The Dugdale model is applied to an orthotropic plate. Stresses along the crack line and displacements along the crack and elastic plastic interface were found. The effect of orthotropy on several isotropic properties was found to be a multiplicative factor which is a function of the state of orthotropy. The yield stress is assumed to follow a von Mises' yield criterion which was adopted to the orthotropic case. A limit on the severity of orthotropy for a given external load was found as well as a limit on the external load for a given state of orthotropy in order that the material would still follow the Dugdale hypothesis. Finally, as long as the material satisfies the above mentioned limits, the plastic zone size was shown to be unaffected by orthotropy. / Master of Science