Analysis Of Dynamic Characteristics Of Irregular Beam And Plate Structures

In the process of modern industrial development,the transformation and high-quality development of the manufacturing industry will inevitably lead to the industrial demand for new structural design and manufacturing,and new structural design is often more refined.With the introduction of various structural optimization design methods,more and more irregular configurations are introduced.For example,various airfoil structures widely used in aircraft wings and wind turbine blades are typical representatives.However,the current dynamic analysis research mainly focuses on the dynamic characteristics of the straight beam and rectangular plate,and the dynamic analysis of irregular plate is relatively limited.The cross-section area of irregular beam and plate is relatively small,and most of them adopt the design of the variable section and irregular boundary.Therefore,its dynamic characteristics will be more complex and diverse,and it is necessary to carry out targeted research.Because of the above practical problems,this paper takes irregular beam and plate structure as the research object and carries out the following studies:Based on the three-dimensional beam element of finite element theory,the dynamic analysis model of a variable section cantilever beam of a wind turbine blade was established,and the aerodynamic load model of wind turbine impeller was also established based on Blade Element Momentum theory.The steady-state deformation of the blade cantilever beam model under aerodynamic force was solved by the weak-coupling iterative method,and the calculation results were compared with the industrial software Bladed.On this basis,the steady-state deformation responses of the straight blade and swept blade were compared.The dynamic deformation responses of the straight blade and swept blade under gust wind load were solved by the Newmark-β method,and the load reduction performance of swept blade was verified.Based on the assumed modal method,a dynamic analysis model of a cantilever trapezoidal plate with additional concentrated mass was established,and the eigenvalue problem was solved.The feasibility and convergence of the assumed modal method in dynamic analysis of cantilever trapezoidal plate were verified by comparing with the results of finite element simulation and modal test.On this basis,the influence of the position and proportion of the additional mass on the natural frequency and mode shape of the cantilever trapezoidal plate is analyzed.Then a series of modal tests were carried out to verify the above conclusions.Because of the important significance of structural deformation monitoring for safe operation and getting a long operation life,a structural deformation monitoring method based on piezoelectric material and the artificial neural network is proposed in this thesis.Firstly,the coupling matrix equation of the cantilever beam with the piezoelectric ceramic plate attached was established based on the assumed modal method.The Newmark-β method was used to solve the forced vibration displacement response of the cantilever beam and the corresponding piezoelectric ceramic voltage response.Then the BP neural network model was established,and the results of the theoretical solution were used as the training and verification data set to monitor the dynamic deformation of the cantilever beam model.The detection effect of this method in the case with data noise is also analyzed.Finally,the feasibility of the monitoring method is verified by experiments.