method, and a method based on empirical mode decomposition （EMD） and Laplace wavelet is implemented to improve the identification precision of the first three measured natural frequencies. Compared with the classical nondestructive testing, the presented method shows its effectiveness and reliability. It is feasible to apply this method to the online health monitoring for rotor structure.展开更多
Within a context of sustainable development, innovative processes for various applications to recycle rubber are put in place to make aggregates or crumb rubber. These uses include sports floor coverings, to manufactu...Within a context of sustainable development, innovative processes for various applications to recycle rubber are put in place to make aggregates or crumb rubber. These uses include sports floor coverings, to manufacture of sealants, sound absorbing walls, to make roads, as an alternative fuel in cement kilns, etc. In this study, the addition of crumb rubber to mortar was investigated through optical and mechanical tests. The results showed that the incorporation of crumb rubber from used tires into mortar produced a better resistance to shrinkage cracking, but a compressive strength/tensile is reduced. This feature could lend itself to making playgrounds and sports grounds more absorbing and flexible, which would allow a more significant fall to be withstood without injury and consequently enhance the safety of playgrounds.展开更多
基金Project(2018YFE0306100) supported by the National MCF Energy R&D Program of ChinaProject supported by the State Key Laboratory of Powder Metallurgy,Central South University,China
文摘Gear teeth in gear transmission systems suffer seriously from fatigue failure during service. In this work, a 2 D double-tooth model was constructed with periodic boundary conditions. The fatigue fracture behavior of gear teeth was analyzed using the extended finite element method(XFEM), with emphases on the impacts of initial crack geometries and cyclic load factors. The results suggested that the shortest fatigue life is expected for 0° orientation cracks initiating at the maximum principal stress. Cracks that initiate closer to the bottom land of gear tooth are relatively safe. Moreover, to evaluate the fatigue load conditions, load ratio, load range, and mean load should be all taken into considerations. Further XFEM simulation for material selection was performed to guide the gear design. Among various material parameters, the material constant C and tensile strength are the most significant ones in determining the fatigue life.
文摘Causes of scale deposition in flue gas turbine expander of FCCU were analyzed based on some aspects,including the types and operating conditions of flue gas turbines,properties and composition of feedstocks and catalysts,and operating conditions of the reactor and regenerator.Some countermeasures were proposed for preventing scale deposition in flue gas turbine of FCCU.
基金National Natural Science Foundation of China(No.51225501No.51035007)Program for Changjiang Scholars and Innovative Research Team in University
文摘A high-precision identification method for steam turbine rotor crack is presented. By providing me nrst three measured natural frequencies, contours for the specified natural frequency are plotted in the same coordi- nate, and the intersection of the three curves predicts the crack location and size. The cracked rotor system is mod- eled using B-spline wavelet on the interval （BSWI） finite element method, and a method based on empirical mode decomposition （EMD） and Laplace wavelet is implemented to improve the identification precision of the first three measured natural frequencies. Compared with the classical nondestructive testing, the presented method shows its effectiveness and reliability. It is feasible to apply this method to the online health monitoring for rotor structure.
文摘Within a context of sustainable development, innovative processes for various applications to recycle rubber are put in place to make aggregates or crumb rubber. These uses include sports floor coverings, to manufacture of sealants, sound absorbing walls, to make roads, as an alternative fuel in cement kilns, etc. In this study, the addition of crumb rubber to mortar was investigated through optical and mechanical tests. The results showed that the incorporation of crumb rubber from used tires into mortar produced a better resistance to shrinkage cracking, but a compressive strength/tensile is reduced. This feature could lend itself to making playgrounds and sports grounds more absorbing and flexible, which would allow a more significant fall to be withstood without injury and consequently enhance the safety of playgrounds.
