Experimental determination of stress concentrations in orthotropic composites

Determining stress raisers necessitates accurate knowledge of the stresses on the edge of the geometric discontinuity. Recognizing difficulties in obt aining measured stresses at the edge of a hole or notch, the least-squares method in conjunction with a Laurent series representation of the stress fu nctions and local collocation, is used to evaluate reliable stresses on the boundary of holes in loaded composites from measured data away from the ho le. Advantages over previous such hybrid analyses include the fact that few measured input data are required that they can be arbitrarily located and that only a very few terms are needed in the stress function representation . The approach is illustrated fur stress input as well as moire-measured di splacements. Application to each of the three classes of orthotropy is deli berately addressed.