| Materials connected by different interface can be different from the original materials,since interface plays an important role in it. Bonding structure is widely used in aviation,aerospace, automotive and other fields, however, the existence of the bonding interfacedefects or inadequate bonding strength brings great hidden danger. As a kind of mechanicalwave, ultrasonic carries information of material structure when it spreads in it, therefore, theanalysis of ultrasonic signal can realize the detection and characterization of the bondingstructure.Glass glue, epoxy resin adhesive with different content of curing agent and hot pressingmethod were used to prepare polymer adhesive specimens. Bonding strength of differentbonding structures was measured and the section morphology were also analyzed. And thenultrasonic pulse echo method, transmission method and acousto-ultrasonic method were usedto detect the adhesive specimens; at last the received signal was analyzed.The results show that: all of the adhesive specimens have different bonding strength: thestrength of glass glue and epoxy resin adhesive without curing agent bonding specimen arethe lowest, the former interface adhesion strength is low, the latter interface cohesion strengthis low; the strength of epoxy resin adhesive with25%and50%curing agent bondingspecimens are higher, and the latter is higher than the former one; the strength of epoxy resinadhesive with75%curing agent bonding specimen is lower, because the specimen debonds;hot pressing specimen does not have interface, and the strength is the highest. Part of theparameters from different ultrasonic testing methods have a close relationship with thebonding strength: sound velocity of adhesive specimens calculated from the echo method canreflects bonding strength of different adhesive, sound velocity of interface layer can reflectsthe bonding strength of epoxy resin adhesive with different content of curing agent; there is agood corresponding relationship between transmission signal amplitude spectrum integrationand transmittance, power spectrum integration, normalized amplitude spectrum integrationand interface bonding strength; they can be used as the characteristic parameters of interfacebonding strength. Acousto-ultrasonic signal energy integration SWF, which reflects transmission efficiency of the stress wave in the adhesive specimens, has a goodcorresponding relationship with interface bonding strength, so it can be used as thecharacteristic parameter of interface bonding strength. Different ultrasonic testing methodshave different advantages and disadvantages; ultrasonic testing can be, on the whole, used asthe effective characterization of polymer interface bonding strength. |
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