Simple Structural Damage Identification Method Based On Energy Density Research

With the continuous development of the aerospace industry and the missionrequirements increase, the reliability and service life of the aircraft ever-increasingdemands. Throughout the operational phase of the aircraft will be subjected to vibration,the impact of noise and other extreme environments and load, which may be caused byimpact damage, fatigue cracks, structural damage, thereby affecting the performance ofthe aircraft, and in severe catastrophic accident. Therefore, the aircraft structure damageidentification in orbit monitoring the health status of the aircraft structure, in order totake effective measures, has a very important engineering significance.Compared to traditional X-ray inspection, ultrasonic flaw detection and damageidentification method based on the vibration of the destructive testing method has theadvantages of online real-time damage diagnosis to get a lot of research. Most of thesestudies by the modal parameters and the dynamic response to the damage identification,suitable for large damage minor injury surveillance difficult. Energy-based structuraldamage identification method can overcome the shortcomings and deficiencies of theabove methods, to get more and more attention.In recent years, high-frequency wavetheory to the vibrational energy as the main variable energy finite element method instructural vibration noise analysis and control of the field of rapid development.Provides a new approach for structural damage identification.This paper reviewed the relevant literature, survey damage identification methodhas been carried out.In concluding the basis of the advantages and disadvantages ofthese methods, combined with the energy finite element method, structural damageidentification method based on the energy density distribution is given.This paper first according to the wave structure propagation in discontinuous node,will result in the reflection and transmission of energy, given typical aircraft structures(plate, beam), there are injuries in the wave equation; derived on this basis, given thedamagefinite element equation of local energy relations and damage the structure ofenergy; to solve the analysis of the damage the structure of the energy densitydistribution, by the method of simulation to verify the correctness and validity.Then, the combination of crack is the most common form of structural damage,thisidentification method in the crack beam, according to the two-step method in the fieldof damage identification, combined with the bending spring model and the wavecharacteristics of the damaged beams to derive a single crackthe frequency equation ofthe two-crack cantilever; example by the finite element simulation of the cantilevermodelunder various conditions, various conditions beam Crack position identificationbased on the energy density, the frequency combination of cracked beam equation to calculate the crack depth.Finally, based on the results of theoretical studies, this paper designed a pilot,experimental verification of the cantilever structure. Available through experiments: Inthis paper, energy density-based structural damage detection method is effective andreliable in dealing with structural damage identification problems.Studies have shown that the structure damage identification method described inthis article applies to medium and high frequency, and sensitive to small defects of thestructure, at the same time with online real-time, easy operation, high accuracy, withoutthe complexity of data processing, etc., with a higher value in engineering.Plate beamstructure is an important part of the complex aircraft, the research results of therepresentation and promotion, this study can provide guidance for the future of complexaircraft structure damage identification and on-line real-time health monitoring.