Damage Identification Of Lattice Structures Based On High Frequency Dynamic Responses

Lattice sandwich structure is composed of two thin plates with high porosity.As a new type of material,lattice sandwich structure has excellent mechanical properties due to its complex design,multi-functional grid has been widely used in the field of aerospace.In the preparation of sandwich structure or single cell defects,due to the complexity of its structure,it appears damage in the process of use.The structural stiffness will decrease rapidly and cause serious accidents.Therefore,the key to solve this problem is to detect the damage caused by sandwich grid structure timely and accurately.Aiming at the debonding damage of light sandwich structure,a damage detection method of high frequency dynamic response is proposed.In this document,along with numerical simulation,modal frequency of the local damage is obtained by numerical simulation.The resonance response characteristics of the locally defect structure are measured at a natural frequency,which is the central frequency and frequency range.In this research,the frequency response function method is used to obtain multiple modal shapes in the wide frequency band;the ODS(operational deformation shapes)test method is used to obtain the structural response under multiple specific frequency excitation;the sound field excitation is used to obtain the structural broadband vibration sound pressure level response.The response data obtained by these three methods are analyzed respectively.Then,using the damage index proposed in this paper,the damage imaging is realized.Setting up two different experimental platforms,PZT and non-contact loudspeakers have been established in this document,based on a thorough analysis of defect detection.SLDV is used to identify the affected area and the layer of one-sided damage,and analysis of defect vibration signal,then the damage location was determined.The imaging method proposed in this paper no need no information is required of the structure,especially non-contact damage detection.It only needs to measure the vibration response of the structure in a wide frequency band.Combined with the proposed damage imaging method,the damage location can be achieved.The fact also proves that the damage detection method is applicable.