INTRODUCTION
In the design of stressed-skin structure, consideration must sometimes be given to the critical stresses for a sheet under a combination of shear and direct stress, The upper surface of a wing in flight, for example, may be subjected to combined shear and compressive stress and the lower surface to combined shear and tensile stress simultaneously. Under this condition the upper surface may buckle at a lower compressive stress than if the shear were. not present and the critical shear stress for the lower surface will he increased by the present of the tensile stress. The purpose of the present report is to specify the combination of shear and direst stress under which such. surfaces may be expected to buckle.