Secondary effects in the analysis of the post-buckling bending test

The post-buckling bending test can be used as an alternate to the classical three-point bending test for the mechanical characterisation of fibre-rein forced polymer composites. Its main interest is the avoidance of localised contact stress below the loading nose, which often induce the premature fai lure of the specimens under three-point bending conditions. The derivation of strength and modulus values from this test is based upon a mechanical an alysis, which is usually developed within the frame of the classical buckli ng analysis. This approach is based upon some assumptions, which have been justified in the real physical situation. The Validity of the beam approxim ation has especially been discussed for the usual specimen geometry. In add ition, the correcting factors due to membrane effects and the contribution of the rigid specimen grips are considered within the frame of the beam-ben ding problem. (C) 2000 Elsevier Science Ltd. All rights reserved.