The paper studies stochastic dynamics of a two-degree-of-freedom system,where a primary linear system is connected to a nonlinear energy sink with cubic stiffness nonlinearity and viscous damping.While the primary mas...The paper studies stochastic dynamics of a two-degree-of-freedom system,where a primary linear system is connected to a nonlinear energy sink with cubic stiffness nonlinearity and viscous damping.While the primary mass is subjected to a zero-mean Gaussian white noise excitation,the main objective of this study is to maximise the efficiency of the targeted energy transfer in the system.A surrogate optimisation algorithm is proposed for this purpose and adopted for the stochastic framework.The optimisations are conducted separately for the nonlinear stiffness coefficient alone as well as for both the nonlinear stiffness and damping coefficients together.Three different optimisation cost functions,based on either energy of the system’s components or the dissipated energy,are considered.The results demonstrate some clear trends in values of the nonlinear energy sink coefficients and show the effect of different cost functions on the optimal values of the nonlinear system’s coefficients.展开更多
The tailored nanoparticles with a complex core/shell structure can satisfy a variety of demands, such as lattice misfit, shearability and coarsening resistance. In this research, core-shell nanoscale Al3(Yb, Er, Sc,Zr...The tailored nanoparticles with a complex core/shell structure can satisfy a variety of demands, such as lattice misfit, shearability and coarsening resistance. In this research, core-shell nanoscale Al3(Yb, Er, Sc,Zr, Li) composite particles were precipitated in Al-2 Li-0.1 Yb-0.1 Er-0.1 Sc-0.1 Zr(wt%) alloy through the double-aging treatment, in which the core was(Yb, Er, Sc, Zr)-rich formed at 300°C and the shell was Li-rich formed at 150°C. The coarsening kinetics and precipitate size distributions(PSDs) of Al3(Yb, Er, Sc,Zr, Li) particles aged at 150°C previously aged at 300°C for 24 h showed a better fit to the relation of 2∝ kt and normal distribution, indicating that the coarsening of precipitates was controlled by interface reaction, not diffusion. The Orowan bypass strengthening was operative mechanism at 150°C.展开更多
基金funding for this work from NSF-CMMI 2009270 and EPSRC EP/V034391/1.
文摘The paper studies stochastic dynamics of a two-degree-of-freedom system,where a primary linear system is connected to a nonlinear energy sink with cubic stiffness nonlinearity and viscous damping.While the primary mass is subjected to a zero-mean Gaussian white noise excitation,the main objective of this study is to maximise the efficiency of the targeted energy transfer in the system.A surrogate optimisation algorithm is proposed for this purpose and adopted for the stochastic framework.The optimisations are conducted separately for the nonlinear stiffness coefficient alone as well as for both the nonlinear stiffness and damping coefficients together.Three different optimisation cost functions,based on either energy of the system’s components or the dissipated energy,are considered.The results demonstrate some clear trends in values of the nonlinear energy sink coefficients and show the effect of different cost functions on the optimal values of the nonlinear system’s coefficients.
基金supported financially by the National Natural Science Foundation of China(Nos.51671063,51771060,51871068 and 51971071)the Domain Foundation of Equipment Advance Research of 13th Five-year Plan(No.61409220118)+2 种基金the Fundamental Research Funds for the Central Universities(No.HEUCFG201834)the Harbin City Application Technology Research and Development Project(Nos.2015RQXXJ001 and 2017RAQXJ032)the Ph.D.Student Research and Innovation Fund of the Fundamental Research Funds for the Central Universities(No.3072019GIP1013)。
文摘The tailored nanoparticles with a complex core/shell structure can satisfy a variety of demands, such as lattice misfit, shearability and coarsening resistance. In this research, core-shell nanoscale Al3(Yb, Er, Sc,Zr, Li) composite particles were precipitated in Al-2 Li-0.1 Yb-0.1 Er-0.1 Sc-0.1 Zr(wt%) alloy through the double-aging treatment, in which the core was(Yb, Er, Sc, Zr)-rich formed at 300°C and the shell was Li-rich formed at 150°C. The coarsening kinetics and precipitate size distributions(PSDs) of Al3(Yb, Er, Sc,Zr, Li) particles aged at 150°C previously aged at 300°C for 24 h showed a better fit to the relation of 2∝ kt and normal distribution, indicating that the coarsening of precipitates was controlled by interface reaction, not diffusion. The Orowan bypass strengthening was operative mechanism at 150°C.
