Yield Behaviour of a Structural Adhesive Under Complex Loading

摘要

Recent developments in bonded composite repair technology at the Aeronautical and Maritime Research Laboratory (AMRL) have been in the area of repairs to curved surfaces, eg. the proposed repairs to the F/A-18 aileron hinge and the F/A-18 bulkhead crotch region. Bonded composite repairs to curved surfaces induce through-thickness stresses as well as shear stresses in the adhesive. The yield behavior of AMRLs most common repair adhesive - FM73 - has not been investigated under such conditions of combined loading. In this report, a yield function for the repair adhesive FM73 is described, based upon the Modified Drucker-Prager/Cap Plasticity model. This yield function was selected based on experiments on a test specimen subjected to a range of combined stress states. A finite element (FE) analysis of test specimen (Iosipescu test specimen modified for adhesives) was carried out to establish its validity for obtaining data.