On the effect of shear and local deformation in three-point bending tests

The three-point bending test is analysed taking into account shear and local deformation effects in the load application and supports. A new procedure is proposed in order to obtain flexural modulus, shear modulus and local deformation stiffness. Indentation tests and three-point bending tests at five different spans have been carried out on two specimens of T6T/F593 carbon/epoxy unidirectional composite. Since local deformation effects are not linear, slopes of load-deflection curves have been determined in three fixed strain ranges and a fixed load range. The best results have been obtained for the highest strain range, as local deformation effects can be considered linear. It has been seen that local deformation effects can have even more importance than shear effects in the case of small spans and large thickness.