Damage Detection Of Sandwich Panels With Truss Core Based On Structural Time Domain Response

In recent years,in the fields of aerospace and marine engineering,the application of complex space structures has become increasingly widespread.For large structures,once serious damage problems occur,structural performance degradation or failure will result,which will cause catastrophic accidents with very serious consequences.In the course of its service,if the damage of the structure and its development trend cannot be monitored in real time for a long time,it is difficult to find the real cause of the damage,and it is even more difficult to find and solve the hidden dangers of the structure in time.Therefore,the research and development of structural health monitoring technology to discover and eliminate structural safety hazards in a timely manner is of great significance to ensure the safe operation of structures.Due to its excellent comprehensive mechanical properties,the lattice structure has been widely used in many fields in recent years,but due to defects in the preparation process and loss in use,it often causes damage that cannot be recognized by the naked eye.With the gradual development of structural damage identification technology,domestic and foreign researchers have proposed a variety of damage identification methods,and verified them through theoretical analysis models and experiments.Aiming at the problem of damage identification of lattice sandwich plates,this paper proposes a time-domain response vibration damage identification method based on modal power,and the effectiveness of the method is verified by numerical simulation and vibration experiment.At the same time,the problem of damage identification of lattice sandwich panel damage under thermal environment is studied,and the influence of thermal environment on natural frequency and damage identification effect is also verified through numerical simulation and thermal experiment.In the damage identification method in this article,in order to suppress the fluctuations caused by boundary conditions and contact nodes,the Teager Energy Operator(TEO)method is used for processing;the wavelet transform method is used to process the data to improve the accuracy of damage identification.Aiming at the single damage and multiple damages of the lattice sandwich panel,this paper uses numerical simulation to verify the identification method.In the verification experiment,the Doppler laser vibrometer was used to obtain the time-domain displacement of the lattice sandwich plate,and then the damage identification method in this paper was used to compare the processing results to verify the reliability of the method.Due to the excessive parameters of the method,many factors may affect the effectiveness of the proposed method,including the excitation position,excitation frequency,sampling frequency,boundary conditions and the choice of wavelet.Therefore,the influence of the above factors on damage identification by this method is discussed in the numerical simulation.