As a novel vibration absorber,Nitinol-steel wire rope(NiTi-ST)has rarely been studied on vibration suppression for lattice sandwich beams in supersonic airflow.In this paper,NiTi-ST with nonlinear stiffness and hyster...As a novel vibration absorber,Nitinol-steel wire rope(NiTi-ST)has rarely been studied on vibration suppression for lattice sandwich beams in supersonic airflow.In this paper,NiTi-ST with nonlinear stiffness and hysteretic damping is embedded in a lattice sandwich beam to control the beam's vibration.The nonlinear restoring and hysteretic damping force of NiTi-ST are treated as polynomials.The dynamic equation is established based on Hamilton's principle.The amplitude responses of the beam with different NiTi-ST configurations are calculated.The vibration-suppression effects and energy dissipation of lattice sandwich beam with different NiTi-ST configurations under different air velocities are also compared.The frequency-domain and time-domain methods are used to analyze the structural aeroelastic properties.Simulation results show that the use of NiTi-ST can significantly suppress excessive vibration of a lattice sandwich beam in supersonic airflow.展开更多
Machining of shape memory alloys(SMAs)without losing the shape memory effect could immensely extend their applications.Herein,the wire electric discharge machining process was used to machine NiTi—a shape memory allo...Machining of shape memory alloys(SMAs)without losing the shape memory effect could immensely extend their applications.Herein,the wire electric discharge machining process was used to machine NiTi—a shape memory alloy.The experimental methodology was designed using a Box-Behnken design approach of the response surface methodology.The effects of input variables including pulse on time,pulse off time,and current were investigated on the material removal rate,surface roughness,and microhardness.ANOVA tests were performed to check the robustness of the generated empirical models.Optimization of the process parameters was performed using a newly formulated,highly efficient heat transfer search algorithm.Validation tests were conducted and extended for analyzing the retention of the shape memory effect of the machined surface by differential scanning calorimetry.In addition,2D and 3D Pareto curves were generated that indicated the trade-offs between the selected output variables during the simultaneous output variables using the multi-objective heat transfer search algorithm.The optimization route yielded encouraging results.Single objective optimization yielded a maximum material removal rate of 1.49 mm^(3)/s,maximum microhardness 462.52 HVN,and minimum surface roughness 0.11μm.The Pareto curves showed conflicting effects during the wire electric discharge machining of the shape memory alloy and presented a set of optimal non-dominant solutions.The shape memory alloy machined using the optimized process parameters even indicated a shape memory effect similar to that of the starting base material.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
基金supported by the National Natural Science Foundation of China(Project Nos.12022213 and 11902203)Liaoning Educational Committee Scientific Research Project in General(JYT2020035).
文摘As a novel vibration absorber,Nitinol-steel wire rope(NiTi-ST)has rarely been studied on vibration suppression for lattice sandwich beams in supersonic airflow.In this paper,NiTi-ST with nonlinear stiffness and hysteretic damping is embedded in a lattice sandwich beam to control the beam's vibration.The nonlinear restoring and hysteretic damping force of NiTi-ST are treated as polynomials.The dynamic equation is established based on Hamilton's principle.The amplitude responses of the beam with different NiTi-ST configurations are calculated.The vibration-suppression effects and energy dissipation of lattice sandwich beam with different NiTi-ST configurations under different air velocities are also compared.The frequency-domain and time-domain methods are used to analyze the structural aeroelastic properties.Simulation results show that the use of NiTi-ST can significantly suppress excessive vibration of a lattice sandwich beam in supersonic airflow.
文摘Machining of shape memory alloys(SMAs)without losing the shape memory effect could immensely extend their applications.Herein,the wire electric discharge machining process was used to machine NiTi—a shape memory alloy.The experimental methodology was designed using a Box-Behnken design approach of the response surface methodology.The effects of input variables including pulse on time,pulse off time,and current were investigated on the material removal rate,surface roughness,and microhardness.ANOVA tests were performed to check the robustness of the generated empirical models.Optimization of the process parameters was performed using a newly formulated,highly efficient heat transfer search algorithm.Validation tests were conducted and extended for analyzing the retention of the shape memory effect of the machined surface by differential scanning calorimetry.In addition,2D and 3D Pareto curves were generated that indicated the trade-offs between the selected output variables during the simultaneous output variables using the multi-objective heat transfer search algorithm.The optimization route yielded encouraging results.Single objective optimization yielded a maximum material removal rate of 1.49 mm^(3)/s,maximum microhardness 462.52 HVN,and minimum surface roughness 0.11μm.The Pareto curves showed conflicting effects during the wire electric discharge machining of the shape memory alloy and presented a set of optimal non-dominant solutions.The shape memory alloy machined using the optimized process parameters even indicated a shape memory effect similar to that of the starting base material.
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.
