Fluctuated loadings from currents,waves and sea ground motions are observed on offshore steel pipelines,and they will result in small cracks to propagate continuously and cause unexpected damage to offshore/geotechnic...Fluctuated loadings from currents,waves and sea ground motions are observed on offshore steel pipelines,and they will result in small cracks to propagate continuously and cause unexpected damage to offshore/geotechnical infrastructures.In spite of the availability of efficient techniques and high-power computers for solving crack problems,investigations on the fatigue life of offshore pipelines with 3D interacting cracks are still rarely found in open literature.In the current study,systematic numerical investigations are performed on fatigue crack growth behaviours of offshore pipelines containing coplanar and non-coplanar cracks.Extended finite element method(XFEM)is adopted to simulate the fatigue crack growth.The qualitative validations of numerical results are made for certain cases with available experimental results.Parametric studies are conducted to investigate the influences of various important parameters on fatigue crack growth.The results will be helpful to assess the fatigue behaviours of steel pipeline with 3D interacting cracks.展开更多
Flexoelectric effect can be used to design actuators to control engi-neering structures including beams,plates,and shells.Multiple flexo-electric actuators method has the advantage of less stress concentration and bet...Flexoelectric effect can be used to design actuators to control engi-neering structures including beams,plates,and shells.Multiple flexo-electric actuators method has the advantage of less stress concentration and better control effect,but the mode-dependent optimal actuator locations could influence the flexoelectric actuation effect significantly.In this work,a neural network model is established to study the optimal combinations of multiple flexoelectric actuators on a rectangular plate.In the physical model,an atomic force micro-scope(AFM)probe was employed to generate an electric field gradient in the flexoelectric patch,so that flexoelectric control force and moment can be obtained.Multiple flexoelectric actuators on the plate was considered.Case studies showed that the flexoelectricity induced stress mainly concentrate near the probe,the size and shape of the flexoelectric patch have limited effect on the actuation,hence,only the actuator positions were choosing as the input of the ANN model.Using the prediction of the neural network model,the driving effect of a large number of actuators at different positions can be quickly obtained,and the optimal position of the actuator can be analyzed more accurately.展开更多
基金The authors would like to acknowledge the financial support for this project under Nanyang Technological University,Singapore’s Academic Research Fund(AcRF)Tier 1 Grant No.RG 168/16.
文摘Fluctuated loadings from currents,waves and sea ground motions are observed on offshore steel pipelines,and they will result in small cracks to propagate continuously and cause unexpected damage to offshore/geotechnical infrastructures.In spite of the availability of efficient techniques and high-power computers for solving crack problems,investigations on the fatigue life of offshore pipelines with 3D interacting cracks are still rarely found in open literature.In the current study,systematic numerical investigations are performed on fatigue crack growth behaviours of offshore pipelines containing coplanar and non-coplanar cracks.Extended finite element method(XFEM)is adopted to simulate the fatigue crack growth.The qualitative validations of numerical results are made for certain cases with available experimental results.Parametric studies are conducted to investigate the influences of various important parameters on fatigue crack growth.The results will be helpful to assess the fatigue behaviours of steel pipeline with 3D interacting cracks.
文摘Flexoelectric effect can be used to design actuators to control engi-neering structures including beams,plates,and shells.Multiple flexo-electric actuators method has the advantage of less stress concentration and better control effect,but the mode-dependent optimal actuator locations could influence the flexoelectric actuation effect significantly.In this work,a neural network model is established to study the optimal combinations of multiple flexoelectric actuators on a rectangular plate.In the physical model,an atomic force micro-scope(AFM)probe was employed to generate an electric field gradient in the flexoelectric patch,so that flexoelectric control force and moment can be obtained.Multiple flexoelectric actuators on the plate was considered.Case studies showed that the flexoelectricity induced stress mainly concentrate near the probe,the size and shape of the flexoelectric patch have limited effect on the actuation,hence,only the actuator positions were choosing as the input of the ANN model.Using the prediction of the neural network model,the driving effect of a large number of actuators at different positions can be quickly obtained,and the optimal position of the actuator can be analyzed more accurately.
