Damage Detection Method And Experimental Study On Square Pyramid Space Grid Structure

With the development of economy and society,large span space structures were widely used in the past 50 years because of its light weight,reasonable structure,beautiful shape and good mechanical properties.However,due to the randomness of the load,the geometric characteristics of the structure and the change of the bearing capacity,the accident of structural failure has occurred occasionally.In order to ensure the safety of the structure,the large span grid structures began to do health monitoring and regular testing.The structural dynamic detection mainly included the selecting of the excitation point,the setting of the sensor placement,the structural damage detection method and the structural experiment.In this paper,based on the previous researches,the following work has been done:(1)The complete damage detection idea was produced including three aspects.Firstly,the selecting of the excitation point was based on Euclidean distance.Secondly,the sensors' arrangement method was based on the modified variance method.Thirdly,the damage identification method was based on wavelet transform and curvature modal difference.(2)Taking a 3 × 6 square-pyramid space girds structure as the research object,and through simulation,the above method is used to obtain the optimal excitation position and the sensors' arrangement.Based on the wavelet transform and curvature modal difference,y the damage locations can be determined.(3)A 3 × 6 square pyramid space girds structure was designed to do experiment.According to the results of numerical simulation,the excitation position and the position of the sensor were known.The INV3060 C instrument is used to collect the data and obtain the modal information of the structure.The results about frequency and modal shape between the numerical simulation and the experiment were similar,so the experimental results were effective.Given the damage location,according to the method of wavelet transform and curvature modal difference,the results show that the experimental results can determine the damage location accurately.The above detection theory can provide references for the damage detection of the space structures.