The modeling method and identified method adapted to multi-degree-of-freedom structures with strucrural nonlinearities are established.The component mode synthesis method is used to establish the nonlinear governing e...The modeling method and identified method adapted to multi-degree-of-freedom structures with strucrural nonlinearities are established.The component mode synthesis method is used to establish the nonlinear governing equations by extending the connected relationships.Based on the modeling method,the Hilbert transform method is applied to identify the nonlinear stiffness of multi-degree-of-freedom structures.Nonlinear analysis and identification of a typical folding wing configuration with three freeplay hinges are investigated.The nonlinear governing equation is established based on present methods and the computing results of different stiffness are checked by finite element programming.In order to illustrate the influence of the nonlinearities,the frequency response characteristics of the structure are analyzed and Hilbert transform is performed.The Hilbert transform identification method is utilized to identify the nonlinear stiffness of nonlinear hinges in the time domain and several parametric studies are performed.In addition,the comparison of response is made to illustrate the feasibility of the methods.The results show that the extending component mode synthesis method in the present work can be used to establish the governing equation with structural nonlinearities.Based on the modeling method,the Hilbert transform identified method can be extended to multi-degree-of-freedom structures accurately.展开更多
Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. Th...Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a modelless structural input estimation are considered. The effectiveness of proposed methods has been carded out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.展开更多
基金国家自然科学基金项目(50579008)Support of the Foundation for Polish Science through TEAM Programme‘Smart&Safe+3 种基金co-financed by the EU European Regional Development Fundsupport of Structural Funds in the Operational Programme-Innovative Economy(IEOP)financed from the European Regional Development Fund-Projects No POIG.0101.02-00-013/08-00(MONIT)大连民族学院科研基金项目(20116207)大连民族学院自主科研基金项目(DC10040116)
基金supported by the National Natural Sciences Foundation of China(Grant Nos.91116005 and 10902006)
文摘The modeling method and identified method adapted to multi-degree-of-freedom structures with strucrural nonlinearities are established.The component mode synthesis method is used to establish the nonlinear governing equations by extending the connected relationships.Based on the modeling method,the Hilbert transform method is applied to identify the nonlinear stiffness of multi-degree-of-freedom structures.Nonlinear analysis and identification of a typical folding wing configuration with three freeplay hinges are investigated.The nonlinear governing equation is established based on present methods and the computing results of different stiffness are checked by finite element programming.In order to illustrate the influence of the nonlinearities,the frequency response characteristics of the structure are analyzed and Hilbert transform is performed.The Hilbert transform identification method is utilized to identify the nonlinear stiffness of nonlinear hinges in the time domain and several parametric studies are performed.In addition,the comparison of response is made to illustrate the feasibility of the methods.The results show that the extending component mode synthesis method in the present work can be used to establish the governing equation with structural nonlinearities.Based on the modeling method,the Hilbert transform identified method can be extended to multi-degree-of-freedom structures accurately.
文摘Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a modelless structural input estimation are considered. The effectiveness of proposed methods has been carded out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.
