Strain and damage sensing by CNT modified adhesive films and fiber optic distributed sensing. Comparison of performances in a double lap bonded joint.

Bonded joints show a complex stress field, with large strain gradients, usually mainly known by numerical models. Experimental measurements are obtained at this paper, and   the feasibility and performances of two low intrusivity sensing techniques are compared.  The properties of CNT doped adhesive films are well known for uniform strain field; by plotting conductive patterns on the film, the response at high and low shear strain regions is also obtained, affording a much better insight on the possibilities of this technique.  An optical fibre embedded into the adhesive film, aligned to the loads, experience the strong strain gradients that are predicted by the models. Experimental results are compared to the numerical predictions given by Volkersen shear-lag model.