HOLOGRAPHIC EVALUATION OF EDGE DELAMINATION IN BARS BONDED TO A RIGIDSUPPORT WITH FOAM-ADHESIVE

When a bar having one end bonded to a rigid support with foam-adhesive is loaded, the high peeling stresses at the bonded edge foster edge d elamination along the interface of bonding. Upon inspection by double exposure holography, with an incremental point load applied at the fre e end of the bar between exposures, the indistinct fringe perturbation and the unknown resilience of the foam-adhesive (quantified by its fo undation modulus) impede unambiguous evaluation of the conditions of a dhesion. This paper describes a simple method fro rapid detection and assessment of artificially created edge delamination in such bar struc tures. The theoretical analysis elucidates the suitability of modellin g the bar as partially clamped, and having an equivalent slope at its support related to the foundation modulus. Two dimensionless parameter s are defined, which have between them a linear relationship for a non delaminated bonding but a nonlinear relationship for a delaminated one . Finally, a simple iterative procedure is described for estimating th e delaminated length without having to predetermine the elasticity of the support.