Determination Of Stress Intensity Factors For The Shell Resting On Anonlinear Elastic Foundation

It is well known that initially curved sheets containing throughcracks have a reduced resistance to fracture initiation. Consequently, acrack in such structures can severely reduce their strength and can causesudden failure at a nominal tensile stress less than the material yieldstrength. Therefore, to ensure the integrity of a structure, the designer mustbe cognizant of the relation that exists among fracture load, crack shapeand size, material properties, and structural geometry. A relation of thiskind is called a fracture criterion and can be derived by the application ofthe fracture mechanics theory.The keystone for fracture analysis, is the determination of the stressfield distribution in the immediate vicinity of the crack tip. The generalsolution of such problem can be considered as the sum of solutions for twoauxiliary problems [30]. 1) The problem of an uncracked structuresubjected to given loads. The membrane and bending stresses will bedifferent from zero along the prospective crack site. 2) The problem of acracked structure with tractions specified on the crack surfaces. Thesetractions are equal and opposite to those found along the crack site inproblem 1. The solution for uncracked shell can be obtained, in Sections(2-3) and (2-4), without difficulty. Therefore, the present work isconcerned with the solution of problem 2 only, stress disturbanceproblem.