An experimental method dedicated to the dynamic characterization of structural adhesives under drop weight conditions

Adhesive bonding is a commonly used method in multi-materials assemblies dedicated to the transport fields. In order to ensure structures integrity and users safety, the knowledge of the mechanical behaviour of structural adhesives used in these assemblies under impact conditions appears to be an essential prerequisite. To date, numerous tests combining usual specimens geometry e.g. single lap joint, butt joint, etc. and high velocity testing rigs exist and are used. Among these, most allow comparative studies and a few provide a partial identification of the material properties of the investigated adhesive. In this study, an experimental method dedicated to the dynamic characterization of structural adhesives under drop weight condition is proposed. On the basis of existing works, a modified Arcan specimen and a dynamic tensile testing mean were developed and are presented. The Arcan geometry allows to test the adhesive under various loading directions and so to obtain its mechanical response envelope. Design strategies are also implemented in order to obtain time stable and quasi-homogeneous stress distributions in the adhesive during the tests. At last, the dynamic characterization of a Dow ® Betamate TM 1496V adhesive is proposed. Results are repeatable and show a strain rate dependent behaviour validating the appropriateness of the experimental approach.