F. Lauro

Characterization of a structural adhesive by Digital Image Correlation

In the recent years, structural bonding takes an important place in assemblies techniques used for the automotive design. The next step to optimize the use of adhesive in car structures is to realize accurate finite element simulations of behaviour until failure of bonded joints. These kinds of calculations are only possible if fine behaviour and failure models are provided into the finite element software. In these works, tests on bulk adhesive specimens are realized to characterize the mechanical properties. 2D and 3D Digital Image Correlation are used to investigate the behaviour and failure of the shear and tensile specimens.

Elasto-viscoplasticity behaviour of a structural adhesive under compression loadings

Improvement of automotives’ crashworthiness is of high interest for governments prior to objectives focused on the reduction of passengers’ injuries. In these recent years, steel industries have studied the dynamic behaviour of tapered side rails so as to increase the capacities of energy absorption combined with light-weight aspects. On the basis of the global mass’ reduction of cars, bonded techniques have been tested with respect to the reduction of the mass/energy’s ratio. In this study, a test programme has been performed on a structural adhesive under a very large range of strain rates, thus [0.1;5000] /s. For that, a split Hopkinson bars device made of PA66 has been used so as to access to materials responses in the upper domain of strain rates, thus [500;5000] /s. To complete the expected domain of strain rates, compression tests have been done using a high-speed hydraulic machine on the same geometry from 0.1 up to 50 /s. A special mould has been machined and 2 sheets have prepared (thickness: 4 and 6 mm) in order to consider the effect of the pressure during the curing process. Water jet technique has been used to extract cylindrical samples from the sheet with accurate dimensions.