Experimental characterisation of overstress accommodation in notched CFRP composite laminates

The understanding of notched specimen behaviour becomes necessary for the design of complex structures where different parts are mostly connected with bolts or rivets. The aim of this study is to characterise and quantify overstress accommodation which develops near the notch in three different composite laminates: the three have long carbon fibres as reinforcements, two have an epoxy matrix and the third one has a thermoplastic matrix. Tensile and compressive tests with several loadings/unloadings have been performed. To obtain whole-field displacement measurements, the white-light image-correlation technique has been used. To identify the damage localised around the hole, X-radiographs have also been performed. The comparison of the measured strain fields with the observed damage has demonstrated that the overstress accommodation is directly linked to the different types of damage occurring around the hole.