The dynamic stiffness of polyester rope presents a complex mechanical performance,and the search for an appropriate calculation method to simulate this property is important.Distorted simulation results eventually yie...The dynamic stiffness of polyester rope presents a complex mechanical performance,and the search for an appropriate calculation method to simulate this property is important.Distorted simulation results eventually yield inaccurate line tension and vessel offset predictions,with the inaccuracy of vessel offset being particularly large.This paper proposes a flexible calculation method for the dynamic behavior of polyester rope based on the dynamic stiffness model.A real-time varying stiffness model of polyester rope is employed to simulate tension response through rope strain monitoring.Consequently,a simulation program is developed,and related case studies are conducted to explore the differences between the proposed method and analytical procedure of the DNV standard.Orcaflex is used to simulate the results of the latter procedure for comparison.Results show the convenience and straightforwardness of the procedure in the selection of an approximate dynamic stiffness model for polyester rope,which leads to an engineering-oriented approach.However,the proposed method is related to line property,which can directly reflect the dynamic behavior of polyester rope.Thus,a flexible calculation method may provide a reference for the simulation of the dynamic response of polyester mooring systems.展开更多
There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fi...There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fig. 1), and tracing the temporal and spacial historical distribution of the bivalves very capable of dispersion, some Jurassic bivalve biogeographic items, particularly the biogeographic relations, have been lit up. In the known 21 taxa of the Jurassic Pectinoida and Ostreoida from the main ridge of the Tanggula Mountains, there are 12 (57%) common and coeval species in northern Tethys, 13 (62%) common and coeval species in southern Tethys and 12 (57%) in Kachchh—southern Xizang area. It has demonstrated that there existed intermigration of bivalves between Tanggula and various parts of Tethys. Although there is no coeval species between Tanggula and western Australia, in these two areas there exist 6 (29%) close range common species of which 4 (19%) coevaity existed in western Australia and India Plate. Tanggula fauna is, therefore, still very close to that of western Australia. However, there are 15 (71%) common and 14 (67%) coevality species between the main ridge of the Tanggula Mountains and northwestern Europe, among the common species, 8 (38%) ones have lower limitation (first occurrence) in northwestern Europe but only 2 (10%) taxa are older in the main ridge of the Tanggula Mountains. It is very clear that pectinite and ostrea fauna of Tethys, particularly the main ridge of the Tanggula Mountains and Europe had very close relation and most Tanggula’s or northern Tethyan taxa migrated from northwestern Europe.展开更多
A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is cou...A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.展开更多
The dynamic behavior of a bridge-erecting machine, carrying a moving mass suspended by a wire rope, is investigated. The bridge-erecting machine is modelled by a simply supported uniform beam, and a massless equivale...The dynamic behavior of a bridge-erecting machine, carrying a moving mass suspended by a wire rope, is investigated. The bridge-erecting machine is modelled by a simply supported uniform beam, and a massless equivalent ＂spring-damper＂ system with an effective spring constant and an effective damping coefficient is used to model the moving mass suspended by the wire rope. The suddenly applied load is represented by a unitary Dirac Delta function. With the expansion method, a simple closed-form solution for the equation of motion with the replaced spring-damper-mass system is formulated. The characters of the rope are included in the derivation of the differential equation of motion for the system. The numerical examples show that the effects of the damping coefficient and the spring constant of the rope on the deflection have significant variations with the loading frequency. The effects of the damping coefficient and the spring constant under different beam lengths are also examined. The obtained results validate the presented approach, and provide significant references in the design process of bridgeerecting machines.展开更多
Accurate understanding the behavior of spiral rope is complicated due to their complex geometry and complex contact conditions between the wires.This study proposed the finite element models of spiral ropes subjected ...Accurate understanding the behavior of spiral rope is complicated due to their complex geometry and complex contact conditions between the wires.This study proposed the finite element models of spiral ropes subjected to tensile loads.The parametric equations developed in this paper were implemented for geometric modeling of ropes.The 3D geometric models with different twisting manner,equal diameters of wires were generated in details by using Pro/ENGINEER software.The results of the present finite element analysis were on an acceptable level of accuracy as compared with those of theoretical and experimental data.Further development is ongoing to analysis the equivalent stresses induced by twisting manner of cables.The twisting manner of wires was important to spiral ropes in the three wire layers and the outer twisting manner of wires should be contrary to that of the second layer,no matter what is the first twisting manner of wires.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51879047).
文摘The dynamic stiffness of polyester rope presents a complex mechanical performance,and the search for an appropriate calculation method to simulate this property is important.Distorted simulation results eventually yield inaccurate line tension and vessel offset predictions,with the inaccuracy of vessel offset being particularly large.This paper proposes a flexible calculation method for the dynamic behavior of polyester rope based on the dynamic stiffness model.A real-time varying stiffness model of polyester rope is employed to simulate tension response through rope strain monitoring.Consequently,a simulation program is developed,and related case studies are conducted to explore the differences between the proposed method and analytical procedure of the DNV standard.Orcaflex is used to simulate the results of the latter procedure for comparison.Results show the convenience and straightforwardness of the procedure in the selection of an approximate dynamic stiffness model for polyester rope,which leads to an engineering-oriented approach.However,the proposed method is related to line property,which can directly reflect the dynamic behavior of polyester rope.Thus,a flexible calculation method may provide a reference for the simulation of the dynamic response of polyester mooring systems.
文摘There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fig. 1), and tracing the temporal and spacial historical distribution of the bivalves very capable of dispersion, some Jurassic bivalve biogeographic items, particularly the biogeographic relations, have been lit up. In the known 21 taxa of the Jurassic Pectinoida and Ostreoida from the main ridge of the Tanggula Mountains, there are 12 (57%) common and coeval species in northern Tethys, 13 (62%) common and coeval species in southern Tethys and 12 (57%) in Kachchh—southern Xizang area. It has demonstrated that there existed intermigration of bivalves between Tanggula and various parts of Tethys. Although there is no coeval species between Tanggula and western Australia, in these two areas there exist 6 (29%) close range common species of which 4 (19%) coevaity existed in western Australia and India Plate. Tanggula fauna is, therefore, still very close to that of western Australia. However, there are 15 (71%) common and 14 (67%) coevality species between the main ridge of the Tanggula Mountains and northwestern Europe, among the common species, 8 (38%) ones have lower limitation (first occurrence) in northwestern Europe but only 2 (10%) taxa are older in the main ridge of the Tanggula Mountains. It is very clear that pectinite and ostrea fauna of Tethys, particularly the main ridge of the Tanggula Mountains and Europe had very close relation and most Tanggula’s or northern Tethyan taxa migrated from northwestern Europe.
基金Project supported by the National Natural Science Foundation of China(No.11772205)the Scientific Research Fund of Liaoning Provincial Education Department(No.L201703)+1 种基金the Liaoning Revitalization Talent Program(No.XLYC1807172)the Training Project of Liaoning Higher Education Institutions in Domestic and Overseas(No.2018LNGXGJWPY-YB008)
文摘A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.
基金supported by the National Natural Science Foundation of China(No.11472179)
文摘The dynamic behavior of a bridge-erecting machine, carrying a moving mass suspended by a wire rope, is investigated. The bridge-erecting machine is modelled by a simply supported uniform beam, and a massless equivalent ＂spring-damper＂ system with an effective spring constant and an effective damping coefficient is used to model the moving mass suspended by the wire rope. The suddenly applied load is represented by a unitary Dirac Delta function. With the expansion method, a simple closed-form solution for the equation of motion with the replaced spring-damper-mass system is formulated. The characters of the rope are included in the derivation of the differential equation of motion for the system. The numerical examples show that the effects of the damping coefficient and the spring constant of the rope on the deflection have significant variations with the loading frequency. The effects of the damping coefficient and the spring constant under different beam lengths are also examined. The obtained results validate the presented approach, and provide significant references in the design process of bridgeerecting machines.
基金funded by International S&T Cooperation Program of China(2011DFA72120)and NSFC(No.51205272).
文摘Accurate understanding the behavior of spiral rope is complicated due to their complex geometry and complex contact conditions between the wires.This study proposed the finite element models of spiral ropes subjected to tensile loads.The parametric equations developed in this paper were implemented for geometric modeling of ropes.The 3D geometric models with different twisting manner,equal diameters of wires were generated in details by using Pro/ENGINEER software.The results of the present finite element analysis were on an acceptable level of accuracy as compared with those of theoretical and experimental data.Further development is ongoing to analysis the equivalent stresses induced by twisting manner of cables.The twisting manner of wires was important to spiral ropes in the three wire layers and the outer twisting manner of wires should be contrary to that of the second layer,no matter what is the first twisting manner of wires.
