Modal Analysis Of Lamella Single Layer Reticulated Shells Based On Digital Image Detection Technology

Due to the characteristics of large span and rich and beautiful shape,the cross-space structure has gradually been accepted as a landmark building in major cities.Therefore,it is extremely important to monitor the structure during the construction and operation stages in order to ensure the safety performance of large structures.Damage diagnosis based on structural vibration is the mainstream method of structural diagnosis.The core of structural safety assessment is to obtain corresponding dynamic characteristics through modal analysis of structures.At present,most vibration test data acquisition are based on acceleration sensors.In order to measure the complete data,a large number of sensors or multiple tests are required.The on-site operation is cumbersome and the workload is large.In this paper,the vibration measurement method based on digital image detection technology is introduced.The number of measurement points is large and can be selected arbitrarily,and the field operation is simple.It is a new kind of non-contact and high precision measurement method.In this paper,the author mainly aims at the lamella single Layer reticulated shells structure model and the application of digital image processing technology to the dynamic displacement measurement of the nodes of the structure.In order to verify the feasibility and reliability of the proposed method,the traditional detection method,finite element calculation and digital image processing technique are used to study the dynamic characteristics of the static load test.And...The main research contents and research results of this paper are as follows:(1)The background and significance of this research are introduced by reviewing the relevant literature,the structure detection technology and digital image processing technology are summarized according to the current research situation at home and abroad,and the modal analysis of the applied modal analysis is introduced based on the dynamic characteristics of this paper.(2)In the laboratory environment,the sensitivity analysis and correction of the finite element model are carried out through the static loading test results,and the accuracy of static displacement measurement of the nodes in the structural surface based on the digital edge image method is proved to be reliable,and the horizontal direction position can only be recognized at a time.The limitations of one edge.It lays the foundation for the vibration test in the surface of a single layer mesh shell model.(3)By means of digital image detection,the Dynamic characteristics of single layer mesh shell are analyzed,and the frequency and corresponding vibration patterns are obtained.This provides a new idea for the study of dynamic characteristics of large span space.(4)Through experimental operations,the process of digital image detection is described in detail,and the results of finite element method,traditional method,and digital image method are compared and analyzed.It is concluded that digital image detection has a more accurate effect on low-order frequencies,and the error increases with the increase of order.However,the error is within 4 % to meet the requirements of engineering application accuracy.(5)The vibration displacement signals of the nodes in the single layer mesh face are collected by different angles.The time synchronization problem is solved by the audio peak to realize the joint splicing in the surface.