An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties ...An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties of MFG porous plates change according to the length,width,and thickness directions for various materials and the porosity distribution which can be widely applied in many fields of engineering and defence technology.Especially,new porous rules that depend on spatial coordinates and grading indexes are proposed in the present work.Applying Hamilton's principle and the refined higher-order shear deformation plate theory,the governing equation of motion of an MFG porous rectangular plate in a fluid medium(the fluid-plate system)is obtained.The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to compute the extra mass.The GalerkinVlasov solution is used to solve and give natural frequencies of MFG porous plates with various boundary conditions in a fluid medium.The validity and reliability of the suggested method are confirmed by comparing numerical results of the present work with those from available works in the literature.The effects of different parameters on the thermal vibration response of MFG porous rectangular plates are studied in detail.These findings demonstrate that the behavior of the structure within a liquid medium differs significantly from that within a vacuum medium.Thereby,they offer appropriate operational approaches for the structure when employed in various mediums.展开更多
Combing with the generalized Hamiltonian system theory,by introducing a special form of sinusoidal function,a class of n-dimensional(n=1,2,3)controllable multi-scroll conservative chaos with complicated dynamics is co...Combing with the generalized Hamiltonian system theory,by introducing a special form of sinusoidal function,a class of n-dimensional(n=1,2,3)controllable multi-scroll conservative chaos with complicated dynamics is constructed.The dynamics characteristics including bifurcation behavior and coexistence of the system are analyzed in detail,the latter reveals abundant coexisting flows.Furthermore,the proposed system passes the NIST tests and has been implemented physically by FPGA.Compared to the multi-scroll dissipative chaos,the experimental portraits of the proposed system show better ergodicity,which have potential application value in secure communication and image encryption.展开更多
为研究颗粒阻尼器布置方案对多层结构减震性能的影响,制作了缩尺比为1/5的三层钢框架模型结构,进行了5条天然波下的地震模拟振动台试验,研究并联式单向单颗粒阻尼器(Parallel Single-dimensional Single Particle Damper,PSSPD)的减震...为研究颗粒阻尼器布置方案对多层结构减震性能的影响,制作了缩尺比为1/5的三层钢框架模型结构,进行了5条天然波下的地震模拟振动台试验,研究并联式单向单颗粒阻尼器(Parallel Single-dimensional Single Particle Damper,PSSPD)的减震控制效果。基于试验获得的模型自振频率、阻尼比等动力特性设计3种PSSPD布置方案,分析不同布置方案下模型结构的试验现象及位移和加速度响应。试验结果表明:PSSPD对结构响应峰值减震率可达到43.43%,均方根减震率可达到38.18%,其对多层结构具有良好的减震控制效果;PSSPD对结构均方根的平均减震效果要优于对峰值的平均减震效果;PSSPD布置方案对其减震效果影响显著,且其减震性能与本身参数、受控结构振动特性、地震动参数之间的耦合关系复杂。最后,建立PSSPD在任意布置方案下受控结构的力学模型,提出其数值分析流程。数值计算结果和试验结果在位移峰值及均方根方面具有良好的吻合度。展开更多
Magnetorheological (MR) dampers are one of the most promising new devices for civil infrastructural vibration control applications. However, due to their highly nonlinear dynamic behavior, it is very difficult to obta...Magnetorheological (MR) dampers are one of the most promising new devices for civil infrastructural vibration control applications. However, due to their highly nonlinear dynamic behavior, it is very difficult to obtain of a mathematical model of inverse MR damper that has an explicit relationship between the desired damper force and the command signal (voltage). This force voltage relationship is especially required for the structural vibration control design and simulation using MR dampers. This paper focuses on using a neural network (NN) technique to emulate the inverse MR damper model. The output of the neural network can be used to command the MR damper for generating desired forces. Numerical simulations are also presented to illustrate the effectiveness of this inverse model in semi active vibration control using MR dampers.展开更多
文摘An analytical method for analyzing the thermal vibration of multi-directional functionally graded porous rectangular plates in fluid media with novel porosity patterns is developed in this study.Mechanical properties of MFG porous plates change according to the length,width,and thickness directions for various materials and the porosity distribution which can be widely applied in many fields of engineering and defence technology.Especially,new porous rules that depend on spatial coordinates and grading indexes are proposed in the present work.Applying Hamilton's principle and the refined higher-order shear deformation plate theory,the governing equation of motion of an MFG porous rectangular plate in a fluid medium(the fluid-plate system)is obtained.The fluid velocity potential is derived from the boundary conditions of the fluid-plate system and is used to compute the extra mass.The GalerkinVlasov solution is used to solve and give natural frequencies of MFG porous plates with various boundary conditions in a fluid medium.The validity and reliability of the suggested method are confirmed by comparing numerical results of the present work with those from available works in the literature.The effects of different parameters on the thermal vibration response of MFG porous rectangular plates are studied in detail.These findings demonstrate that the behavior of the structure within a liquid medium differs significantly from that within a vacuum medium.Thereby,they offer appropriate operational approaches for the structure when employed in various mediums.
基金Project supported by the Natural Science Foundation of Tianjin,China(Grant No.18JCYBJC87700)the Natural Science Foundation of China(Grant No.61603274)。
文摘Combing with the generalized Hamiltonian system theory,by introducing a special form of sinusoidal function,a class of n-dimensional(n=1,2,3)controllable multi-scroll conservative chaos with complicated dynamics is constructed.The dynamics characteristics including bifurcation behavior and coexistence of the system are analyzed in detail,the latter reveals abundant coexisting flows.Furthermore,the proposed system passes the NIST tests and has been implemented physically by FPGA.Compared to the multi-scroll dissipative chaos,the experimental portraits of the proposed system show better ergodicity,which have potential application value in secure communication and image encryption.
文摘为研究颗粒阻尼器布置方案对多层结构减震性能的影响,制作了缩尺比为1/5的三层钢框架模型结构,进行了5条天然波下的地震模拟振动台试验,研究并联式单向单颗粒阻尼器(Parallel Single-dimensional Single Particle Damper,PSSPD)的减震控制效果。基于试验获得的模型自振频率、阻尼比等动力特性设计3种PSSPD布置方案,分析不同布置方案下模型结构的试验现象及位移和加速度响应。试验结果表明:PSSPD对结构响应峰值减震率可达到43.43%,均方根减震率可达到38.18%,其对多层结构具有良好的减震控制效果;PSSPD对结构均方根的平均减震效果要优于对峰值的平均减震效果;PSSPD布置方案对其减震效果影响显著,且其减震性能与本身参数、受控结构振动特性、地震动参数之间的耦合关系复杂。最后,建立PSSPD在任意布置方案下受控结构的力学模型,提出其数值分析流程。数值计算结果和试验结果在位移峰值及均方根方面具有良好的吻合度。
文摘Magnetorheological (MR) dampers are one of the most promising new devices for civil infrastructural vibration control applications. However, due to their highly nonlinear dynamic behavior, it is very difficult to obtain of a mathematical model of inverse MR damper that has an explicit relationship between the desired damper force and the command signal (voltage). This force voltage relationship is especially required for the structural vibration control design and simulation using MR dampers. This paper focuses on using a neural network (NN) technique to emulate the inverse MR damper model. The output of the neural network can be used to command the MR damper for generating desired forces. Numerical simulations are also presented to illustrate the effectiveness of this inverse model in semi active vibration control using MR dampers.
