Research On Damage Detection Method Of CFRP Structure Based On Ultrasonic Infrared Thermography

Carbon fiber reinforced polymer(CFRP)has many excellent properties that many metal materials do not possess.Its application scope has covered aerospace,wind power generation,pressure vessels,ocean engineering and other fields.CFRP will inevitably produce cracks and delamination damage during its manufacture and use,which will pose a great threat to the reliability and safety of the whole structure.Because CFRP are usually used in the key parts of structural engineering,therefore,it is of great significance to use non-destructive testing methods to detect the structural damage of CFRP.In this paper,the ultrasonic infrared thermography Non-destructive Testing is used to detect the damage of CFRP structure.Through the theoretical analysis,simulation and experimental verification,the distribution of temperature field at the damage site under ultrasonic excitation was analyzed to determine the existence of damage,the ultrasonic infrared thermography plays a certain role in the application of CFRP structural damage detection.The main research contents of this paper include four parts:1)The basic detection principles of the ultrasonic infrared thermography are introduced.Using the vibration dynamics theory,the collision vibrator model of the nonlinear contact collision between the horn and the plate is established to obtain the vibration equation,and the factors that affect the energy coupling are analyzed theoretically;Based on the theory of plane wave propagation,the propagation law of power ultrasonic in CFRP is derived;Theoretical analysis was made on the three sources of heat(Viscoelastic heating,Frictional heating,Plasticity-induced heat generation)in the damage area.2)In the ABAQUS finite element analysis software,a CFRP plate model containing crack damage was established,the commonly used surface source excitation and cylinder excitation method were optimized and improved.By changing the excitation amplitude and engagement force,the influence of the detection conditions on the characteristics of the damage heat generation is explained,and the mechanism of the detection conditions is also explored.3)A CFRP plate model with edge vertical crack and edge delamination is established to analyze the characteristics of the temperature field of the damage.By changing the thickness of the test piece,the direction of the crack,and the direction of the layer of the specimen,the influence of the damage on the heat generation of the damage was analyzed.The model of CFRP square tube and circular tube with crack damage is established,the influence of structure shape on the damage heat generation is analyzed from the angle of ultrasonic vibration,energy coupling and heat generation.4)The ultrasonic infrared thermography system platform was set up.Based on the simulation analysis,an ultrasonic infrared inspection test of CFRP structure damage was designed,and CFRP plate specimens with different crack lengths and different delamination areas were made,the thermal image processing algorithm is used to realize the quantitative identification of damage.At the same time,a CFRP square tube and a round tube specimen with impact damage were made to verify the damage detection effect under different excitation positions,and multiple damage detection tests were carried out to verify the effect of engagement force on the damage heat generation.Finally,the damage detection of CFRP truss structure and fan blade in practical engineering area was carried out.