DETERMINATION OF STRESS GRADIENTS IN FIBROUS COMPOSITES BY X-RAY-DIFFRACTION FROM FILLERS

The method of X-ray diffraction from crystalline filler particles has been applied to fibrous composites. The stress/strain transfer behavio ur between the particles and the surrounding matrix is described by th e X-ray elasticity constants (XEC). These constants have been determin ed by experiment as well as by means of theoretical models. Above all for the first time, complete quantitative XEC are given for CdO filler s which have turned out to be the most suitable filler material. The e xact knowledge of the XEC of particle/laminate systems formed the foun dation to apply the method to analyse interlaminar stress concentratio ns. For the first time, stress gradient measurements even on notched l aminates have been successfully carried out. Free edge stress distribu tions obtained by experiments are in good agreement with results from finite element simulations.