NANO-INDENTATION TESTING ON IN SITU MECHANICAL PROPERTIES OF ADHESIVES

摘要

The mechanical properties of adhesives are determined either from bulk material samples from adhesively bonded joints. For many years there has been controversy as to whether the mechanical properties obtained through testing bulk material are representative of the adhesive in its thin-film form. The use of adhesive bonding as a method of joining structural members in advanced structures is increasing. A major advantage of adhesive bonding is that it enables dissimilar materials to be joined and reduces the localized stresses encountered when using mechanical fastening such as bolts and rivets. In design process it is important to know unambiguously the mechanical properties of the materials being used. Because the adhesive is used in thin-film from, to obtain the mechanical characteristics of the adhesive in situ is hoped. In several papers it has been found that the adhesive material has different mechanical properties when tested in the thin-film form and bulk form, and further that a thickness effect exists, causing the properties to depend on the thickness of the bondline. However, the good agreement between thin-film and bulk properties is obtained in other papers. Moreover, the existence of the boundary layer in the adhesive layer is reported. In this paper, nano-indentation testing is carried out for the calibration specimens and two kinds of the specimens of adhesive. And the method in the former paper applied to know the distribution of local mechanical properties in the adhesive layers and the bulk material.